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This paper presents a numerical study of a road barrier subjected to a bus crash test. The authors focus on the proper description of a barrier material model. Material model parameters are verified according to a simulated forming process. The solution uses modeling and simulation methods, as well as the finite elements method implemented with LS-DYNA software. The obtained results show that defining a proper road barrier model must consider the manufacturing process. Intensive plastic deformation leads to a significant increase in yield stress only in areas where the highest strain is observed during the forming process. The barrier model is divided into three zones, each of which have material properties characterized by different constants. The described construction, which uses homogenous material, is much more deformed and flatter than that of the improved model. Comparison with the experimental results shows that the new model better describes barrier deformation. In addition, deformation of the barrier under impact is evaluated according to European regulations (EN 1317). In comparison to the performed bus crash test, the crash test parameters obtained in the numerical simulation (static working width and normalized working width) gave more accurate results when the improved material model was utilized.This paper presents a numerical study of a road barrier subjected to a bus crash test. The authors focus on the proper description of a barrier material model. Material model parameters are verified according to a simulated forming process. The solution uses modeling and simulation methods, as well as the finite elements method implemented with LS-DYNA software. The obtained results show that defining a proper road barrier model must consider the manufacturing process. Intensive plastic deformation leads to a significant increase in yield stress only in areas where the highest strain is observed during the forming process. The barrier model is divided into three zones, each of which have material properties characterized by different constants. The described construction, which uses homogenous material, is much more deformed and flatter than that of the improved model. Comparison with the experimental results shows that the new model better describes barrier deformation. In addition, deformation of the ba...

Nowadays polymers are commonly used in various applications, which make it difficult to avoid its usage even though it causes environmental problems. Natural fibers are best alternate to overcome the polymer based environmental issues. Natural fibers play an important role in developing high performing fully newline biodegradable green composites which will be a key material to solve environmental problems in future. In this paper deals the properties analysis of banana fiber is combined with epoxy resin in order to create a natural composite, which has special characteristics for aerospace applications. The objective of this paper is to investigate the characteristics of failure modes and strength of natural composite using experimental and numerical methods. The test specimen of natural composite has been fabricated as per ASTM standard, which undergoes tensile and compression tests using Tinius Olsen UTM in order to determine mechanical and physical properties. The reference model has been designed by CATIA, and then numerical simulation has been carried out by Ansys Workbench 16.2 for the given boundary conditions.Nowadays polymers are commonly used in various applications, which make it difficult to avoid its usage even though it causes environmental problems. Natural fibers are best alternate to overcome the polymer based environmental issues. Natural fibers play an important role in developing high performing fully newline biodegradable green composites which will be a key material to solve environmental problems in future. In this paper deals the properties analysis of banana fiber is combined with epoxy resin in order to create a natural composite, which has special characteristics for aerospace applications. The objective of this paper is to investigate the characteristics of failure modes and strength of natural composite using experimental and numerical methods. The test specimen of natural composite has been fabricated as per ASTM standard, which undergoes tensile and compression tests using Tinius Olsen UTM in order to determine mechanical and physical properties. The reference model has been designed by ...

In the study of depression, attempts to elucidate using mathematical models are not commonly performed. Therefore, in this paper, we introduce the construction of a new mathematical model for depression. We regard this study as a new method in the study on depression. Furthermore, in this paper, after constructing a mathematical model, numerical simulation is carried out, the time development of depression is visualized, and the purpose is also to capture the pathology.

Wake vortex safety analysis and control for unmanned aircraft systems (UAS) operating alongside commercial aircraft in the terminal zones are critical aspects in the integration of UAS into the National Airspace System (NAS), particularly in terminal airspace. We address an approach that integrates reduced-order models of wake generation, evolution, interaction and its control incorporating both theoretical and high-fidelity predictions. Our previous study [1] estimated UAS responses in terms of the roll control ratios (RCR) developed by the follower aircraft depending on their position and orientation relative to the wake shed by the leader aircraft, as well as the duration of the wake-UAS interaction. The current paper complements and expands the previous study to describe a predictive, robust feedback-loop flight control model that is applicable to various classes of UAVs in unsteady flight-path scenarios including control of wake response. The control design presented in this paper extends previous research results by first demonstrating asymptotic (zero steady-state error) altitude regulation control in the presence of unmodeled vertical wind gust disturbances. To address the practical considerations involved in small UAV applications with limited computational resources, the proposed control method is designed with a computationally simplistic structure, without the requirement of complex calculations or function approximators in the control loop. Proof of the theoretical result is summarized, and detailed numerical simulation results are provided, which demonstrate the capability of the proposed nonlinear control method to asymptotically reject wind gust disturbances and parameter variations in the state space model. Simulation comparisons with a standard linear control method are provided for completeness.

This paper presents modelling of both single and double-phase powder sintering processes at the macroscopic level. In particular, its constitutive formulation, numerical implementation and numerical tests are described. The macroscopic constitutive model is based on the assumption that the sintered material is a continuous medium. The parameters of the constitutive model for material under sintering are determined by simulation of sintering at the microscopic level using a micro-scale model. Numerical tests were carried out for a cylindrical specimen under hydrostatic and uniaxial pressure. Results of macroscopic analysis are compared against the microscopic model results. Moreover, numerical simulations are validated by comparison with experimental results. The simulations and preparation of the model are carried out by Abaqus FEA - a software for finite element analysis and computer-aided engineering. A mechanical model is defined by the user procedure “Vumat” which is developed by the first author in Fortran programming language. Modelling presented in the paper can be used to optimize and to better understand the process.This paper presents modelling of both single and double-phase powder sintering processes at the macroscopic level. In particular, its constitutive formulation, numerical implementation and numerical tests are described. The macroscopic constitutive model is based on the assumption that the sintered material is a continuous medium. The parameters of the constitutive model for material under sintering are determined by simulation of sintering at the microscopic level using a micro-scale model. Numerical tests were carried out for a cylindrical specimen under hydrostatic and uniaxial pressure. Results of macroscopic analysis are compared against the microscopic model results. Moreover, numerical simulations are validated by comparison with experimental results. The simulations and preparation of the model are carried out by Abaqus FEA - a software for finite element analysis and computer-aided engineering. A mechanical model is defined by the user procedure “Vumat” which is developed by the first author in F...

The paper presents the results of numerical simulation of the flow around a hypersonic inlet forebody to the entrance to the channel as well as the flow in a single boundary layer bleed channel. Simulation of the flow around the hypersonic inlet forebody has been carried out at Mach numbers M = 3, 4 6 and angles of attack of 4° and 6° using numerical solution of the Reynolds- averaged Navier-Stokes equations. Distributions of static pressure along the plane of symmetry and in the transverse direction are presented in the paper. Comparison of the numerical simulation results with experimental data has shown their satisfactory agreement. The parameters behind the bow shock wave obtained at the simulation of the flow around the inlet forebody have been used to specify the initial conditions for simulation of the flow through a boundary layer bleed hole.

Cold Roll Bonding (CRB) is recognized as an industrial technique in which the metal sheets are joined together in order to produce laminate metal composites. In this technique, a metallurgical bond resulting from severe plastic deformation is formed between the rolled metallic layers. The main objective of this paper is to analyse different factors which may affect the bond formation in rolling processes. To achieve this goal, first, an interface model is employed which describes both the bonding and debonding. In this model, the bond strength evolution between the metallic layers is calculated based on the film theory of bonding. On the other hand, the debonding process is modelled by means of a bilinear cohesive zone model. In the numerical section, different scenarios are taken into account to model the roll bonding process of metal sheets. The numerical simulation includes the modelling of joining during the roll bonding process followed by debonding in a Double Cantilever Beam (DCB) peeling test. In all simulations, the metallic layers are regarded as elastoplastic materials subjected to large plastic deformations. Finally, the effects of some important factors on the bond formation are numerically investigated.Cold Roll Bonding (CRB) is recognized as an industrial technique in which the metal sheets are joined together in order to produce laminate metal composites. In this technique, a metallurgical bond resulting from severe plastic deformation is formed between the rolled metallic layers. The main objective of this paper is to analyse different factors which may affect the bond formation in rolling processes. To achieve this goal, first, an interface model is employed which describes both the bonding and debonding. In this model, the bond strength evolution between the metallic layers is calculated based on the film theory of bonding. On the other hand, the debonding process is modelled by means of a bilinear cohesive zone model. In the numerical section, different scenarios are taken into account to model the roll bonding process of metal sheets. The numerical simulation includes the modelling of joining during the roll bonding process followed by debonding in a Double Cantilever Beam (DCB) peeling test. In ...

Seamless pipe elbows are important components in mechanical, plant and apparatus engineering. Typically, they are produced by the so-called ‘Hamburg process’. In this hot forming process, the initial pipes are subsequently pushed over an ox-horn-shaped bending mandrel. The geometric shape of the mandrel influences the diameter, bending radius and wall thickness distribution of the pipe elbow. This paper presents the numerical simulation model of the hot mandrel bending process created to ensure that the optimum mandrel geometry can be determined at an early stage. A fundamental analysis was conducted to determine the influence of significant parameters on the pipe elbow quality. The chosen methods and approach as well as the corresponding results are described in this paper.

Fuel efficiency requirements demand lightweight construction of vehicle body parts. The usage of advanced high strength steels permits a reduction of sheet thickness while still maintaining the overall strength required for crash safety. However, damage, internal defects (voids, inclusions, micro fractures), microstructural defects (varying grain size distribution, precipitates on grain boundaries, anisotropy) and surface defects (micro fractures, grooves) act as a concentration point for stress and consequently as an initiation point for failure both during deep drawing and in service. Considering damage evolution in the design of car body deep drawing processes allows for a further reduction in material usage and therefore body weight. Preliminary research has shown that a modification of load paths in forming processes can help mitigate the effects of damage on the material.This paper investigates the load paths in Nakajima tests of a DP800 dual phase steel to research damage in deep drawing processes. Investigation is done via a finite element model using experimentally validated material data for a DP800 dual phase steel. Numerical simulation allows for the investigation of load paths with respect to stress states, strain rates and temperature evolution, which cannot be easily observed in physical experiments. Stress triaxiality and the Lode parameter are used to describe the stress states. Their evolution during the Nakajima tests serves as an indicator for damage evolution. The large variety of sheet metal forming specific load paths in Nakajima tests allows a comprehensive evaluation of damage for deep drawing. The results of the numerical simulation conducted in this project and further physical experiments will later be used to calibrate a damage model for simulation of deep drawing processes.Fuel efficiency requirements demand lightweight construction of vehicle body parts. The usage of advanced high strength steels permits a reduction of sheet thickness while still maintaining the overall strength required for crash safety. However, damage, internal defects (voids, inclusions, micro fractures), microstructural defects (varying grain size distribution, precipitates on grain boundaries, anisotropy) and surface defects (micro fractures, grooves) act as a concentration point for stress and consequently as an initiation point for failure both during deep drawing and in service. Considering damage evolution in the design of car body deep drawing processes allows for a further reduction in material usage and therefore body weight. Preliminary research has shown that a modification of load paths in forming processes can help mitigate the effects of damage on the material.This paper investigates the load paths in Nakajima tests of a DP800 dual phase steel to research damage in deep drawing processes....

This paper presents a comparison of two criteria of strain localization in experimental research and numerical simulation of sheet metal forming. The first criterion is based on the analysis of the through-thickness thinning (through-thickness strain) and its first time derivative in the most strained zone. The limit strain in the second method is determined by the maximum of the strain acceleration. Experimental and numerical investigation have been carried out for the Nakajima test performed for different specimens of the DC04 grade steel sheet. The strain localization has been identified by analysis of experimental and numerical curves showing the evolution of strains and their derivatives in failure zones. The numerical and experimental limit strains calculated from both criteria have been compared with the experimental FLC evaluated according to the ISO 12004-2 norm. It has been shown that the first method predicts formability limits closer to the experimental FLC. The second criterion predicts values of strains higher than FLC determined according to ISO norm. These values are closer to the strains corresponding to the fracture limit. The results show that analysis of strain evolution allows us to determine strain localization in numerical simulation and experimental studies.This paper presents a comparison of two criteria of strain localization in experimental research and numerical simulation of sheet metal forming. The first criterion is based on the analysis of the through-thickness thinning (through-thickness strain) and its first time derivative in the most strained zone. The limit strain in the second method is determined by the maximum of the strain acceleration. Experimental and numerical investigation have been carried out for the Nakajima test performed for different specimens of the DC04 grade steel sheet. The strain localization has been identified by analysis of experimental and numerical curves showing the evolution of strains and their derivatives in failure zones. The numerical and experimental limit strains calculated from both criteria have been compared with the experimental FLC evaluated according to the ISO 12004-2 norm. It has been shown that the first method predicts formability limits closer to the experimental FLC. The second criterion predicts value...

The paper presents validation of numerical simulations of cavitating flows around different marine objects carried out at the Krylov State Research Centre (KSRC). Preliminary validation was done with reference to international test objects. The main part of the paper contains results of solving practical problems of ship propulsion design. The validation of numerical simulations by comparison with experimental data shows a good accuracy of the supercomputer technologies existing at Krylov State Research Centre for both hydrodynamic and cavitation characteristics prediction.

In designing sophisticated printed circuit boards, required evaluation of the product life cycle is relevant in terms of presumably applied load conditions during operation. The paper describes the durability evaluation method of printed circuit board components with contact output such as ball grid array (BGA) and pitch grid array (PGA) under thermal loads. Experiment data and numerical simulation results of soldered connections have been obtained. This method is demonstrated by a practical application example-evaluating of printed circuit board durability under cyclic thermal loads. The application of proposed method for printed circuit boards would make it possible to predict the service life of these designed products.In designing sophisticated printed circuit boards, required evaluation of the product life cycle is relevant in terms of presumably applied load conditions during operation. The paper describes the durability evaluation method of printed circuit board components with contact output such as ball grid array (BGA) and pitch grid array (PGA) under thermal loads. Experiment data and numerical simulation results of soldered connections have been obtained. This method is demonstrated by a practical application example-evaluating of printed circuit board durability under cyclic thermal loads. The application of proposed method for printed circuit boards would make it possible to predict the service life of these designed products.

In this paper we describe and validate a methodology for the numerical simulation of the fluid structure interaction in free surface flows. Specifically, this study concentrates on the vertical impact of a rigid body on the water surface, (i.e. on the hull slamming problem). The fluid flow is modeled through the volume of fluid methodology, and the structure dynamics is described by the Newton’s second law. An iterative algorithm guarantees the tight coupling between the fluid and solid solvers, allowing the simulations of lightweight (i.e. buoyant) structures.The methodology is validated comparing numerical results to experimental data on the free fall of different rigid wedges. The correspondence between numerical results and independent experimental findings from literature evidences the reliability and the accuracy of the proposed approach.In this paper we describe and validate a methodology for the numerical simulation of the fluid structure interaction in free surface flows. Specifically, this study concentrates on the vertical impact of a rigid body on the water surface, (i.e. on the hull slamming problem). The fluid flow is modeled through the volume of fluid methodology, and the structure dynamics is described by the Newton’s second law. An iterative algorithm guarantees the tight coupling between the fluid and solid solvers, allowing the simulations of lightweight (i.e. buoyant) structures.The methodology is validated comparing numerical results to experimental data on the free fall of different rigid wedges. The correspondence between numerical results and independent experimental findings from literature evidences the reliability and the accuracy of the proposed approach.

This paper presents experimental and theoretical study of the mechanical and strength properties of orthotropic composite materials. The anisotropy of a composite material is caused by its manufacturing method. Fiberglass composites based on epoxy resins (laminates) are investigated. The material is considered to be orthotropic, and the orthotropy axes coincide with the characteristic lines of fiber stacking. The aim is to develop a mathematical model of deformation and fracture of composite materials under quasi-static and dynamic loadings. The developed mathematical model is adapted to the Abaqus finite-element simulation software, which allows numerical simulation based on the original constitutive relations of an orthotropic medium taking into account the accumulation of damage. The paper compares experimental results and numerical simulation for flat specimens of an orthotropic composite material in the case of uniaxial deformation. Adequate results on the modeling of deformation and fracture of orth...

The research is focused on the simulation and experimental investigation of high-strain rate loading to study the mechanisms of plastic flow localization in metals (AlMg6) using a ballistic installation. Unique results of experiments are given in the paper. Numerical simulation using wide-range constitutive equations is done. The paper also shows the results of structural studies.

In this paper, we thought that the supply chain management of blood is impacted both by the loss of products and the seasonal fluctuation of supply source. From practically-existed problem, with the hypothesis of two kinds of substitutable blood at different loss rates, and the impact on ordering strategy from seasonal fluctuation being expressed as the probability of products arrival, we constructed two ordering models respectively considering two situations of distributed decision making and centralized decision making. Through the solution, numerical simulation, and comparison analysis for the models, we concluded that both centralized decision making and distributed decision making could well reach the status of supply chain coordination.

B-Pillars are specifically designed to absorb substantial energy with a minimum amount of deformation to limit its intrusion in the passenger compartment during an event of side impact. In this paper, the B-pillar has been developed using composite materials, with the main objective is to improve crashworthiness performance at a lesser weight, as a replacement for steel. The three-point bending test simulations of the composite B-pillar model were modelled, which applied various parameters of materials, number of ply and additional reinforcement. The composite B-pillar design parameter that scored the highest performance to weight ratio in the numerical simulation was then fabricated using vacuum bagging method. Subsequently, the B-pillar was tested under three-point bending experimental work. The force and central displacement results were compared to simulation data and a good agreement was obtained, where B-pillar made of carbon fibre reinforced polymer (CFRP) performed better than glass fibre reinforced polymer (GFRP). The simulation and experimental results indicated errors ranging between 6 and 15%. With the additional reinforcement at the critical area, the energy absorption of CFRP B-pillar was considerably improved by 18%. The weight of the fabricated composite B-pillar was 58% lighter compared to the original steel B-pillar. These results confirmed that the novel composite material holds a high strength, and has lightweight potential to substitute steel as car B-pillar material.The original version of this article supplied to AIP Publishing contained a typographical error in the title. The original title appeared as, “Finite element modelling and analysis of computer B-pillar,” whereas “computer” should have appeared as “composite.” This error has been addressed and corrected in the article republished on 28 February 2019.

Demand of high performance heat exchanger in industrial application is increasing since the depletion of energy resources such as in food processing plant, air-conditioning system and power plant. One of the ways of saving energy is by enhancing heat transfer performance, which in return will give a high performance heat exchanger. Existing enhancing techniques can be classified into three different categories which are active method, passive method and compound method. Spirally corrugated tube is one of the passive heat transfer enhancement method which involve surface extensions. The type of surface extension used in heat transfer performance will contribute to heat transfer coefficient and pressure drop, and directly affected the heat transfer performance. Traditionally, experimental studies were carried out to get the desired results but with the help of technology, numerical simulation is one of the promising alternatives in predicting reliable results for real application. For reliable numerical results, experimental studies are still necessary for the validation process and the verification process which comes before it is also mandatory. Thus, this paper focus on verification the numerical simulation of flow in a double-pipe heat exchanger with spirally corrugated internal tube. It was done for laminar flow with Reynolds number of 1000. Numerical simulation model using commercial CFD software were run with different mesh sizes to determine the grid independent solution and to choose which mesh is suitable to use for the whole simulation process. Minimizing and choosing the right mesh were done through Grid Convergence Index (GCI). Solutions of three different grids with their residuals convergence are also presented to fulfil the verification steps. The level of grid independence is evaluated using a form of Richardson extrapolation and the study shows that the finest grid solution has a GCI of less than 5%.

This paper presents a method to quantify the geometry of defects such as flat bottom holes (FBH) and notches in opaque materials by a pulse thermography (PT) experiment and a numerical model. The aim was to precisely describe PT experiments in reflection configuration with a simple and fast numerical model in order to use this model and a fit algorithm to quantify defects within the material. The algorithm minimizes the difference between the time sequence of a line shaped region of interest (ROI) on the surface (above the defect) from the PT experiment and the numerical data. Therefore, the experimental data can be reconstructed with the numerical model. In this way, the defect depth of a notch or FBH and its width or diameter was determined simultaneously. A laser was used for heating which was widened to a top hat spatial profile to ensure homogeneous illumination (rectangular impulse profile in time). The numerical simulation considers heating conditions and takes thermal losses due to convection and radiation into account. We quantified the geometry of FBH and notches in steel and polyvinyl chloride plasticized (PVC-U) materials with an accuracy of < 5 %.

In the paper, numerical simulation of shock wave propagation in the vicinity of a standalone prism and a prism with a cavity in front of it was carried out. The modeling was based on the solution of 3D Euler equations and Fluent software was used as a main computational tool. The algorithm for local dynamic mesh adaptation to high gradients of pressure was applied. The initial stage of the explosion of condensed explosive was described with the help of “Compressed balloon method”. The research allowed describing the characteristic stages of the blast in a semi-closed space, the structure of secondary shock waves and their interaction with obstacles. The numerical approach in Fluent based on combining inviscid gas dynamics methods and “Compressed balloon method” was compared with the method which had been used by the authors earlier with the help of AUTODYN and which is based on the use of the hydrodynamic model of a material to describe state of detonation products. For the problem of shock wave propagati...

ITB-ESDM-LIPI (Bandung Institute of Technology - Ministry of Energy and Mineral Resources – Indonesian Institute of Sciences) research collaboration program had successfully created a prototype of permanent magnetic axial turbine for very low head applications. The turbine was designed to produce 15 kW output power at 450 rpm and 4.5 m head. This paper aims to find the performance of axial hydraulic turbine using CFD method. In order to simulate the axial turbine, the experiment setup required pipes, valve, grille, orifice, and draft tube to fulfill the existing field requirements. The experiment test location was carried out at Cijedil hydropower facility which had a reservoir that potentially gives 35 m head. The numerical simulations of CFDs produced power, torque, and efficiency values in various number of turbine rotation and flow heads. Through the CFDs simulation, the power generated was 62,352.16 W, torque produced was 1,323.15 Nm and the maximum efficiency was 85.91 % on 4.5 m head and 450 rpm.

The thermal process modeling based on the operating data is effective to overcome the deficiency of mechanism modeling. In order to reduce the computational complexity of data-driven modeling, many sample selection algorithms have been used to decreasing the training dataset scale. However, traditional sampling selection algorithm may fail to cover full-scale working condition of thermal process when the dataset has large density deviations, and the sample selection criteria is often irrelevant to the modeling prediction. To overcome these issues, this paper proposes a wrapper full-scale sample selection algorithm for thermal process modeling, in which, samples will be sequentially added until there is no improvement in prediction, and sample selection criteria is the prediction evaluated by KNN regression model beforehand. It reveals that our algorithm not only cover full-scale working condition of thermal process, but also has certain superiority in model accuracy. Numerical simulation and real thermal application are conducted to validate the performance of the proposed algorithm.

Using the HyperXtrude module based on the Arbitrary Lagrangian-Eulerian (ALE) finite element method, the paper simulates the steady extrusion process of the asymmetric structure aluminum die successfully. A verification experiment is carried out to verify the simulation results. Having obtained and analyzed the stress-strain field, temperature field and extruded velocity of the metal, it confirms that the simulation prediction results and the experimental schemes are consistent. The scheme of the die correction and optimization are discussed at last. By adjusting the bearing length and core thickness, adopting the structure of feeder plate protection, short shunt bridge in the upper die and three-level bonding container in the lower die to control the metal flowing, the qualified aluminum profile can be obtained.

This paper deals with some examples of numerical modelling for ship’s dynamics problems and data comparison with corresponding experimental results. It was considered two kinds of simulation: self-propelled turning motion of crude carrier KVLCC2 and changing position of container carrier S 175 due to wave loadings. Mesh generation and calculation were made in STAR-CCM+ package. URANS equations were used as system of equations closed by k-w SST turbulence model. The vessel had several degrees of freedom, which depend on task. Based on the results of this research, the conclusion was made concerning the applicability of used numerical methods.

The paper considers numerical models of fracture processes of semi-circular asphalt mixture specimens subjected to three-point bending. Parameter calibration of the asphalt mixture constitutive models requires advanced, complex experimental test procedures. The highly non-homogeneous material is numerically modelled by a quasi-continuum model. The computational parameters are averaged data of the components, i.e. asphalt, aggregate and the air voids composing the material. The model directly captures random nature of material parameters and aggregate distribution in specimens. Initial results of the analysis are presented here.

A novel three degrees of freedom actuator is introduced and investigated in this paper. Actuator comprises a single cylinder type piezoelectric transducer with a disc shaped resonator glued on the top of the cylinder and a reflecting mirror. Ring shaped permanent magnet is used to clamp mirror on a steel hemisphere that is located in the center of the disc resonator. Actuator can realize up to three degrees of freedom i.e. to rotate the mirror about three axes independently. Harmonic vibrations of the resonator are excited by piezoelectric transducer and are employed to rotate the mirror. Bi-directional rotation of the mirror is obtained by switching excitation signals between different electrodes of the transducer. Both numerical simulation and physical prototype are used to verify the operating principle and results. Numerical investigation of the piezoelectric actuator was performed to investigate modal-frequency and harmonic response analysis of the piezoelectric actuator. Experimental study was used to measure electrical and mechanical output characteristics of the piezoelectric actuator. Results are analyzed and discussed.

International audience; The purpose of the work is to analyze the consistency of experimental data concerning classical turbulent combustion tests and their applicability for CFD programs validation. Efforts are directed to development and verification of a computationally efficient method for numerical simulation of turbulent combustion in a high-speed flow, based on RANS equations and taking into account turbulence-combustion interaction (TCI). Computations are fulfilled with zFlare module from application package EWT-TsAGI [1] which is based on in-house code ZEUS (TsAGI) [2] and intended to describe the flows of ideal compressible gases mixtures with variable heat capacities and nonequilibrium chemical reactions. Several kinetics models for H2 and hydrocarbon fuel combustion in air together with two-parameter turbulence models based on the Boussinesq hypothesis are implemented into the program. The paper describes some results of zFlare verification, as well as detailed analyses of experimental data. Five classical turbulent combustion experiments are regarded: Evans et al. experiments [3-4], Burrows & Kurkov [5], A.D. Cutler [6-7], Cheng et al. [8] and Moreau et al. backward-facing step combustor [9]. In addition, several approaches for TCI based on methods of Partially Stirred Reactor model (PaSR, [10]) have been studied and compared.

In the paper numerical simulation of the foamed metal structures using numerical homogenization algorithm is prescribed. From the beginning, numerical model of heterogeneous porous simplified structures of typical foamed metal, based on the FEM was built and material parameters (coefficients of elasticity matrix of the considered structure) were determined with use of numerical homogenization algorithm. During the work the different RVE models of structure were created and their properties were compared at different relative density, different numbers and the size and structure of the arrangement of voids. Finally, obtained results were used in modeling of typical elements made from foam metals structures - sandwich structure and profile filled with metal foam. Simulation were performed for different dimensions of cladding and core. Additionally, the test of influence material orientation (arrangement of voids in RVE element) on the maximum stresses and displacement during bending test was performed.

The paper presents the results of numerical simulation of plate impact loading for an aluminum alloy AMg6 to clarify thermodynamic and kinetic aspects of the transition from elastic to plastic fronts. This transition is connected with the metastability of out-of-equilibrium potential that reflects the type of criticality of solid with mesodefects—the structural-scaling transition. The modeling of mesodefects kinetics allowed one to establish the connection with mechanisms of defect induced structural relaxation responsible for the elastic precursor decay in metals. It was shown that transition from elastic to plastic fronts is realized due to the free energy release with kinetics related to metastability decomposition.

This paper adopts three different grids to conduct numerical simulation of flow field around an angle member by CFD. The two-dimensional incompressible Navier-Stokes equation is solved. The pressure velocity coupling adopts the SIMPLE algorithm and the pressure discretization adopts the standard algorithm. Both the momentum equation and turbulence model adopt the second-order windward scheme, and the time term adopts the second-order implicit scheme. The aerodynamic coefficients of angle member and the flow field are obtained by different grids, and through comparison, it is found that the grid mode has a very small impact on the CFD results, and the differences between different grid modes can be ignored. In respect of CFD simulation of flow field around angle member in transmission tower, it is recommended to adopt the partitioned structured grids and the partitioned mixed grids in order to enhance the simulation ability of the grid under multiple working conditions. If the angle member is irregularly shaped, the partitioned mixed grids are preferred.

High speed velocity effects in production technology provide a broad range of technological and economic advantages [1, 2]. However, exploiting them necessitates the knowledge of strain rate dependent material behavior in process modelling. In general, high speed material data characterization features several difficulties and requires sophisticated approaches in order to provide reliable material data. This paper proposes two innovative concepts with electromagnetic and pneumatic drive and an approach for material characterization in terms of strain rate dependent flow curves and parameters of failure or damage models. The test setups have been designed for investigations of strain rates up to 105 s-1. In principle, knowledge about the temporary courses and local distributions of stress and strain in the specimen is essential for identifying material characteristics, but short process times, fast changes of the measurement values, small specimen size and frequently limited accessibility of the specimen during the test hinder directly measuring these parameters at high-velocity testing. Therefore, auxiliary test parameters, which are easier to measure, are recorded and used as input data for an inverse numerical simulation that provides the desired material characteristics, e.g. the Johnson-Cook parameters, as a result. These parameters are a force equivalent strain signal on a measurement body and the displacement of the upper specimen edge.

In this paper, the point cloud data of FAW-VOLKSWAGEN car body shape is obtained by three coordinate measuring instrument and laser scanning method. The accurate three dimensional model of the car is obtained using CATIA software reverse modelling technology. The car body is gridded, the calculation field and boundary condition type of the car flow field are determined, and the numerical simulation is carried out in Hyper Mesh software. The pressure cloud diagram, velocity vector diagram, air resistance coefficient and lift coefficient of the car are obtained. The calculation results reflect the aerodynamic characteristics of the car’s external flow field. The motion of the separation flow on the surface of the vehicle body is well simulated, and the area where the vortex motion is relatively intense has been determined. The results provide a theoretical basis for improving and optimizing the body shape.

The paper is devoted to the description of a complex approach to the numerical modeling of secondary thermodynamic effects generated in heterogeneous porous-type materials under the influence of ionizing radiation. This approach is divided into several stages including the construction of a geometrical model of a porous material, simulation of interaction with radiation and further modeling of thermodynamic effects. The creation of a geometric model occurs in accordance with a number of requirements put forward by the general approach. To simulate pores distribution, Lubachevsky–Stillinger spheres packing algorithm is used. The approach also includes the algorithm for construction of system of detectors for statistical estimation of the radiation energy deposit in an irradiated object. The distribution of energy release in an irradiated sample obtained at the second stage of numerical simulation is used in hydro- and thermodynamic models to estimate the secondary thermodynamic effects. Thermodynamic behav...

Additive-manufacturing technologies have been gaining tremendously in popularity for some years in the production of single-part series with complex, close-to-final-contour geometries and the processing of special or hybrid materials. In principle, the processes can be subdivided into wire-based and powder-based processes in accordance with the Association of German Engineers (VDI) Guideline 3405. A further subdivision is made with respect to the smelting technology. In all of the processes, the base material is applied in layers at the points where it is needed in accordance with the final contour.The process that was investigated was wire-based, multi-pass welding by means of gas–metal arc welding. This was accomplished in the present study by determining the material parameters (thermo-mechanical and thermo-physical characteristics) of the welding filler G3Si1 (material number: 1.5125) that were necessary for the numerical simulation and implementing them in a commercial FE program (MSC Marc Mentat). The focus of this paper was on simulation and validation with respect to geometry and microstructural development in the welding passes. The resulting minimal deviation between reality and simulation was a result of the measurement inertia of the thermocouples. In general, however, the FE model can be used to make a very good predetermination of the cooling behaviour, which affects the microstructural development and thus the mechanical properties of the joining zone, as well as the geometric design of the component (distortion, etc.).

A Multi-cusp DC arc-discharge hydrogen negative ion (H−) source has been developed for proton cyclotron applications. The purpose of this study is to understand the dependency of the H− surface production on the operation parameters and optimize the H− surface production in the source. In this paper, spatial distribution of H atom production due to the H2 dissociation and H atom flux onto the plasma grid (PG), both of which play a key role for the H- surface production, have been calculated by the KEIO-MARC code and the neutral (H2, H) transport code. These simulation results provide useful information for optimization of the H− surface production in the source.

With oil many infillings, thin and poor reservoir exploitation changes gradually to low permeability, thin and poor reservoir development characteristics of multiple layers thickness, low permeability, in the actual development process, the General Department of oil layers of encryption perforation long thin and poor mining, interlayer contradiction more prominent, by conventional layered water injection that can alleviate the contradiction between layers to a certain extent, by the injection interval and other factors can not fundamentally solve the problem, leading to the potential well area key strata or layers is difficult to determine, the layering test and slicing technology is difficult to adapt to the need of tap water control block. This paper through numerical simulation using the conceptual model and the actual block, it has a great influence on the low permeability reservoir of different stratified water permeability combination of permeability technology and application limits, profit and loss balance principle, low oil prices on the lower series of subdivision technical and economic limit, so the reservoir subdivision reorganization, narrow wells mining, reduce the interference between layers, from the maximum fundamental improvement of layered water injection efficiency. At the same time, in order to meet the needs of reservoir subdivision adjustment, subdividing distance with water, a small interlayer wells subdivision technology for further research in the pickup, solved using two ordinary bridge eccentric water regulator with injection of two layers, by throwing exercise distance limit card from the larger problem, the water distribution card size from 7.0m to 1.0m, and the testing efficiency is improved, and provide technical support for further subdivision water injection wells.

The paper focus on the numerical investigation of a pump impeller combined with an axial rotor for a double-flux pump storage. The axial rotor is investigated at variable speed between 2000 and 3000 rpm with a step size of 100 rpm, while the speed of the pump impeller is maintained constant at 2500 rpm. An improved cavitational behaviour is obtained for solution with axial rotor when the speed varies.

The paper presents numerical simulation data on the abutment pressure redistribution in rock mass during face advance, including isolines of maximum shear stress and pressure epures. The stress state of rock in the vicinity of a breakage heading is calculated by the finite element method using a 2D nonlinear model of a structurally heterogeneous medium with regard to plasticity and internal self-balancing stress. The thus calculated stress field is used as input data for 3D discrete element modeling of the process. The study shows that the abutment pressure increases as the roof span extends and that the distance between the face breast and the peak point of this pressure depends on the elastoplastic properties and internal self-balancing stress of a rock medium.

This paper represents a classical numerical scheme which enables us to solve non-linear hyperbolic equations numerically. For that purpose, the Lax-Friedrichs and Lax-Wendroff schemes are used to solve the Burger’s equation in order to improve an understanding of the numerical diffusion and oscillations that can be present when using such schemes. By solving the Burger’s equation based on both schemes mentioned, a verification of the numerical features such as accuracy, convergence rate and efficiency of the schemes for given initial and boundary values was made. For both of the schemes simulated, Lax-Wendroff scheme gave more accurate solution for solving a Burger’s equation since it has two degree precision along time compare to the Lax-Friedrichs scheme. However, implementing the Lax-Wendroff scheme needs to solve derivatives up to fourth order, hence need more computational time compare to the Lax-Friedrichs scheme. At the same time, numerical simulation with a different time steps showed a better res...

The paper describes the linear density of the heat flow using dimensional analysis in the case of underground, pre-insulated piping. The methodology makes it possible to determine the heat loss based on a simple criterial relationship. Heat losses in the piping system were also calculated using numerical simulation. The difference between the experimentally detected losses and the values obtained from the model is −3.6% to 6.4%. The results of the numerical simulation at an ambient temperature of 25°C differ from the experiment by −1.7%. At an ambient temperature of −10°C the difference is −4.0%.

The present paper studies the influence of the shape of projectile (damage agent) on its penetration capability. Steel projectiles of different shape have been considered as damage agents: sphere, regular tetrahedron, cube, cylinder and plate. The weight of projectiles has been kept the same. Antitank grenade has been used as a target. The study has been conducted by means of numerical simulation using finite element analysis. The simulation is three-dimensional. Behavior of materials has been described by elasto-plastic model taking into consideration the fracture and fragmentation of interacting bodies. The speed of interaction has been considered within the range of 800 to 2000 m/s. Research results demonstrated significant influence of the projectile shape on its penetration capability. Projectile in the shape of elongated cylinder has shown better penetration capability. Considering the weight of damage agents (except for sphere and plate) their maximum penetration capability has been reached at the ...

Selective Laser Melting (SLM) process belonging to the family of the Additive Manufacturing (AM) technologies, enable to build parts layer by layer, from metallic powder and a CAD model. Physical phenomena that occur in the process have the same issues as conventional welding. Thermal gradients generate significant residual stresses and distortions in the parts. Moreover, the large and complex parts to manufacturing, accentuate the undesirable effects. Therefore, it is essential for manufacturers to offer a better understanding of the process and to ensure production reliability of parts with high added value. This paper focuses on the simulation of manufacturing turbine by SLM process in order to calculate residual stresses and distortions. Numerical results will be presented.

The present paper deals with the numerical simulation of fluid flow with heated obstacle in a channel. A three dimensional finite element method for channel flow with heated obstacle is developed and a tool of computational fluid dynamics (CFD) is employed to assist the process. This study presents the detail effects with respect to the variations in the obstacle’s height, width, spacing, and number. The studied results depict the trends due to variable obstacle thermal conductivity, fluid flow rate, pressure and heating method. The periodic behaviour of the velocity components and temperature distributions are also explicitly demonstrated.

The implementation of surface-based Monte Carlo simulation technique for oxygen saturation (SaO2) calibration curve estimation is demonstrated in this paper. Generally, the calibration curve is estimated either from the empirical study using animals as the subject of experiment or is derived from mathematical equations. However, the determination of calibration curve using animal is time consuming and requires expertise to conduct the experiment. Alternatively, an optical simulation technique has been used widely in the biomedical optics field due to its capability to exhibit the real tissue behavior. The mathematical relationship between optical density (OD) and optical density ratios (ODR) associated with SaO2 during systole and diastole is used as the basis of obtaining the theoretical calibration curve. The optical properties correspond to systolic and diastolic behaviors were applied to the tissue model to mimic the optical properties of the tissues. Based on the absorbed ray flux at detectors, the OD and ODR were successfully calculated. The simulation results of optical density ratio occurred at every 20 % interval of SaO2 is presented with maximum error of 2.17 % when comparing it with previous numerical simulation technique (MC model). The findings reveal the potential of the proposed method to be used for extended calibration curve study using other wavelength pair.

Low frequency guided wave based inspection is an extensively used method for asset management with the advantage of wide area coverage from a single location at the cost of spatial resolution. With the advent of high frequency guided waves, short range inspections with high spatial resolution for monitoring corrosion under pipe supports and tank annular plates has gained widespread interest and acceptance. One of the major challenges in the application of high frequency guided waves in a short range inspection is to attain the desired modal displacements with respect to the application. In this paper, an investigation on the generation and formation of fundamental S0 mode is carried out through numerical simulation and experiments to establish a prenatal zone for guided waves. The effect of frequency, thickness of the plate and frequency-thickness (f*d) is studied. The investigation reveals the existence of a rudimentary form with similar modal features to the fully developed mode. This study helps in the...

The need for a new and improved fisheries port has significantly increased in the Bireuen District of Aceh, particularly in Peudada due to several factors presented in this paper. During this time the fishing port used by the communities located in the river channel makes it difficult for the fishermen to get into the port area due to the shallowness of the mouth of the estuary. Port master plan study is required to examine several possible locations for the proposed port. In planning the hydro-oceanographic aspects of the port is an essential requirement to determine the layout of a port. Several factors that need to be reviewed relating to the layout of the ports include sedimentation, waves, and currents. These factors affect the movement of the ship, tranquility waves in the port basin, and for the maintenance dredging of the harbor due to sedimentation. This study is aimed at estimating the best layout of the port basin between two scenarios due to the sedimentation process, waves propagation, and cu...

Impact sensitivity of solid high explosives, an important index in evaluating the safety and performance of explosives, is an important concern in handling, storage, and shipping procedures. It is a great threat for either bare dynamite or shell charge when subjected to low velocity impact involved in traffic accidents or charge piece drops. The Steven test is an effective tool to study the relative sensitivity of various explosives. In this paper, we built the numerical simulation method involving mechanical, thermo and chemical properties of Steven test based on the thermo-mechanical coupled material model. In the model, the stress-strain relationship is described by dynamic plasticity model, the thermal effect of the explosive induced by impact is depicted by isotropic thermal material model, the chemical reaction of explosives is described by Arrhenius reaction rate law, and the effects of heating and melting on mechanical properties and thermal properties of materials are also taken into account. Spe...

Nowadays, the incremental flowforming process is widely explored because of the usage of complex tubular products is increasing due to the light-weighting trend and the use of expensive materials. The enhanced mechanical properties of finished parts combined with the process efficiency in terms of raw material and energy consumption are the key factors for its competitiveness and sustainability, which is consistent with EU industry policy. As a promising technology, additional steps for extending the existing flowforming limits in the production of tubular products are required. The objective of the present research is to further expand the current state of the art regarding limitations on tube thickness and diameter, exploring the feasibility to flowform complex geometries as tubes of elevated thickness of up to 60 mm. In this study, the analysis of the backward flowforming process of 7075 aluminum tubular preform is carried out to define the optimum process parameters, machine requirements and tooling geometry as demonstration case. Numerical simulation studies on flowforming of thin walled tubular components have been considered to increase the knowledge of the technology. The calculation of the rotational movement of the mesh preform, the high ratio thickness/length and the thermomechanical condition increase significantly the computation time of the numerical simulation model. This means that efficient and reliable tools able to predict the forming loads and the quality of flowformed thick tubes are not available. This paper aims to overcome this situation by developing a simulation methodology based on FEM simulation code including new strategies. Material characterization has also been performed through tensile test to able to design the process. Finally, to check the reliability of the model, flowforming tests at industrial environment have been developed.

Residual stresses induced in the component by previous thermal/mechanical processes are compressive or tensile stresses having a zero resultant. In particular, they arise as consequence of thermo-mechanical processes (e.g. ring-rolling process), casting and heat treatments. When machining stressed components, volume removal leads to a re-arrangement of residual stresses, which inevitably causes distortions in the workpiece. If distortions are excessive, they can lead to a large number of scrap parts. This paper describes the development of a numerical procedure for the analysis of the distortions on a waspaloy turbine case, obtained by ring rolling process. A 3D model of ring rolling process has been set in the commercial software DEFORM 3D. Three different ring rolling strategies have been analyzed, in order to find the combination of process parameters which allows to obtain the best component in terms of geometrical precision. Then, the heat treatments (air cooling, solubilization, stabilization and aging) have been simulated to predict the bulk residual stresses distributions. Finally, the numerical distortions induced by machining have been simulated considering the material removal in some machining operations.

In this paper we present a splitting algorithm for a numerical simulation of Li-ion battery electrochemical processes. Liion battery consists of three domains: anode, cathode and electrolyte. Mathematical model of electrochemical processes is described on a microscopic scale, and contains nonlinear equations for concentration and potential in each domain. On the interface of electrodes and electrolyte there are the Lithium ions intercalation and deintercalation processes, which are described by Butler-Volmer nonlinear equation. To approximate in spatial coordinates we use finite element methods with discontinues Galerkin elements. To simplify numerical simulations we develop the splitting algorithm, which split the original problem into three independent subproblems. We investigate the numerical convergence of the algorithm on 2D model problem.