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This paper aims to present comprehensive lists of accurate natural frequencies of isotropic thin free rectangular plates constrained only by translational springs distributed uniformly on the edges. Analytical and numerical approaches are employed to study the free vibration of the plates. The first approach is an extension of Ritz method, and second approach is the finite element method coded by the author. Numerical examples cover rectangular plates from totally free plate to totally simply supported on all edges. Convergence and comparison studies are made to establish accuracy of these solutions. Nine numerical examples are presented in terms of different of elastic constraints, and the lowest six frequency parameters are provided in the examples with different aspect ratios.

This paper aims to present comprehensive lists of accurate natural frequencies of isotropic thin free rectangular plates constrained only by translational springs distributed uniformly on the edges. Analytical and numerical approaches are employed to study the free vibration of the plates. The first approach is an extension of Ritz method, and second approach is the finite element method coded by the author. Numerical examples cover rectangular plates from totally free plate to totally simply supported on all edges. Convergence and comparison studies are made to establish accuracy of these solutions. Nine numerical examples are presented in terms of different of elastic constraints, and the lowest six frequency parameters are provided in the examples with different aspect ratios.

Dynamic load analysis of Ultra-High-Performance Concrete (UHPC) beams is crucial, given the material's widespread use in bridges, enabling engineering feats like 100 meter single-span bridges. Structural vibration monitoring aids in evaluating a structure's ability to withstand dynamic loads, employing finite element (FE) model analysis for verification and enhancement. This study utilizes ANSYS for finite element modelling (FEM) and modal analysis, assessing the UHPC beam's structural integrity. An undamaged UHPC beam model validates dynamic properties, reducing disparities between analytical and experimental results. Modal properties of the first cracked and damaged UHPC beam are updated to represent actual conditions. Vibration analysis reveals inherent vibration modes, frequencies, and forms. Structural stiffness analysis verifies the relationship between stiffness and dynamic qualities. Experimental data updates the UHPC beam model, establishing a connection between structural stiffness and natural frequency under various conditions. In conclusion, ANSYS was employed for FEM, modal analysis, and parameterization verification, revealing the importance of accurate UHPC feature identification and meshing size. Discrepancies highlight the need for experimental tests, reducing differences between FEM and empirical findings. The numerical analysis in ANSYS underscores the correlation between structural stiffness and natural frequency, enabling precise structural health monitoring for UHPC beam damage or deterioration identification.

Accurate determination of modal parameters for disk-like structures submerged in heavy fluids is a topic of interest in many fields. For instance, some type of hydraulic turbomachinery can be modelled as disk structures due to the similarity in their mode shapes. Although in the recent years many studies have analyzed and correctly predicted the fluid added mass effect on the natural frequencies and mode shapes of these types of structures, it is particularly challenging to determine fluid damping and characterize its most influential effects. In this article, the influence of vibration amplitude on the fluid damping ratio of a submerged disk, when the disk gets close to a rigid wall, is analytically and experimentally studied. Particularly, the first diametrical modes of the disk have been analyzed at different vibration amplitudes and at very small distances away from a rigid surface. The disk is put in a resonant state by means of a piezoelectric patch generating a harmonic excitation and the response is measured by means of a Laser Doppler Vibrometer (LDV). The damping ratio is obtained directly from the vibrating free decay following a sudden stop of the excitation. It is shown that the fluid damping ratio values are related to the vibration amplitude: there is a trend of increasing damping ratio as the amplitude of the vibration increases. This effect is found to be much larger for small distances between the disk and the rigid surface., Peer Reviewed, Postprint (published version)

A mode shape is a specific pattern of vibration executed by a mechanical system at a specific frequency. Different mode shapes will be associated with different frequencies. The experimental technique of modal analysis discovers these mode shapes and the frequencies. In this paper modal analysis has been carried out to determine the mode shapes and the respective frequencies of perforated plates with regard to change in the dimension of the perforations and the distance between the perforations (pitch).

Earthquake engineers have taken many precautions in their building designs to protect and minimize destructive effects. In this way, many new design and reinforcement methods have been developed against seismic loads. The use of a tuned mass damper (TMD) is one of the developed methods. One of the most important negative aspects of the use of TMD is the increase in the structural period. Therefore, in this study, the effects of TMD on periods and mode shapes in simeterically reinforced concrete building model were investigated. For this, two models with and without TMD were created by the finite element method and modal parameters were compared. As a result of the data obtained, it has been observed that the building model makes more balanced displacements, as can be understood from the mode shapes, without increasing the period of the building to a dangerous level. It is known that TMD reduces the seismic effect by acting in the opposite direction to the seismic effect on the structure. Tuned mass damper can be used in structures, provided that it does not increase the structure period too much.

Earthquake engineers have taken many precautions in their building designs to protect and minimize destructive effects. In this way, many new design and reinforcement methods have been developed against seismic loads. The use of an active mass damper (AMD) is one of the developed methods. One of the most important negative aspects of the use of AMD is the increase in the structural period. Therefore, in this study, the effects of AMD on periods and mode shapes in symmetrically reinforced concrete building model were investigated. For this, two models with and without AMD were created by the finite element method and modal parameters were compared. As a result of the data obtained, it has been observed that the RC building model makes more balanced displacements, as can be understood from the mode shapes, without increasing the period of the RC building to a dangerous level. It is known that AMD reduces the seismic effect by acting in the opposite direction to the seismic effect on the structure. Active mass damper can be used in reinforced concrete buildings, provided that it does not increase period too much.

Earthquake engineers have taken many precautions in their building designs to protect and minimize destructive effects. In this way, many new design and reinforcement methods have been developed against seismic loads. The use of a tuned mass damper (TMD) is one of the developed methods. One of the most important negative aspects of the use of TMD is the increase in the structural period. Therefore, in this study, the effects of TMD on periods and mode shapes in simeterically reinforced concrete building model were investigated. For this, two models with and without TMD were created by the finite element method and modal parameters were compared. As a result of the data obtained, it has been observed that the building model makes more balanced displacements, as can be understood from the mode shapes, without increasing the period of the building to a dangerous level. It is known that TMD reduces the seismic effect by acting in the opposite direction to the seismic effect on the structure. Tuned mass damper can be used in structures, provided that it does not increase the structure period too much.

Earthquake engineers have taken many precautions in their building designs to protect and minimize destructive effects. In this way, many new design and reinforcement methods have been developed against seismic loads. The use of a pendulum tuned mass damper (PTMD) is one of the developed methods. One of the most important negative aspects of the use of PTMD is the increase in the structural period. Therefore, in this study, the effects of PTMD on periods and mode shapes in symmetrically reinforced concrete water tank model were investigated. For this, two models with and without PTMD were created by the finite element method and modal parameters were compared. As a result of the data obtained, it has been observed that the water tank model makes more balanced displacements, as can be understood from the mode shapes, without increasing the period of the water tank to a dangerous level. It is known that PTMD reduces the seismic effect by acting in the opposite direction to the seismic effect on the structure. Pendulum tuned mass damper can be used in reinforced concrete water tanks, provided that it does not increase period too much.

Use of Sandwich construction for an aircraft structural component is very common to the present day. One of the primary requirements of aerospace structural materials is that they should have low density, very stiff and strong. Sandwich panels are thin-walled structures fabricated from two flat sheets separated by a low density core. We have investigated here is of aluminium honeycomb structure because of excellent crush strength and fatigue resistance. Sandwich panels have a very high stiffness to weight ratio with respect equivalent solid plate because of low density core. FEA modeling is developed by consideration of rotary inertia. The free vibration analysis of sandwich panels is studied. Four noded isoparametric shell element is used for FEA. The effects of sandwich design parameters, such as face thickness, core thickness and pitch, on the global bending and vibration responses are determined. Convergence study is also included for high accuracy of the results. Analytical results are based on classical bending theory. Mode shapes and corresponding natural frequencies are studied for simply supported sandwich panel and cantilever condition.

Use of Sandwich construction for an aircraft structural component is very common to the present day. One of the primary requirements of aerospace structural materials is that they should have low density, very stiff and strong. Sandwich panels are thin-walled structures fabricated from two flat sheets separated by a low density core. We have investigated here is of aluminium honeycomb structure because of excellent crush strength and fatigue resistance. Sandwich panels have a very high stiffness to weight ratio with respect equivalent solid plate because of low density core. FEA modeling is developed by consideration of rotary inertia. The free vibration analysis of sandwich panels is studied. Four noded isoparametric shell element is used for FEA. The effects of sandwich design parameters, such as face thickness, core thickness and pitch, on the global bending and vibration responses are determined. Convergence study is also included for high accuracy of the results. Analytical results are based on classical bending theory. Mode shapes and corresponding natural frequencies are studied for simply supported sandwich panel and cantilever condition.

Use of Sandwich construction for an aircraft structural component is very common to the present day. One of the primary requirements of aerospace structural materials is that they should have low density, very stiff and strong. Sandwich panels are thin-walled structures fabricated from two flat sheets separated by a low density core. We have investigated here is of aluminium honeycomb structure because of excellent crush strength and fatigue resistance. Sandwich panels have a very high stiffness to weight ratio with respect equivalent solid plate because of low density core. FEA modeling is developed by consideration of rotary inertia. The free vibration analysis of sandwich panels is studied. Four noded isoparametric shell element is used for FEA. The effects of sandwich design parameters, such as face thickness, core thickness and pitch, on the global bending and vibration responses are determined. Convergence study is also included for high accuracy of the results. Analytical results are based on classical bending theory. Mode shapes and corresponding natural frequencies are studied for simply supported sandwich panel and cantilever condition.

Use of Sandwich construction for an aircraft structural component is very common to the present day. One of the primary requirements of aerospace structural materials is that they should have low density, very stiff and strong. Sandwich panels are thin-walled structures fabricated from two flat sheets separated by a low density core. We have investigated here is of aluminium honeycomb structure because of excellent crush strength and fatigue resistance. Sandwich panels have a very high stiffness to weight ratio with respect equivalent solid plate because of low density core. FEA modeling is developed by consideration of rotary inertia. The free vibration analysis of sandwich panels is studied. Four noded isoparametric shell element is used for FEA. The effects of sandwich design parameters, such as face thickness, core thickness and pitch, on the global bending and vibration responses are determined. Convergence study is also included for high accuracy of the results. Analytical results are based on classical bending theory. Mode shapes and corresponding natural frequencies are studied for simply supported sandwich panel and cantilever condition.

Use of Sandwich construction for an aircraft structural component is very common to the present day. One of the primary requirements of aerospace structural materials is that they should have low density, very stiff and strong. Sandwich panels are thin-walled structures fabricated from two flat sheets separated by a low density core. We have investigated here is of aluminium honeycomb structure because of excellent crush strength and fatigue resistance. Sandwich panels have a very high stiffness to weight ratio with respect equivalent solid plate because of low density core. FEA modeling is developed by consideration of rotary inertia. The free vibration analysis of sandwich panels is studied. Four noded isoparametric shell element is used for FEA. The effects of sandwich design parameters, such as face thickness, core thickness and pitch, on the global bending and vibration responses are determined. Convergence study is also included for high accuracy of the results. Analytical results are based on classical bending theory. Mode shapes and corresponding natural frequencies are studied for simply supported sandwich panel and cantilever condition.

Use of Sandwich construction for an aircraft structural component is very common to the present day. One of the primary requirements of aerospace structural materials is that they should have low density, very stiff and strong. Sandwich panels are thin-walled structures fabricated from two flat sheets separated by a low density core. We have investigated here is of aluminium honeycomb structure because of excellent crush strength and fatigue resistance. Sandwich panels have a very high stiffness to weight ratio with respect equivalent solid plate because of low density core. FEA modeling is developed by consideration of rotary inertia. The free vibration analysis of sandwich panels is studied. Four noded isoparametric shell element is used for FEA. The effects of sandwich design parameters, such as face thickness, core thickness and pitch, on the global bending and vibration responses are determined. Convergence study is also included for high accuracy of the results. Analytical results are based on classical bending theory. Mode shapes and corresponding natural frequencies are studied for simply supported sandwich panel and cantilever condition.

In most experimental investigations, the accelerometer mass effect is neglected since the accelerometer mass is small in comparison to the mass of the test construction. When a lightweight construction is examined, however, this impact is noticeable. The goal of this research is to see how mass affects thin plate vibration. The characteristics of interest were the natural frequency and its associated mode shape. Using finite element analysis, the thin plate simply supported boundary condition was studied. The mass was added to the plate and distinct sites were chosen for mounting. The mass has a considerable influence on certain of the structure's modes, while it has no effect on others, according to the findings. The mass, which was placed at the plate's highest deflection point, revealed significant variations in natural frequencies and their associated mode shapes. For the mass mounted at the nodal line of the specific mode, there are no notable changes in natural frequency or mode shapes. The influence of mass is found to be dependent on the position of the mass, the vibration mode, and the magnitude of the mass. &nbsp

A mode shape is a specific pattern of vibration executed by a mechanical system at a specific frequency. Different mode shapes will be associated with different frequencies. The experimental technique of modal analysis discovers these mode shapes and the frequencies. In this paper modal analysis has been carried out to determine the mode shapes and the respective frequencies of perforated plates with regard to change in the dimension of the perforations and the distance between the perforations (pitch).

In most experimental investigations, the accelerometer mass effect is neglected since the accelerometer mass is small in comparison to the mass of the test construction. When a lightweight construction is examined, however, this impact is noticeable. The goal of this research is to see how mass affects thin plate vibration. The characteristics of interest were the natural frequency and its associated mode shape. Using finite element analysis, the thin plate simply supported boundary condition was studied. The mass was added to the plate and distinct sites were chosen for mounting. The mass has a considerable influence on certain of the structure's modes, while it has no effect on others, according to the findings. The mass, which was placed at the plate's highest deflection point, revealed significant variations in natural frequencies and their associated mode shapes. For the mass mounted at the nodal line of the specific mode, there are no notable changes in natural frequency or mode shapes. The influence of mass is found to be dependent on the position of the mass, the vibration mode, and the magnitude of the mass. &nbsp

Dagens planering och projektering av konstruktioner präglas av ett resursutnyttjande, miljömässigt och ekonomiskt tänk, där resultatet kan medföra brister med avseende på dynamiken. Därmed är det ytterst viktigt att skapa goda förutsättningar för noggranna beräkningsmodeller som i ett projekteringsskede kan representera konstruktionernas dynamiska beteende. I denna rapport utfördes en jämförelseanalys mellan en FE-modell och en fältmätning, där Folke Bernadottes bro har använts som underlag. Syftet är att presentera skillnader och likheter i naturliga frekvenser och modformer baserat på jämförelseanalysen, samt belysa några av de viktigaste faktorerna bakom dessa. Resultatet visade för en kalibrerad FE-modell 11 % genomsnittlig skillnad för de naturliga frekvenserna och 99 % överensstämmelse med avseende på modformerna, där den mest väsentliga parametern i modellen var upplagsvillkoren., Today's planning and design of constructions is characterized by a resource utilization, environmental and economic thinking, where the result can lead to shortcomings with regard to dynamic behaviour. Thus, it is extremely important to create good conditions for accurate calculation models that in a design phase can represent the dynamic behaviour of the structures. In this report, a comparison analysis was performed between an FE-model and a field measurement, where Folke Bernadotte's bridge has been used as basis. The purpose is to present differences and similarities in natural frequencies and mode shapes based on the comparative analysis, and to highlight some of the most important factors behind these. The result showed for a calibrated FE-model an average difference of 11 % for the natural frequencies and 99 % agreement with respect to the mode shapes, where the most important parameter in the model was the support conditions.

Earthquake engineers have taken many precautions in their building designs to protect and minimize destructive effects. In this way, many new design and reinforcement methods have been developed against seismic loads. The use of an active mass damper (AMD) is one of the developed methods. One of the most important negative aspects of the use of AMD is the increase in the structural period. Therefore, in this study, the effects of AMD on periods and mode shapes in symmetrically reinforced concrete building model were investigated. For this, two models with and without AMD were created by the finite element method and modal parameters were compared. As a result of the data obtained, it has been observed that the RC building model makes more balanced displacements, as can be understood from the mode shapes, without increasing the period of the RC building to a dangerous level. It is known that AMD reduces the seismic effect by acting in the opposite direction to the seismic effect on the structure. Active mass damper can be used in reinforced concrete buildings, provided that it does not increase period too much.

Earthquake engineers have taken many precautions in their building designs to protect and minimize destructive effects. In this way, many new design and reinforcement methods have been developed against seismic loads. The use of a tuned mass damper (TMD) is one of the developed methods. One of the most important negative aspects of the use of TMD is the increase in the structural period. Therefore, in this study, the effects of TMD on periods and mode shapes in simeterically reinforced concrete building model were investigated. For this, two models with and without TMD were created by the finite element method and modal parameters were compared. As a result of the data obtained, it has been observed that the building model makes more balanced displacements, as can be understood from the mode shapes, without increasing the period of the building to a dangerous level. It is known that TMD reduces the seismic effect by acting in the opposite direction to the seismic effect on the structure. Tuned mass damper can be used in structures, provided that it does not increase the structure period too much.

Earthquake engineers have taken many precautions in their building designs to protect and minimize destructive effects. In this way, many new design and reinforcement methods have been developed against seismic loads. The use of a pendulum tuned mass damper (PTMD) is one of the developed methods. One of the most important negative aspects of the use of PTMD is the increase in the structural period. Therefore, in this study, the effects of PTMD on periods and mode shapes in symmetrically reinforced concrete water tank model were investigated. For this, two models with and without PTMD were created by the finite element method and modal parameters were compared. As a result of the data obtained, it has been observed that the water tank model makes more balanced displacements, as can be understood from the mode shapes, without increasing the period of the water tank to a dangerous level. It is known that PTMD reduces the seismic effect by acting in the opposite direction to the seismic effect on the structure. Pendulum tuned mass damper can be used in reinforced concrete water tanks, provided that it does not increase period too much.

Use of Sandwich construction for an aircraft structural component is very common to the present day. One of the primary requirements of aerospace structural materials is that they should have low density, very stiff and strong. Sandwich panels are thin-walled structures fabricated from two flat sheets separated by a low density core. We have investigated here is of aluminium honeycomb structure because of excellent crush strength and fatigue resistance. Sandwich panels have a very high stiffness to weight ratio with respect equivalent solid plate because of low density core. FEA modeling is developed by consideration of rotary inertia. The free vibration analysis of sandwich panels is studied. Four noded isoparametric shell element is used for FEA. The effects of sandwich design parameters, such as face thickness, core thickness and pitch, on the global bending and vibration responses are determined. Convergence study is also included for high accuracy of the results. Analytical results are based on classical bending theory. Mode shapes and corresponding natural frequencies are studied for simply supported sandwich panel and cantilever condition.

A mode shape is a specific pattern of vibration executed by a mechanical system at a specific frequency. Different mode shapes will be associated with different frequencies. The experimental technique of modal analysis discovers these mode shapes and the frequencies. In this paper modal analysis has been carried out to determine the mode shapes and the respective frequencies of perforated plates with regard to change in the dimension of the perforations and the distance between the perforations (pitch).

In most experimental investigations, the accelerometer mass effect is neglected since the accelerometer mass is small in comparison to the mass of the test construction. When a lightweight construction is examined, however, this impact is noticeable. The goal of this research is to see how mass affects thin plate vibration. The characteristics of interest were the natural frequency and its associated mode shape. Using finite element analysis, the thin plate simply supported boundary condition was studied. The mass was added to the plate and distinct sites were chosen for mounting. The mass has a considerable influence on certain of the structure's modes, while it has no effect on others, according to the findings. The mass, which was placed at the plate's highest deflection point, revealed significant variations in natural frequencies and their associated mode shapes. For the mass mounted at the nodal line of the specific mode, there are no notable changes in natural frequency or mode shapes. The influence of mass is found to be dependent on the position of the mass, the vibration mode, and the magnitude of the mass. &nbsp

Timber is a building material that is becoming more common and of interest for use in high-rise buildings. One of the reasons is that timber requires less energy input for the manufacturing process of the material compared to non-wood based materials. When designing high- rise timber buildings it is of great significance to understand the dynamic behavior of the structure. One method to obtain the dynamic properties is to use Operational Modal Analysis, which is based on the structural response from operational use. Finite element (FE) analysis is a tool which can be used for dynamic analysis for large structures. In this study an Operation Modal Analysis (OMA) was conducted on a four-story timber building in Växjö. A finite element model was created of the same building using commercial FE packages. Based on the mode shapes and natural frequencies obtained from the OMA, the FE model was fine-tuned. The purpose of this thesis is to gain knowledge of which parameters that might have a significant role in finite element modelling for a structural dynamic analysis. The aim is to develop a finite element model that accurately simulates the dynamic behavior of the tested building. It was shown from the result that is possible with an enough detailed FE model to capture the dynamic behaviour of a structure. The parameters that had the largest effect on the result can be pointed to the mass and the stiffness of the structure., Trä är ett byggnadsmaterial som börjar bli allt mer vanligt och är av intresse att använda som stommaterial för höga byggnader. En anledning till detta är att det krävs mindre energi i tillverkningsfasen för trä jämfört med stål och betong. Vid dimensionering av höga träbyggnader är det essentiellt att förstå byggnadens dynamiska egenskaper. För att ta fram en byggnads dynamiska egenskaper kan en metod som benämns Operational Modal Analysis (OMA) tillämpas vilken baseras på byggnadens rörelser vid daglig användning. Finita element (FE) metoden är ett verktyg som kan användas vid dynamisk analys för större byggnader. I detta arbete genomfördes en OMA för ett fyravåningshus med trästomme beläget i Växjö. Genom användning av kommersiella FE-mjukvaror togs en finita element modell av samma byggnad fram. Baserat på de egenfrekvenser och egenmoder erhållna från OMA, uppdaterades FE-modellen därefter. Syftet med detta arbete är att erhålla kunskap kring vilka parametrar som har betydelse vid FE-modellering med hänsyn till dynamisk analys. Syftet är även att validera den prototyp av datainsamlingsenhet som använts vid fältmätningen. Målet med arbetet är att ta fram en FE-modell som på ett korrekt sätt beskriver den testade byggnadens dynamiska beteende. Resultatet av arbetet påvisar att med en tillräckligt detaljerad FE-modell är det möjligt att erhålla en byggnads dynamiska egenskaper. De parametrar som har störst inverkan på resultatet är byggnadens styvhet och inkluderad massa.

A mode shape is a specific pattern of vibration executed by a mechanical system at a specific frequency. Different mode shapes will be associated with different frequencies. The experimental technique of modal analysis discovers these mode shapes and the frequencies. In this paper modal analysis has been carried out to determine the mode shapes and the respective frequencies of perforated plates with regard to change in the dimension of the perforations and the distance between the perforations (pitch).

In most experimental investigations, the accelerometer mass effect is neglected since the accelerometer mass is small in comparison to the mass of the test construction. When a lightweight construction is examined, however, this impact is noticeable. The goal of this research is to see how mass affects thin plate vibration. The characteristics of interest were the natural frequency and its associated mode shape. Using finite element analysis, the thin plate simply supported boundary condition was studied. The mass was added to the plate and distinct sites were chosen for mounting. The mass has a considerable influence on certain of the structure's modes, while it has no effect on others, according to the findings. The mass, which was placed at the plate's highest deflection point, revealed significant variations in natural frequencies and their associated mode shapes. For the mass mounted at the nodal line of the specific mode, there are no notable changes in natural frequency or mode shapes. The influence of mass is found to be dependent on the position of the mass, the vibration mode, and the magnitude of the mass. &nbsp

Dagens planering och projektering av konstruktioner präglas av ett resursutnyttjande, miljömässigt och ekonomiskt tänk, där resultatet kan medföra brister med avseende på dynamiken. Därmed är det ytterst viktigt att skapa goda förutsättningar för noggranna beräkningsmodeller som i ett projekteringsskede kan representera konstruktionernas dynamiska beteende. I denna rapport utfördes en jämförelseanalys mellan en FE-modell och en fältmätning, där Folke Bernadottes bro har använts som underlag. Syftet är att presentera skillnader och likheter i naturliga frekvenser och modformer baserat på jämförelseanalysen, samt belysa några av de viktigaste faktorerna bakom dessa. Resultatet visade för en kalibrerad FE-modell 11 % genomsnittlig skillnad för de naturliga frekvenserna och 99 % överensstämmelse med avseende på modformerna, där den mest väsentliga parametern i modellen var upplagsvillkoren., Today's planning and design of constructions is characterized by a resource utilization, environmental and economic thinking, where the result can lead to shortcomings with regard to dynamic behaviour. Thus, it is extremely important to create good conditions for accurate calculation models that in a design phase can represent the dynamic behaviour of the structures. In this report, a comparison analysis was performed between an FE-model and a field measurement, where Folke Bernadotte's bridge has been used as basis. The purpose is to present differences and similarities in natural frequencies and mode shapes based on the comparative analysis, and to highlight some of the most important factors behind these. The result showed for a calibrated FE-model an average difference of 11 % for the natural frequencies and 99 % agreement with respect to the mode shapes, where the most important parameter in the model was the support conditions.

Timber is a building material that is becoming more common and of interest for use in high-rise buildings. One of the reasons is that timber requires less energy input for the manufacturing process of the material compared to non-wood based materials. When designing high- rise timber buildings it is of great significance to understand the dynamic behavior of the structure. One method to obtain the dynamic properties is to use Operational Modal Analysis, which is based on the structural response from operational use. Finite element (FE) analysis is a tool which can be used for dynamic analysis for large structures. In this study an Operation Modal Analysis (OMA) was conducted on a four-story timber building in Växjö. A finite element model was created of the same building using commercial FE packages. Based on the mode shapes and natural frequencies obtained from the OMA, the FE model was fine-tuned. The purpose of this thesis is to gain knowledge of which parameters that might have a significant role in finite element modelling for a structural dynamic analysis. The aim is to develop a finite element model that accurately simulates the dynamic behavior of the tested building. It was shown from the result that is possible with an enough detailed FE model to capture the dynamic behaviour of a structure. The parameters that had the largest effect on the result can be pointed to the mass and the stiffness of the structure., Trä är ett byggnadsmaterial som börjar bli allt mer vanligt och är av intresse att använda som stommaterial för höga byggnader. En anledning till detta är att det krävs mindre energi i tillverkningsfasen för trä jämfört med stål och betong. Vid dimensionering av höga träbyggnader är det essentiellt att förstå byggnadens dynamiska egenskaper. För att ta fram en byggnads dynamiska egenskaper kan en metod som benämns Operational Modal Analysis (OMA) tillämpas vilken baseras på byggnadens rörelser vid daglig användning. Finita element (FE) metoden är ett verktyg som kan användas vid dynamisk analys för större byggnader. I detta arbete genomfördes en OMA för ett fyravåningshus med trästomme beläget i Växjö. Genom användning av kommersiella FE-mjukvaror togs en finita element modell av samma byggnad fram. Baserat på de egenfrekvenser och egenmoder erhållna från OMA, uppdaterades FE-modellen därefter. Syftet med detta arbete är att erhålla kunskap kring vilka parametrar som har betydelse vid FE-modellering med hänsyn till dynamisk analys. Syftet är även att validera den prototyp av datainsamlingsenhet som använts vid fältmätningen. Målet med arbetet är att ta fram en FE-modell som på ett korrekt sätt beskriver den testade byggnadens dynamiska beteende. Resultatet av arbetet påvisar att med en tillräckligt detaljerad FE-modell är det möjligt att erhålla en byggnads dynamiska egenskaper. De parametrar som har störst inverkan på resultatet är byggnadens styvhet och inkluderad massa.

The timber concrete composite (TCC) deck system is a new technology that consists of timber and concrete composite structures but remains uncommon in Malaysia. TCC is a structural system where timber beams and concrete slabs are combined to form a composite material, resisting tensile stress and compressive stress, respectively. The addition of concrete slabs protects timber beams from direct contact with water, which is crucial to ensure the durability of timber beams. Different types of connectors can be used to provide force exchange between concrete slabs and timber beams. This research was conducted to study the vibration behavior of timber-concrete composite deck systems with or without concrete topping. The deck was constructed using twenty pieces of sawn timber measuring 3.6m x 0.09 m with a concrete topping of 0.065m. Experimental tests were conducted using an electrodynamic shaker with a frequency range of 1 Hz to 200 Hz. The shaker was placed on a laminated deck as vertical force and 15 accelerometers were used as output data collectors. Me´scope and SAP2000 package were used for data analysis. The natural frequency values of the first mode shape with and without concrete topping based on Me´scope analysis are 12.8Hz and 16.9Hz, respectively. Meanwhile, the finite element modeling analysis shows that the frequency of the first mode shape with laminated deck without concrete topping is 11.4 Hz while the one with concrete topping is 16.2 Hz. The natural frequencies obtained from the experimental test and the modal analysis are greater than 8 Hz, thereby concluding that the TCC laminated deck system is suitable and comfortable for building occupants.

A mode shape is a specific pattern of vibration executed by a mechanical system at a specific frequency. Different mode shapes will be associated with different frequencies. The experimental technique of modal analysis discovers these mode shapes and the frequencies. In this paper modal analysis has been carried out to determine the mode shapes and the respective frequencies of perforated plates with regard to change in the dimension of the perforations and the distance between the perforations (pitch).

In most experimental investigations, the accelerometer mass effect is neglected since the accelerometer mass is small in comparison to the mass of the test construction. When a lightweight construction is examined, however, this impact is noticeable. The goal of this research is to see how mass affects thin plate vibration. The characteristics of interest were the natural frequency and its associated mode shape. Using finite element analysis, the thin plate simply supported boundary condition was studied. The mass was added to the plate and distinct sites were chosen for mounting. The mass has a considerable influence on certain of the structure's modes, while it has no effect on others, according to the findings. The mass, which was placed at the plate's highest deflection point, revealed significant variations in natural frequencies and their associated mode shapes. For the mass mounted at the nodal line of the specific mode, there are no notable changes in natural frequency or mode shapes. The influence of mass is found to be dependent on the position of the mass, the vibration mode, and the magnitude of the mass. &nbsp

For intermediate floors in residential and office buildings, as well as in parking garages and malls, there is a wide use of hollow core concrete slabs in Sweden today. Hollow core slabs are precast and prestressed concrete elements with cylindrical-shaped voids extending along the length of the slab. These structural elements have the advantage compared to cast-in-situ concrete slabs that they have a high strength, due to the prestressing, and that the voids allow for a lower self-weight. Additionally, the voids allow for a reduction in the use of concrete material. These characteristics offer possibilities to build long-span floors with slender designs. However, a consequence of the slenderness of the slabs is that such floors have an increased sensitivity to vibrations induced by various dynamic loads. In residential and office buildings vibrations are primarily caused by human activity, and therefore concerns related to the serviceability of such floors are raised. These vibrations are often not related to problems with structural integrity, but rather to different aspects of comfort of the residents or workers. The aim of this thesis is to provide additional information regarding the dynamic behavior of hollow core floors. An experimental modal analysis has been performed on an existing floor in an office building. The dynamic properties in the form of natural frequencies, mode shapes, damping ratios and frequency response functions were derived and analyzed from these measurements. Subsequently, several finite element models were developed, aiming to reproduce the experimental dynamic behavior of the studied floor. The measurements initially showed some unexpected dynamic responses of the floor. For this reason, more advanced methods of signal analyses were applied to the data. The analyses showed that the slab has some closely spaced modes and that the modes of the floor are complex to a certain degree. The finite element models were studied with different co, Håldäck i betong används idag i stor utsträckning som bjälklag i bostads- och kontorsbyggnader, liksom i parkeringsgarage och köpcentra. Håldäcksbjälklag består av prefabricerade och förspända betongelement, med cylindriska hål som sträcker sig i plattans längsriktning. Dessa konstruktionselement har fördelen, jämfört med platsgjutna betongplattor, att de har en hög hållfasthet på grund av förspänningen och att hålen möjliggör en lägre egenvikt. Dessutom gör hålen att en mindre mängd betongmaterial behövs. Dessa egenskaper ger möjligheter att bygga golv med långa spännvidder och slank design. En konsekvens av slankheten är emellertid att sådana golv har en ökad känslighet för vibrationer som orsakas av olika dynamiska belastningar. I bostads- och kontorsbyggnader orsakas vibrationer främst av mänsklig aktivitet, och därför finns det en del oro relaterad till sådana golvs brukbarhet. Dessa vibrationer är oftast inte relaterade till frågor om strukturell integritet, utan snarare till olika aspekter av boendes eller arbetares känsla av komfort. Syftet med detta examensarbete är att bidra till kunskapen om håldäcksbjälklags dynamiska beteende. En experimentell modalanalys har utförts på ett befintligt golv i en kontorsbyggnad. De dynamiska egenskaperna i form av egenfrekvenser, modformer, dämpning och frekvenssvarsfunktioner erhölls och analyserades med hjälp av dessa mätningar. Därefter utvecklades flera finita element modeller för att reproducera det experimentellt uppmätta dynamiska beteendet hos det studerade golvet. Mätningarna visade initialt något oväntade dynamiska responser från golvet. Av denna anledning applicerades mer avancerade signalanalysmetoder på datan. Analyserna visade att plattan har några moder inom ett litet frekvensintervall och att moderna till en viss grad är komplexa. De finita element modellerna studerades med olika konfigurationer. I synnerhet studerades effekten av modellstorleken, randvillkoren, materialegenskaperna och potentiella struktu

Unlike metal structure, composite structures don’t give any clue till the fatal final collapse. The problem is more complicated when applied load on the structure is aeroelastic in nature. Under such loading, composite laminate experiences stresses. The first layer failure happens when stresses in the weakest ply exceed the allowable strength of the laminate. This initial layer-based failure changes overall material characteristics. It is important now to degrade the composite laminate characteristics for the subsequent failure prediction. The constitutive relations are required to be updated by the reduction in stiffness. The rest of the undamaged laminates continue to take the load till the updated strength is reached. In the present work, layer wise progressive failure analysis under aeroelastic loading has been performed by the inclusion of different failure criteria which allow for the identification of the location of the failure. ANSYS APDL environment has been used to model geometry of helicopter rotor. Under the loading conditions, stresses are calculated in the blade. Using stress tensor and failure criteria, failure location and modes have been predicted. It has been found that failure starts at higher speeds and failure starts from the root chord and tend towards the tip chord., Aerospace Structures & Computational Mechanics

For intermediate floors in residential and office buildings, as well as in parking garages and malls, there is a wide use of hollow core concrete slabs in Sweden today. Hollow core slabs are precast and prestressed concrete elements with cylindrical-shaped voids extending along the length of the slab. These structural elements have the advantage compared to cast-in-situ concrete slabs that they have a high strength, due to the prestressing, and that the voids allow for a lower self-weight. Additionally, the voids allow for a reduction in the use of concrete material. These characteristics offer possibilities to build long-span floors with slender designs. However, a consequence of the slenderness of the slabs is that such floors have an increased sensitivity to vibrations induced by various dynamic loads. In residential and office buildings vibrations are primarily caused by human activity, and therefore concerns related to the serviceability of such floors are raised. These vibrations are often not related to problems with structural integrity, but rather to different aspects of comfort of the residents or workers. The aim of this thesis is to provide additional information regarding the dynamic behavior of hollow core floors. An experimental modal analysis has been performed on an existing floor in an office building. The dynamic properties in the form of natural frequencies, mode shapes, damping ratios and frequency response functions were derived and analyzed from these measurements. Subsequently, several finite element models were developed, aiming to reproduce the experimental dynamic behavior of the studied floor. The measurements initially showed some unexpected dynamic responses of the floor. For this reason, more advanced methods of signal analyses were applied to the data. The analyses showed that the slab has some closely spaced modes and that the modes of the floor are complex to a certain degree. The finite element models were studied with different co, Håldäck i betong används idag i stor utsträckning som bjälklag i bostads- och kontorsbyggnader, liksom i parkeringsgarage och köpcentra. Håldäcksbjälklag består av prefabricerade och förspända betongelement, med cylindriska hål som sträcker sig i plattans längsriktning. Dessa konstruktionselement har fördelen, jämfört med platsgjutna betongplattor, att de har en hög hållfasthet på grund av förspänningen och att hålen möjliggör en lägre egenvikt. Dessutom gör hålen att en mindre mängd betongmaterial behövs. Dessa egenskaper ger möjligheter att bygga golv med långa spännvidder och slank design. En konsekvens av slankheten är emellertid att sådana golv har en ökad känslighet för vibrationer som orsakas av olika dynamiska belastningar. I bostads- och kontorsbyggnader orsakas vibrationer främst av mänsklig aktivitet, och därför finns det en del oro relaterad till sådana golvs brukbarhet. Dessa vibrationer är oftast inte relaterade till frågor om strukturell integritet, utan snarare till olika aspekter av boendes eller arbetares känsla av komfort. Syftet med detta examensarbete är att bidra till kunskapen om håldäcksbjälklags dynamiska beteende. En experimentell modalanalys har utförts på ett befintligt golv i en kontorsbyggnad. De dynamiska egenskaperna i form av egenfrekvenser, modformer, dämpning och frekvenssvarsfunktioner erhölls och analyserades med hjälp av dessa mätningar. Därefter utvecklades flera finita element modeller för att reproducera det experimentellt uppmätta dynamiska beteendet hos det studerade golvet. Mätningarna visade initialt något oväntade dynamiska responser från golvet. Av denna anledning applicerades mer avancerade signalanalysmetoder på datan. Analyserna visade att plattan har några moder inom ett litet frekvensintervall och att moderna till en viss grad är komplexa. De finita element modellerna studerades med olika konfigurationer. I synnerhet studerades effekten av modellstorleken, randvillkoren, materialegenskaperna och potentiella struktu

Unlike metal structure, composite structures don’t give any clue till the fatal final collapse. The problem is more complicated when applied load on the structure is aeroelastic in nature. Under such loading, composite laminate experiences stresses. The first layer failure happens when stresses in the weakest ply exceed the allowable strength of the laminate. This initial layer-based failure changes overall material characteristics. It is important now to degrade the composite laminate characteristics for the subsequent failure prediction. The constitutive relations are required to be updated by the reduction in stiffness. The rest of the undamaged laminates continue to take the load till the updated strength is reached. In the present work, layer wise progressive failure analysis under aeroelastic loading has been performed by the inclusion of different failure criteria which allow for the identification of the location of the failure. ANSYS APDL environment has been used to model geometry of helicopter rotor. Under the loading conditions, stresses are calculated in the blade. Using stress tensor and failure criteria, failure location and modes have been predicted. It has been found that failure starts at higher speeds and failure starts from the root chord and tend towards the tip chord., Aerospace Structures & Computational Mechanics

Micromechanical Thermal Analysis utilizes microstring resonators to analyze a minimum amount of sample to obtain both the thermal and mechanical responses of the sample during a heating ramp. We introduce a modulated setup by superimposing a sinusoidal heating on the linear heating and implementing a post-measurement data deconvolution process. This setup is utilized to take a closer look at the glass transition as an important fundamental feature of amorphous matter with relations to the processing and physical stability of small molecule drugs. With an additionally developed image and qualitative mode shape analysis, we are able to separate distinct features of the glass transition process and explain a previously observed two-fold change in resonance frequency. The results from this setup indicate the detection of initial relaxation to viscous flow onset as well as differences in mode responsivity and possible changes in the primary resonance mode of the string resonators. The modulated setup is helpful to distinguish these processes during the glass transition with varying responses in the frequency and quality factor domain and offers a more robust way to detect the glass transition compared to previously developed methods. Furthermore, practical and theoretical considerations are discussed when performing measurements on string resonators (and comparable emerging analytical techniques) for physicochemical characterization.

Application of irregular mass configuration in modern design era of buildings is unavoidable in order to serve various building functionality. Discontinued and unsymmetrical mass applied on a structure could vary its dynamic behaviour. Thus, a regular geometry of 5-storey steel frame tower at 5 meter height is designed and constructed in Jamilus Research Centre laboratory, to investigate the dynamic characteristics in terms of natural frequencies and its mode shapes subjected to various mass orientations. A total of four steel blocks at 800 kg are placed in equivalent, ascending and alternating orientations on the 1st to 4th storey of the frame. Ambient vibration (AV) technique is used for dynamic characteristics evaluation. Uni-axial accelerometer sensors are aligned in bi-axial horizontal directions of North-South and East-West. ARTeMIS processing tool and Frequency Domain Decomposition (FDD) methods are used for modal parameters determination. Comparative findings are made between bare frame and mass action frame. Significant reduction of predominant frequency showed up to 37.79% between bare frame against frame in ascending mass orientation. Equivalent mass orientation shows the lowest percentage discrepancy percentage compared to others. Two translation mode shapes and torsional mode are illustrated by respective three predominant frequencies. Even though some changes have be found in predominant frequencies, but comparable mode shapes illustration are observed from all three frequency modes from all frame configurations.

The aim of the research has been to investigate the change of dynamic behavior of a Kaplan turbine runner when submerged in still water. More specifically, the effects of the added mass on the modes of vibration have been quantified. For that, the modes of vibration of the runner in vacuum, in air and in water have been simulated with a coupled Acoustic-Structural modal analysis and, from their comparison, the reduction of the natural frequencies and the possible changes of the mode shapes have been determined. The results show that the typically assumed invariance of all the mode shapes of a structure when submerged in a dense fluid is not fully accomplished in this particular geometry. And regards to the frequency reduction ratios, they are found to be similar for the first six modes with an average value of about 37%., This project has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 814958. The authors also wish to acknowledge Vattenfall for the support., Peer Reviewed, Postprint (author's final draft)

Micromechanical Thermal Analysis utilizes microstring resonators to analyze a minimum amount of sample to obtain both the thermal and mechanical responses of the sample during a heating ramp. We introduce a modulated setup by superimposing a sinusoidal heating on the linear heating and implementing a post-measurement data deconvolution process. This setup is utilized to take a closer look at the glass transition as an important fundamental feature of amorphous matter with relations to the processing and physical stability of small molecule drugs. With an additionally developed image and qualitative mode shape analysis, we are able to separate distinct features of the glass transition process and explain a previously observed two-fold change in resonance frequency. The results from this setup indicate the detection of initial relaxation to viscous flow onset as well as differences in mode responsivity and possible changes in the primary resonance mode of the string resonators. The modulated setup is helpful to distinguish these processes during the glass transition with varying responses in the frequency and quality factor domain and offers a more robust way to detect the glass transition compared to previously developed methods. Furthermore, practical and theoretical considerations are discussed when performing measurements on string resonators (and comparable emerging analytical techniques) for physicochemical characterization.

Micromechanical Thermal Analysis utilizes microstring resonators to analyze a minimum amount of sample to obtain both the thermal and mechanical responses of the sample during a heating ramp. We introduce a modulated setup by superimposing a sinusoidal heating on the linear heating and implementing a post-measurement data deconvolution process. This setup is utilized to take a closer look at the glass transition as an important fundamental feature of amorphous matter with relations to the processing and physical stability of small molecule drugs. With an additionally developed image and qualitative mode shape analysis, we are able to separate distinct features of the glass transition process and explain a previously observed two-fold change in resonance frequency. The results from this setup indicate the detection of initial relaxation to viscous flow onset as well as differences in mode responsivity and possible changes in the primary resonance mode of the string resonators. The modulated setup is helpful to distinguish these processes during the glass transition with varying responses in the frequency and quality factor domain and offers a more robust way to detect the glass transition compared to previously developed methods. Furthermore, practical and theoretical considerations are discussed when performing measurements on string resonators (and comparable emerging analytical techniques) for physicochemical characterization.

[EU] Dokumentu honetan balazta baten diskoaren analisi modal teorikoa eta esperimentala konparatzen dira. Analisi teorikoa elementu finituen metodoa erabiliz egin da ANSYS softwareari esker. Korrelazioa egiteko, berriz, BK Connect programa baliatu da, zeinetan aurretiaz egindako analisi esperimentaleko emaitzak dauden. Hortaz, ANSYS eta BK Connect-en arteko konexio hori ahalbidetzeko datu teoriko guztiak formatu unibertsalean idazten dituen programa bat garatu zen Fortran programazio lengoaian. Honi esker, emaitza teorikoak BK Connect-ek ireki dezakeen zenbait fitxategi sortu dira analisi esperimentalarekin lortutakoekin konparatu direnak. Izan ere, analisi esperimentaleko emaitzak zuzenak diren balioztatzeko Modal Assurance Criterion (MAC) deritzon korrelazio metodoa erabili da eta emaitzak grafikoki ere adierazi dira., [ES] En este documento se ha llevado a cabo la comparación teórica y experimental del análisis modal del disco de un freno. Para ello, haciendo uso del software ANSYS se ha hecho el análisis teórico utilizando el método de elementos finitos. Dicha correlación se ha llevado a cabo mediante el programa BK Connect, en el cual está guardado el análisis experimental previamente realizado. Por consiguiente, para posibilitar la conexión entre ambos, se ha desarrollado un programa mediante el lenguaje Fortran, el cual transforma los datos teóricos en formato universal. Así, se han creado varios archivos que pueden ser abiertos por BK Connect y que se han comparado con los datos experimentales. De hecho, para la validación de los datos experimentales se han comparado los datos mediante el llamado Modal Assurance Criterion (MAC)., [EN] In this document a comparison between the experimental and theoretical modal analysis of a disc of a brake is carried out. In order to do the theoretical analysis, the Finite Element Method have been used thanks to the software ANSYS. On the other hand, the program BK Connect has been used to make the correlation where the results obtained from experimental modal analysis are saved. Therefore, to make the connection between those two programs possible, a new program has been developed with Fortran, which creates some files with universal format. These files can be opened by BK Connect, so that the comparison with the experimental analysis can be done. In fact, using the Modal Assurance Criterion (MAC) the correlation has been made and the results have been represented in a graphic.

When simulating the vibration behaviour of large 2-stroke marine diesel engines the damping properties are an important parameter to be considered. Simulations only allow determining realistic vibration amplitudes if the engine’s damping characteristic is known. Modal damping ratios of reciprocating engines vary depending on which parts of the engine interact during oscillation and on how energy is dissipated while vibrating. Therefore different damping ratios can be expected for different engine mode shapes. For determining typical modal damping ratios of a diesel engine a methodology for an automated analysis of vibration measurement data was developed: After identifying N resonance peaks in a measured vibration spectrum a spectral curve corresponding to a simple mass-spring-damper system with N degrees of freedom is automatically fitted onto the measured curve by parameter optimization. At the end of this iterative process the damping properties of the substituting mass-spring-damper-system, whose curve adjusts most precisely to the measured spectrum, are attributed to the measured resonances. In addition to determining modal damping ratios and eigenfrequencies the procedure allows separating overlapping resonance peaks. The analysis process was applied on vibration measurement results of a series of different marine diesel engines and characteristic modal damping ratios could be determined for the engine’s principal mode shapes. Considering the determined modal damping properties when performing forced response simulations of the engine by modal superposition in the frequency domain allowed to achieve a higher accuracy in the calculated vibration amplitudes.

[EU] Dokumentu honetan balazta baten diskoaren analisi modal teorikoa eta esperimentala konparatzen dira. Analisi teorikoa elementu finituen metodoa erabiliz egin da ANSYS softwareari esker. Korrelazioa egiteko, berriz, BK Connect programa baliatu da, zeinetan aurretiaz egindako analisi esperimentaleko emaitzak dauden. Hortaz, ANSYS eta BK Connect-en arteko konexio hori ahalbidetzeko datu teoriko guztiak formatu unibertsalean idazten dituen programa bat garatu zen Fortran programazio lengoaian. Honi esker, emaitza teorikoak BK Connect-ek ireki dezakeen zenbait fitxategi sortu dira analisi esperimentalarekin lortutakoekin konparatu direnak. Izan ere, analisi esperimentaleko emaitzak zuzenak diren balioztatzeko Modal Assurance Criterion (MAC) deritzon korrelazio metodoa erabili da eta emaitzak grafikoki ere adierazi dira., [ES] En este documento se ha llevado a cabo la comparación teórica y experimental del análisis modal del disco de un freno. Para ello, haciendo uso del software ANSYS se ha hecho el análisis teórico utilizando el método de elementos finitos. Dicha correlación se ha llevado a cabo mediante el programa BK Connect, en el cual está guardado el análisis experimental previamente realizado. Por consiguiente, para posibilitar la conexión entre ambos, se ha desarrollado un programa mediante el lenguaje Fortran, el cual transforma los datos teóricos en formato universal. Así, se han creado varios archivos que pueden ser abiertos por BK Connect y que se han comparado con los datos experimentales. De hecho, para la validación de los datos experimentales se han comparado los datos mediante el llamado Modal Assurance Criterion (MAC)., [EN] In this document a comparison between the experimental and theoretical modal analysis of a disc of a brake is carried out. In order to do the theoretical analysis, the Finite Element Method have been used thanks to the software ANSYS. On the other hand, the program BK Connect has been used to make the correlation where the results obtained from experimental modal analysis are saved. Therefore, to make the connection between those two programs possible, a new program has been developed with Fortran, which creates some files with universal format. These files can be opened by BK Connect, so that the comparison with the experimental analysis can be done. In fact, using the Modal Assurance Criterion (MAC) the correlation has been made and the results have been represented in a graphic.

[EU] Dokumentu honetan balazta baten diskoaren analisi modal teorikoa eta esperimentala konparatzen dira. Analisi teorikoa elementu finituen metodoa erabiliz egin da ANSYS softwareari esker. Korrelazioa egiteko, berriz, BK Connect programa baliatu da, zeinetan aurretiaz egindako analisi esperimentaleko emaitzak dauden. Hortaz, ANSYS eta BK Connect-en arteko konexio hori ahalbidetzeko datu teoriko guztiak formatu unibertsalean idazten dituen programa bat garatu zen Fortran programazio lengoaian. Honi esker, emaitza teorikoak BK Connect-ek ireki dezakeen zenbait fitxategi sortu dira analisi esperimentalarekin lortutakoekin konparatu direnak. Izan ere, analisi esperimentaleko emaitzak zuzenak diren balioztatzeko Modal Assurance Criterion (MAC) deritzon korrelazio metodoa erabili da eta emaitzak grafikoki ere adierazi dira., [ES] En este documento se ha llevado a cabo la comparación teórica y experimental del análisis modal del disco de un freno. Para ello, haciendo uso del software ANSYS se ha hecho el análisis teórico utilizando el método de elementos finitos. Dicha correlación se ha llevado a cabo mediante el programa BK Connect, en el cual está guardado el análisis experimental previamente realizado. Por consiguiente, para posibilitar la conexión entre ambos, se ha desarrollado un programa mediante el lenguaje Fortran, el cual transforma los datos teóricos en formato universal. Así, se han creado varios archivos que pueden ser abiertos por BK Connect y que se han comparado con los datos experimentales. De hecho, para la validación de los datos experimentales se han comparado los datos mediante el llamado Modal Assurance Criterion (MAC)., [EN] In this document a comparison between the experimental and theoretical modal analysis of a disc of a brake is carried out. In order to do the theoretical analysis, the Finite Element Method have been used thanks to the software ANSYS. On the other hand, the program BK Connect has been used to make the correlation where the results obtained from experimental modal analysis are saved. Therefore, to make the connection between those two programs possible, a new program has been developed with Fortran, which creates some files with universal format. These files can be opened by BK Connect, so that the comparison with the experimental analysis can be done. In fact, using the Modal Assurance Criterion (MAC) the correlation has been made and the results have been represented in a graphic.

When simulating the vibration behaviour of large 2-stroke marine diesel engines the damping properties are an important parameter to be considered. Simulations only allow determining realistic vibration amplitudes if the engine’s damping characteristic is known. Modal damping ratios of reciprocating engines vary depending on which parts of the engine interact during oscillation and on how energy is dissipated while vibrating. Therefore different damping ratios can be expected for different engine mode shapes. For determining typical modal damping ratios of a diesel engine a methodology for an automated analysis of vibration measurement data was developed: After identifying N resonance peaks in a measured vibration spectrum a spectral curve corresponding to a simple mass-spring-damper system with N degrees of freedom is automatically fitted onto the measured curve by parameter optimization. At the end of this iterative process the damping properties of the substituting mass-spring-damper-system, whose curve adjusts most precisely to the measured spectrum, are attributed to the measured resonances. In addition to determining modal damping ratios and eigenfrequencies the procedure allows separating overlapping resonance peaks. The analysis process was applied on vibration measurement results of a series of different marine diesel engines and characteristic modal damping ratios could be determined for the engine’s principal mode shapes. Considering the determined modal damping properties when performing forced response simulations of the engine by modal superposition in the frequency domain allowed to achieve a higher accuracy in the calculated vibration amplitudes.

During flight, insect wings bend and twist under the influence of aerodynamic and inertial forces. We tested whether wing resonance of honeybees (Apis mellifera) matches the wingbeat frequency, against the 'stiff element' hypothesis that the wing's first longitudinal mode exceeds the wingbeat frequency. Six bees were immobilized with their right wing pair outspread, and stimulated with a shaker while the normal modes were recorded with a scanning Doppler laser vibrometer. The lowest normal mode of the wings was the first longitudinal bending mode and, at 602±145 Hz, was greater than the wingbeat frequency of 234±13.9 Hz. Higher-order normal modes of the wing tended to incorporate nodal lines in the chordwise direction of the trailing edge, suggesting that their mode shape did not strongly resemble wing deformation during flapping flight. These results support the stiff element hypothesis for Apis mellifera.

During flight, insect wings bend and twist under the influence of aerodynamic and inertial forces. We tested whether wing resonance of honeybees (Apis mellifera) matches the wingbeat frequency, against the 'stiff element' hypothesis that the wing's first longitudinal mode exceeds the wingbeat frequency. Six bees were immobilized with their right wing pair outspread, and stimulated with a shaker while the normal modes were recorded with a scanning Doppler laser vibrometer. The lowest normal mode of the wings was the first longitudinal bending mode and, at 602±145 Hz, was greater than the wingbeat frequency of 234±13.9 Hz. Higher-order normal modes of the wing tended to incorporate nodal lines in the chordwise direction of the trailing edge, suggesting that their mode shape did not strongly resemble wing deformation during flapping flight. These results support the stiff element hypothesis for Apis mellifera.

In many areas of engineering such as telecommunications industry, lenses and optical cooling, waveguiding and the ability to control wave propagation is necessary. Phononic Crystals (PnCs) influence the propagation of mechanical waves by their periodic variation in elastic impedances. Depending on Lattice type and inclusion's spacing, one can manipulate the frequencies that are blocked or allowed to transmit through the crystal in a particular direction. In this work, two dimensional PnCs plates are design and also numerically and experimentally demonstrated. Finite Element Analysis (FEA) was performed to study the dispersion behavior and eigenmodes of a PnC. The simulations show the existence of a complete bandgap, thus acoustic PnC devices such as cavity, resonator and waveguide are created accordingly by introducing a line defect to the crystal. The experimental response of the devices was then measured by fabricating and then testing them. These results show excellent agreement with the FEA. For the first time waveguide and 90áµ’ bend is designed that have several isolated modes in the bandgap with transmission efficiencies above 90% for a specific frequency range. In this seminar also a few novel patents will be introduced. We consider a two-dimensional periodic square array of the air holes in a finite aluminum medium. The defect introduced to the crystals are acting as local acoustic resonances/guiding with the substrate and lead to the possibility of finding a low-frequency confined acoustic waves or guided modes. Studying the mode shapes will help to shed light on the origin of BG formation and as the results BG optimization. The numerical and experimental results presented here are related to the case of Aluminum-air devices, but the conclusions remain valid for other materials and compositions as well.