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A novel model reduction method for viscously damped structures with statically determinate interfaces, such as spacecraft flexible appendages, is proposed. The paper presents a derivation of the complete complex modal expansion of the interface dynamic stiffness of these structures. Based on the identity relation for all complex modes, which is obtained during the derivation, it is found that the interface acceleration impedance can be expressed as a rational fraction with high accuracy using only low-order complex modes. Using this rational fraction as an approximation model, numerical results of the frequency response can be fitted. The fitted interface acceleration impedance can be applied to real-time control as a reduced model in the form of a transfer function. Furthermore, it can be transformed into the form of system matrices by introducing auxiliary variables, which then participate in the dynamic analysis of the assembly. The reduction process circumvents complex modal analysis and necessitates only the results of frequency responses. Thanks to the powerful ability of conventional finite element software to perform frequency response analysis, this reduction method can be used for large-scale complex models in actual engineering applications. [ABSTRACT FROM AUTHOR]

In aerospace engineering, the existence of cracks highly alters the mechanical behaviors of structural components. As a new class of key structural components, functionally graded material (FGM) rectangular plates with an interior/side crack are focused on in this study. New analytical free vibration solutions are put forward for such cracked FGM plates. First, a cracked plate is decomposed into several subplates with the necessary continuity conditions to address the physical discontinuity issue caused by the crack. The challenge then becomes deriving analytical free vibration solutions for each subplate. To accomplish this task, a symplectic superposition method (SSM) is developed to deal with FGM rectangular plates with various boundary conditions, including the complex continuity conditions. The SSM eliminates the need for a predefined solution form, and its solution procedure, including variable separation and eigen expansion, is mathematically rigorous. Afterward, the analytical solutions obtained via the SSM are integrated to serve as the final free vibration solution of the cracked FGM plate. Comprehensive results based on the obtained analytical solutions, including natural frequencies and vibration modes, are presented and validated. The solutions are further used to investigate the effects of some important parameters, such as crack length and crack location. [ABSTRACT FROM AUTHOR]

This paper proposes a dynamic simulation method for solving balloon shapes. The mass-spring-damping model is used to discretize two-dimensional generatrixes and three-dimensional membrane surfaces, respectively. We solve two-dimensional/three-dimensional ascent shapes at different zero-pressure heights and numerically simulate mushroom cloud shapes that occur during the balloon ground launch. The typical rapid transition feature of the mushroom cloud shape at the waist is depicted. In addition, a preliminary numerical simulation study was conducted for the pumpkin superpressure balloon deployment instability problem. The Calladine instability critical curve for constant angle design lobes is compared and validated for different gore numbers and lobe angles. Further, simulations were carried out on fully inflated shapes of two derived superpressure balloon designs developed by the Japan Aerospace Exploration Agency/Institute of Space and Astronautical Science, namely, the Tawara intermediate cylindrical segment balloon and the diamond-shaped tendon balloon. We verify the ISAS conclusion that the diamond-shaped tendon balloon has a cylindrical shape when fully inflated. Finally, a preliminary simulation study was carried out on the deployment shape of four ballonet architectures in the superpressure balloon. The proposed method for solving various types of balloon shapes based on the mass particle method is simple and efficient, and it has been well applied in our actual balloon engineering. [ABSTRACT FROM AUTHOR]

Additive manufacturing enables the deposition of material in the near-net shape at any desired location on the base plate or shell to improve the structural performance by tailoring the buckling and/or vibration mode shapes. In this study, a stiffened plate with arbitrarily shaped stiffeners is modeled using a nonconformal mesh-based finite element model. Six degrees of freedom are considered for each node of the plate and the stiffener finite element models to enable the couplings between the plate's and stiffeners' in-plane and out-of-plane motions. Displacement compatibility is enforced at the interface between the plate and the stiffeners where several skin-stringer connection approaches, including inverse isoparametric mapping algorithm (IIMA), radial basis function, and thin-plate spline function, are used. Various complex models available in the literature are employed for evaluating the skin-stringer connection approaches. Research studies show that the IIMA-based nonconformal mesh modeling can generate a sparse displacement approximation matrix, which makes it an efficient approach for nonconformal mesh-based modeling. For the stiffened plate with higher stiffeners, the present results agree well with those obtained from the Abaqus/CAE conventional conformal mesh and mesh tie constraint-based nonconformal mesh modeling results, but yield better results than the Abaqus/CAE wrapping mesh approach. [ABSTRACT FROM AUTHOR]

The safety lifetime analysis under the required time-dependent failure probability (R-FP) constraint is essential to ensure structure service safety, but existing methods are unaffordable for solving the safety lifetime under a small R-FP constraint. For this issue, a novel method is proposed by combining a two-phase subset simulation with an adaptive kriging model (TP-SS-AK). The innovations of the TP-SS-AK include three aspects. First, it creatively transforms the safety lifetime under a small R-FP constraint into that under a large conditional R-FP constraint by subset simulation, which can greatly improve efficiency because the large conditional R-FP constraint only needs a small candidate sample pool for searching the safety lifetime. Second, by deducing the misclassification probability of the time-dependent structure state in the first phase, the first new learning strategy is established to train the kriging model of the time-dependent performance function and further determine a reasonable lifetime search interval efficiently. Third, by deriving the misclassification probability of the first failure instant, the second new learning strategy is constructed to efficiently update the kriging model in the second phase and further search the safety lifetime. Because the proposed TP-SS-AK combines the advantages of the two-phase subset simulation and two new learning strategies, it is superior to the existing methods in efficiency, and its superiority is verified by the examples. [ABSTRACT FROM AUTHOR]

A computational model has been developed to analyze composite pi joints subjected to pulloff and side-bend loading. A discrete damage modeling approach is used to capture the interactions between intralaminar damage (matrix cracking) and interlaminar damage (delamination). Cohesive element interlayers and matrix-crack elements are governed by the same mixed-mode traction-separation formulation, resulting in a unified damage framework. The finite element model was calibrated using experimental data from pristine and defective joints. In the calibration process, in situ cohesive material properties were backcalculated from pulloff tests such that the accurate prediction of structural response and the damage evolution of pi joints were possible. Computational predictions for both pulloff and side-bend loading are shown to agree well with experimental results for joints subjected to pulloff and side-bend loading. [ABSTRACT FROM AUTHOR]

This paper focuses on how to establish an accurate numerical model of penetrator penetration into the lunar soil and study the process of penetration. The lunar soil simulant was prepared according to published literature, and its plastic parameters were obtained by triaxial compression test. To determine the material model and parameters of the lunar soil simulant in numerical simulation, the corresponding numerical simulation was carried out for the triaxial test. Under the comprehensive consideration of accuracy and computational efficiency, the applicability of four numerical algorithms, including finite element method (FEM), arbitrary Lagrangian-Eulerian, smoothed particle hydrodynamics (SPH), and SPH-FEM, in the penetration simulation is evaluated. Finally, SPH-FEM is the optimal algorithm for the numerical simulation of the penetrator penetrating lunar soil. The convergence of the penetration model is tested. Finally, an accurate numerical model of the penetrator penetrating lunar soil is obtained. Then, the effects of incident velocity, incident angle, and angle of attack on penetration performance are studied, respectively, which provide reference for the design and process control of the penetrator project. [ABSTRACT FROM AUTHOR]

There are two methods commonly used to determine the effectiveness of a bullet-resistant door: one involves the use of sensors attached to various locations to detect cracking following impact and the other employs software simulations. In this study, we utilized the finite element method (FEM) analysis software MSC.Patran to perform stress analyses on a designed bullet- resistant door, subjecting it to various external forces. Utilizing the FEM simulation method eliminates the need for attached sensors to detect the effects of impacts. The focus is on developing a shock-loaded door that can withstand various impacts with minimal visible damage or deformation. In this study, we primarily examine the effects of different impacts on a designed bullet-resistant door through simulation using MSC.Patran's FEM. The software was employed to simulate and compute stress and displacement distributions, as well as the response force of the entire door structure, while assuming various conditions such as steel structure, welding strength, and material, among others, under different impact conditions. The impacts were generated by a 125 kg and 8 inch armor-piercing projectile, a car, or a solid steel ball, and an earthquake with a magnitude of roughly 6.4 was added to the stress conditions to analyze and simulate the stresses. The results of different impacted objects were discussed. The findings revealed that, under the aforementioned conditions, the designed door structure could effectively withstand external impacts without damage. On the basis of the analysis results, it was determined that the steel panel, steel structure, and latch of the bullet-resistant door were capable of resisting the combined impacts of the specified foreign objects. [ABSTRACT FROM AUTHOR]

The dam is considered a huge structure that has multiple purposes in the life of a human. The most important role of a dam is the production of electricity, and the storage of a huge quantity of water. Therefore, it is very important to be vigilant in the studies made for it. Lebanon has indeed been designated as a seismicity country. However, the number of dams is increasing due to several natural consideration. Mseilha dam is an executed medium arch dam, which faced several problems during and after construction. The initial problem that faced a dam is the seismic force. This natural force is very dangerous for any structure, especially for a dam. It could increase the existing concrete stresses. These stresses will cause the development of cracks all along the dam. Once the concrete shows cracks, its resistance will decrease, and it will become more vulnerable to external effects. Several studies were made to fortify it and make it resistant to seismic force. To show the major effect of this force, two methods ‘pseudo-static’ and ‘response spectrum’ were applied to a medium arch dam. Therefore, to evaluate the performance of these two methods, the dam is modelled using finite element software. The obtained results show the importance of using the appropriate model in the design of such dams without taking the appropriate model. HIGHLIGHTS Highlight on one of the major problems that affect the stability of medium dam.; Clarify how to analyze this catastrophic problem and prevent the losses (Humans life and economic way).; Illustrate, through a comparison between two analysis methods, how to simulate numerically such severe problem.; Encourage the researches to take into consideration all the existed forces during analysis and design for all dam types.;

Attempting to predict the physical response of a complex system under realistic conditions is extremely challenging. In this work, a parametric reduced-order model (PROM) of a bladed disk is briefly presented that allows for the quick and efficient modeling of rotational speed effects and mistuning effects in bladed disks. This computational model is tuned to match experimental data. The tuned PROM is then investigated through a parametric study. Three internal parameters investigated are i) forcing magnitude, ii) mistuning value magnitude, and iii) damping magnitude, and four external parameters are iv) forcing location, v) forcing radius, vi) probe placement error, and vii) arrival time error. These parameters are common in the structural analysis of turbomachines. Each internal parameter is increased and decreased by 10, 20, and 50%, while external parameters are changed by varying amounts due to geometric and practical limitations. The model is time integrated to simulate the conditions present in the experimental test rig. The maximum blade amplitudes are then compared to the baseline case and analyzed. The damping, followed by the forcing, is shown to cause the greatest impact on the final system response. This indicates a greater need to accurately measure the damping compared to other parameters. [ABSTRACT FROM AUTHOR]

Affected by the uncertainties caused by cable cutting and assembly errors, material performance dispersion, and truss deformation, the dual-surface accuracy of a mesh antenna cannot satisfy the design requirements. However, the existing methods can only adjust the accuracy of a single surface. This paper studies a method for adjusting coupled dual-surface mesh antennas considering uncertainties. Dual-reflector mesh antennas use both the front and rear reflectors for sensing, and both surfaces have shape accuracy requirements. First, an interval model updating method based on sensitivity analysis is proposed to obtain an updated interval parameters model group, which can accurately represent the relationship between adjustment cable length and surface accuracy. Then, an interval optimization function for the coupled dual-surface accuracy is established to get optimal adjustment amounts, which is solved by using the fast elitist nondominated sorting genetic algorithm (NSGA-II). Meanwhile, a kriging model is introduced to improve the optimization efficiency. Finally, the AstroMesh antenna is taken as an example to verify the validity of the proposed method. The results show that both the front and back net accuracies can be improved after adjustment, proving the proposed method's feasibility. [ABSTRACT FROM AUTHOR]

This paper presents a multidisciplinary structural optimization approach to design separation nuts with low-level pyroshock responses for aerospace. A parametric modeling method is developed to automatically construct a multibody finite element model for separation nuts according to the predefined structural parameters. A new explicit dynamics analysis workflow tailored to separation nuts is proposed to simulate the pyroshock environment efficiently. Based on a backpropagation neuron network technique, certain surrogate models are established to describe the equivalence relationship between the structural parameters and the multidisciplinary structural responses including the pyroshock, the bending stiffness, and the structural weight. Finally, a pyroshock minimization problem with the constraints of structural weight and bending stiffness is solved by using a genetic algorithm, resulting in an optimized low-pyroshock separation nut design. The comparison between the optimized structure and a reference structure shows the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

A dam is one of the oldest and largest buildings in the world. This structure is usually constructed to intercept flows, store water, and produce energy. Dams' foundations should really be rocky and robust enough to preserve their rigidity. Despite the great benefits of these structures, they are exposed to the risk of collapse. Two basic problems can confront a gravity dam; the first one is the uplift pressure load that could raise the danger of reversing the dam. The second one is the ground water flow, which can lift the soil under dam. Moreover, cracks are commonly formed in dams after construction. These cracks might produce several complications in the dam structure. Several investigations have shown the influence of the injected veil that made the dams stronger. This study shows the numerical results of the injection influence on a gravity dam. Finite element software is used to check up the best location of the injected veil and the maximum favorable depth. The obtained numerical results show the major effect of the veil injection on the uplift pressure force, the ground water values, and the flows pass under the gravity dam. HIGHLIGHTS The impact of this research can be summed up in these points.; Highlight on one of the major problems that affect the stability of gravity dam.; Clarify how to solve this problem and prevent the losses in different levels (Humans life and economic way).; Illustrate in an easy numerical method how to solve such severe problem.; Encourage the researchers to use the veil injection system in other dam types.;

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In reinforced concrete structures, the beam-column connection area has a considerable influence on the behavior of the structure. The use of fiber-reinforced polymer FRP to strengthen the connections in the Reinforced structure can be one of the solutions to transform this area, thus improving the behavior of the structure, which is achieved through the use of fiber-reinforced polymer of carbon to achieve high-strength concrete beam-column connections Investigations have been conducted using finite element modeling. The concrete damage plasticity model has been used to analyze the model. The results show that the bearing capacity has developed considerably, but the ductility is also significantly reduced. The study also evaluated the qualities of various reinforcement models and proposed the most effective reinforcement model. The use of fiber-reinforced polymer in the flex zone with fibers oriented at forty-five degrees in the shear zone of the joint showed the most significant changes in behavior. The demolition of reinforced concrete beam-column joints is a sudden failure without prior notice, since the collapse of the column and the connection before the break of the beam are undesirable, their occurrence can cause irreparable damage.

The deterioration of environment, the aggravation of energy crisis and the exhaustion of non renewable energy promote the development of green new energy. Among them, wind power generation has become a research hotspot in the field of new energy at home and abroad. In this paper, the deflection double stator switched reluctance generator (DDSSRG) is taken as the research object, the basic modelling and analysis of DDSSRG are carried out, and the magnetic field of the generator is analyzed by using the finite element software. The structure of the generator is optimized by using the central composite design method (CCD). Finally, the experimental platform of the generator is built to verify the feasibility of the theory in structure.

We present Seismo-VLAB (SVL), a new open-source, object-oriented finite element software designed to optimize meso-scale simulations in the context of structural and geotechnical engineering. To this end, state-of-the-art tools and parallel computing capabilities required for efficient modeling of soil–structure interaction and wave propagation in heterogeneous half-spaces are included. For example, perfectly matched layer, domain reduction method, dynamic nonlinear solvers, cutting edge parallel linear system solvers, domain decomposition method, and a series of plasticity models are some of the features available in SVL. In this work, we present the numerical implementation and software structure so enthusiastic developers can contribute to this open-source project and showcase some software capabilities using an illustrative example.

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cylindrical steel tanks have been used to store various materials and fluids. From a geometrical point of view, steel tanks have a very low thickness compared to the other two dimensions and thus are classified as thin-walled structures. Nowadays, the use of thin-walled structures is very popular. The main reason for this is the low weight and high strength of such structures. In order to reduce the weight and cost of the structure, cylindrical steel tanks can be made with variable thicknesses in height. Changing the thickness of the tank's wall has been considered to reduce weight and economic requirements. Settlement is one of the important issues that must be considered for reservoirs. In general, foundation settlement occurs under the tanks’ walls due to special soil properties, which are divided into three general components: Uniform, Tilt, and Local settlement. In the meantime, local settlement has the greatest impact on the tank’s shell, although it has the lowest value. This component can cause large radial displacements, shell buckling, and even tank’s failure. In this study, 17 steel cylindrical tanks with or without a reinforcing ring on the upper part were modeled in ABAQUS software and placed under local settlement at the edge of their floor. The values of settlement, equivalent buckling load, and their radial deformation were compared to each other. S4R elements (a four-node element with reduced curvature double integral) were used to mesh the tanks. The results of nonlinear analysis indicate that buckling occurs at the lower part of the shell. Moreover, the local settlement causes severe buckling at the site and perpendicular direction of the settlement. Appropriate and acceptable behavior of tanks with variable thickness in comparison with constant thickness and the hardening ring can have positive effects on the buckling behavior of tanks.

The geometrically nonlinear random vibration response of stiffened laminated plates under acoustic excitation is carried out by using the equivalent linearization (EL) technique combined with the reduced-order model and the finite element method. The nonlinear equations of motion of stiffened laminated plates are obtained based on large deflection finite element formulation. The proper orthogonal decomposition technique is used to select the modal basis, and a reduced-order model of the structures is established. Based on the force error minimization approach, the EL formulation for solving nonlinear random vibration response is derived. Then the EL technique is incorporated into finite element software NASTRAN by the direct matrix abstraction program, and the direct matrix abstraction program also realizes the iterative process of determining the modal equivalent linear stiffness matrix. Then, the statistical dynamic response results obtained by EL and linear method are compared and analyzed. It is verified that the proposed method has high accuracy and efficiency, and it can be applied to the geometric nonlinear random vibration response analysis of stiffened laminated plates. The results show that geometric nonlinearity plays an important role in the vibration response of stiffened laminated plates, especially under high sound pressure loads. [ABSTRACT FROM AUTHOR]

Under the condition of rainfall, the decrease in shear strength of a slope is one of the important factors that lead to the slope instability. Infiltration of rainwater into the slope is a dynamic process, and the water content or saturation of soil will change continuously. Therefore, it is of great significance to study the shear strength of soil under dynamic environment for real-time evaluation of the stability of soil slope under rainfall conditions. Based on the strength theory of unsaturated soil, this paper takes the expansive soil in the Jianshanying area of Guizhou Province as the object, combines the shear test data to establish the fitting relationship between the shear strength index and water content of the expansive soil, and puts forward the shear strength formula with water content as the variable. Based on the secondary development technology of ABAQUS platform, USDFLD subroutine is compiled to import the shear strength formula of the Jianshanying expansive soil, and the influence of strength attenuation and gravity change caused by the change of soil moisture content on the stability of the expansive soil slope under the condition of rainfall are also explored. The results show that with the increasing water content of the expansive soil, the particles in the soil expand by the absorbing water, the particle spacing decreases, and the adhesion between the mineral particles increases gradually. Until the water filling suction of the aggregate space decreases, the adhesion decreases rapidly, and the shear strength of the expansive soil decreases generally, in which the cohesion increases first and then decreases, and the internal friction angle decreases. The secondary development technology of ABAQUS software can realize the relationship of soil parameters with the change of water content, which provides a new technical means for the finite element analysis of unsaturated soil slope under the condition of rainfall.

Ductility and energy dissipation capacity of the beam column joints are the two prominent characteristics which govern the stability of the entire structure constructed in the seismic prone areas. In this paper, the effect of potassium-activated geopolymer concrete in the exterior beam column joint application is investigated under low frequency cyclic loading. Numerical analysis has been done by using the finite element software Abaqus and compared with the experimental work. From the load deformation relationship, parametric studies are carried out in the aspects of ductility, stiffness degradation, energy dissipation capacity, drift ratio and cracking pattern. The use of potassium-activated geopolymer technology in the exterior beam column joint application resulted in the improved ductility, energy dissipation capacity with superior ultimate load carrying capacity of 1.05% over conventional cement reinforced concrete beam column joints with special confining reinforcement confirmed by IS 13920 due to the enormous polymerization activated by high molecular potassium ions. There is an improved energy dissipation capacity of 2.78% of potassium-based geopolymer specimen resulting in lesser number of non-structural cracks and 11.26% more deformation under 11.96% enlarged drift ratio than the conventional reinforced concrete specimen. From the observed results, it is clearly noted that the implementation of potassium-activated green polymer technology in the beam column joints possessed enhanced ductility characteristics to protect the structure susceptible to seismic environment and resulted in innovative, economical and sustainable mode of seismic-resistant building construction. [ABSTRACT FROM AUTHOR]

Due to the seismic coupling effect, there is a big gap between the test results and the actual value, and the reliability is not high. Therefore, a test method for the vibration response of building curtain wall under the coupling effect of earthquake is studied. According to the relationship between the glass curtain wall and the main structure of the building, the differential equations of vibration response of the building curtain wall were constructed. During the process, the building and the curtain wall were divided, and the vibration response of the structural floor was obtained. Then, the vibration response of the floor was input into the curtain wall unit system between the floors, and the glass curtain wall response spectrum was established, and the vibration equation of the curtain wall was determined based on these. Taking Wuhan Railway Station as the study object, the finite element numerical value analytical model of the object was constructed by finite element software ANSYS14.0, and the influence of the natural vibration period of the structure, the natural vibration period of the curtain wall system, and the ground vibration on the coupled dynamic response of the curtain wall was studied. The results show that the vibration response of the glass curtain wall under seismic coupling is either amplified or weakened. The acceleration peak of the curtain wall usually appears when the two or three of the curtain wall natural vibration period, the structural natural vibration period, and the ground vibration period are close. Among them, the most dangerous situation is that the three are close. When the seismic magnitude is up to 9 degree, the structural stress of the curtain wall is less than the allowable value of the material, and it can be seen that the building structure is safe under this situation. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Experimental measurements of electrical machine performances reveal a significant difference between simulations and measurements. It is known that the manufacturing processes of machines, particularly, the cutting of core laminations adversely affects material properties. The current techniques for considering the effects of cutting lack accuracy, computation efficiency and applicability for finite element (FE) software. This study proposes a method to model the variation in the magnetic properties of electrical steel due to cutting based on a non‐equal multi‐slice technique. In this work, the method has been validated and implemented on a FE permanent magnet synchronous motor model. Also, the proposed method has been compared with the single‐layer method. [ABSTRACT FROM AUTHOR]

Copyright of Advanced Engineering Science / Gongcheng Kexue Yu Jishu is the property of Advanced Engineering Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

For making rivet and bolt connections, making a hole is necessary. While basic S-N graph can be extracted from design documents, analysis of stress can be used for two different approaches. The first approach is the theoretical derivation of analytical relations with simplified assumptions like planar stress or uniform bolt load distribution. The other one is the numerical simulation using robust codes like Abaqus software. By using these two approaches, residual stress distribution around the hole can be extracted in various conditions. In this experiment, an aluminium 2024-T3 plate with 3.2 mm thickness is considered. The stress analysis results and basic S-N graph were combined and discursive S-N graphs were obtained for different cold-expanded bolted holes. These graphs were compared with experimental data in several steps. First, the bolt fastening was considered. In the second step, cold expansion was considered and in the final step, the effects of fastening bolts and nuts and cold expansion was considered simultaneously. At last, a comparison between various steps was drawn. The results of this study showed that this new analytical method on distribution of residual stresses around cold expansion holes is as effectiveness as old methods.

Dynamic analysis of beam-tip mass systems is a significant issue in terms of providing successful design of mechanisms such as robot arms and manipulators. In the relevant literature, uniform beams have been mostly considered for the free vibration analysis of these systems whereas the number of studies using nonuniform beam is limited. Furthermore, center of tip mas is, in general, coincident with the attachment point of the beam, and the tip mass is assumed to be a point mass. This research concerns a non-uniform beam with a three dimensional rigid tip mass whose center of gravity is not coincident with the attachment point of the beam and subjected to both torsional and flexural deformations in two orthogonal planes. A semi-numerical method called Multi-Step Differential Transform Method (MDTM) is employed for the solution of governing equations of the system. Natural frequencies and mode shapes of the system are obtained for two different boundary conditions, i.e. the left end clamped or free. The influence of tip mass dimensions, beam length and taper ratio on the natural frequencies are studied, and the well-known finite element software (ANSYS) is employed to compare the results and confirm the accuracy of the model. It is proved that results obtained by MDTM and ANSYS are sufficiently close to each other. [ABSTRACT FROM AUTHOR]

The single crystal diamond chisel-edge tool is used to machine the 79 g/mm echelle diffraction grating, which is used as the research background. DEFORM-3D finite element software is used to simulate the mechanical ruling grating processing, and the influence of the parameters of the ruling tool on the squeezing force of aluminum film material is obtained. By analyzing the flow law of several sampling points in the groove-shaped over-squeezing region, the slip deformation characteristics of the aluminum film during the groove-shaped over-squeezing are clarified. Moreover, the velocity and stress field of aluminum film are analyzed under groove over-squeezing phenomenon. Therefore, it provides a basis for predicting the phenomenon of groove-shaped over-squeezing in the mechanical ruling grating processing. [ABSTRACT FROM AUTHOR]

In order to investigate the mechanical behavior of systems with complex architecture and a large number of contacting bodies, a finite element software, named LiToTac, has been developed by using the object-oriented programming technique. This software, with an interactive graphical user interface, is able to handle highly non-linear problems including multiple contacts and large deformation. More importantly, the contact detection based on a hybrid three-stages methodology can be performed automatically, which is more efficient than the common strategies of pre-defining contact zones in commercial FEM software like ANSYS, ABAQUS, etc. In addition, the contact solver in LiToTac is portable between dynamic and quasi-static codes and can accurately solve contact coupled with friction in a reduced system. Several numerical examples are carried out to illustrate the functionality and capacity of the software package. [ABSTRACT FROM AUTHOR]

Anticorrosion coatings are commonly applied to prevent rust-based corrosion in transmission towers. Unfortunately, anticorrosion coatings may drip onto the surface of composite insulators during the construction process, which is likely to do harm to operation characteristics of composite insulators. This Letter was conducted to determine the influence of anticorrosion coatings on composite insulator performance. The mechanical properties, hydrophobicity, hydrophobic transfer, and flashover voltage of high-temperature vulcanised (HTV) silicone rubber specimens with and without the coating were investigated in detail. Appropriate solutions for avoiding unwanted effects on insulator performance are proposed accordingly. The influence of coating on the pollution flashover voltage of the composite insulator was also determined by changing the type, area, and shape of coating attached to the insulator surface. Finite element software was also used to analyse the effects of coatings on the electric field distribution of the composite insulator. The coating slightly affects the mechanical properties of HTV silicone rubber, but significantly impacts its hydrophobicity and hydrophobicity transfer. The pollution flashover characteristics of test composite insulators covered with the anticorrosion coating are also worst than those without coating.