For an improvement of the multiphase flow simulations on/inside complex geometry, the conservative Allen-Cahn equation is coupled with the pressure evolution equation, and they are solved by the lattice Boltzmann method (LBM). Furthermore, the cubic boundary condition is employed at the solid-fluid boundary in order to reproduce the given contact angle in higher order. The present method is evaluated for a sessile droplet on a flat plate. Since the diffuse interface method by LBM tends to leak the phase volume from the interfaces, we imposed on the phase volume conservation and evaluated with different given contact angles. The contact angle representation is also investigated. It is confirmed that the given contact angle agrees well with the resulted contact angle from lyophilic to lyophobic surface wettability. The volume leakage can be suppressed up to 2% which is not from the liquid-solid interface but from gas-liquid interface.

Structures including dynamic movements such as storage and deployment are attracting attention in fields such as architecture and space. Buckling is generally known as cause of crush or an unstable phenomenon that makes it difficult to predict the shape after buckling, but the out-of-plane buckling such as slack generated in a thin film relieves stress concentration at the time of deployment and enable smoothly deployment. It also has advantages such as making it possible to construct a bi-stable structure. In this research, the authors apply a mathematical model to detect buckling, quantify the instability, visualization, response analysis after buckling, for structures with large deformation from moment to moment like storage and deployment. The authors developed the analysis code and applied some models of simple truss arch and a model of deployment of a flexible membrane. The detection, the quantification, and the visualization of the buckling was confirmed by the analyses.

Boiling in quenching process is an important and significant phenomenon, due to the variations of cooling rate and finally the deformation of the product, which has been paid much attention in the past few decades. However, it is still difficult to conduct accurate measurements, because of the small spatial scales and rapid time constants. Authors proposed phase-field approach applied for non-equilibrium gas-liquid interface and derive a mathematical equivalence to a viscous solution of level-set equation, which has been often applied to an improvement of VOF method. This paper applies a solver “interThermalPhaseChangeFoam” in OpenFOAM with such a improved VOF method to a simplified model for quenching of over-heated wall. A typical heat transfer variation in over-heated wall boiling are captured, where the vapor film, nucleate boiling and convection stages are reproduced from the results of time evolution of heat flux.

In this paper, a simultaneous optimization method for shape and topology design of shell structures is presented. The compliance is used as the objective functional, and minimized under the volume constraint. The free-form optimization method for shells and SIMP method are employed for shape and topology design. Shape and homogenized-density variations are the design variables, and simultaneously determined in one iteration. This design problem is formulated as distributed-parameter optimization problem, and the shape and density gradient functions are derived based on the variational method, the material derivative method and the adjoint variable method, which are respectively applied to the H¹ gradient methods for vector and scalar design variables to determine the optimal shape and topology of shell structures. With the proposed method, the optimal shape and topology is obtained without the shape parameterization while eliminating the numerical instability problems such as a jagged shape, a checkerboarded and a greyscaled topology. A numerical example shows the validity of the proposed method.

To explain and engineer intrinsic point defect behavior in large-diameter single crystal Si grown using the Czochralski (CZ) method, a unified model valid for all pulling processes, crystal resistivities, and electrically inactive impurity concentrations that couples the effects of thermal stress, dopants, and interstitial oxygen (O_i) atoms is needed. We determined the thermal equilibrium concentration of intrinsic point defects (vacancy V and self-interstitial Si I) in CZ-Si crystal as functions of thermal stresses, type and concentration of dopant, and the concentration of O_i atoms. Global heat transfer during crystal growth in a puller was simulated using STR Group's CGSim software package. A visual distribution of V and I concentrations inside a growing doped and thermally stressed Si ingot is very useful for improving the quality of large-diameter CZ-Si crystals.

Power electronics apparatuses control high voltage / large current by power semiconductor chips such as IGBTs (Insulated Gate Bipolar Transistors) and diodes. When semiconductor chips fail during operation and short-circuits occur, a large burst pressure is generated by the energy stored in the circuit. However, since the quantitative evaluation of the semiconductor chip burst phenomenon is not sufficient, the protective structure around the semiconductor chips is designed by trial and error. This paper reports the estimation of the pressure generated when a semiconductor chip bursts due to the large current by constructing the structural analysis model based on experimental results.

In sheet forming, the blank holder force (BHF) have a direct influence on product quality. A high BHF leads to tearing, whereas a low one results in wrinkling. For successful sheet forming, the BHF should be adjusted. Recently, the variable BHF (VBHF) that the BHF varies through stroke is recognized as one of the advanced sheet forming technologies. On the other hand, slide velocity (SV) that controls the die velocity is rarely discussed in the literature, and the SV should also be taken into account for the successful sheet forming. The VBHF trajectory and SV are unknown in advance, and the trial and error method is widely used. This study proposes a method to determine the optimal VBHF and SV for high product quality and high productivity. Therefore, multi-objective optimization is performed. Numerical simulation in sheet forming is so intensive that a sequential approximate optimization using radial basis function network is adopted to determine the optimal solution. Based on the numerical result, the experiment is carried out.

We present fully thermo-mechanical coupled two-scale analysis for general dissipative solids. We firstly define thermo-mechanical coupled energy functional by that thermo-mechanical coupled incremental variational framework is combined with Hu-Washizu type formulation reflected in hyperelastic constitutive law and Fourier-type heat conduction law. After that, we apply the generalized convergence theory to it, which let us create the two-scale thermo-mechanical coupled problem that rate-dimensional state variables are solved. The applicability of our proposed method is verified by performing numerical material testing and FE² type multiscale analysis.

We numerically investigate the rheology of a suspension of red blood cells (RBCs) in a wall-bounded shear flow. The behavior of RBCs, modeled as a biconcave capsule whose membrane follows the Skalak's constitutive law, is simulated for volume fractions of RBCs up to φ = 0.41 and different Capillary numbers (Ca). Our numerical results show that, an RBC subjected to low Ca tends to orient to the shear plane and exhibits the rolling motion, a stable mode with higher intrinsic viscosity than the tumbling motion. As Ca increases, the stable mode shifts from the rolling motion to the swinging motion. Hydrodynamic interaction (higher volume fraction) also allows RBCs to exhibit the tumbling or swinging motions resulting in a drop of the intrinsic viscosity for dilute and semi-dilute suspensions. Because of this mode change, conventional ways of modeling the relative viscosity as a polynomial function of φ cannot be simply applied in suspensions of RBCs at low volume fractions. The relative viscosity for high volume fractions, however, can be well described as a function of an effective volume fraction which is defined as an equivalent spherical volume fraction based on the semi-middle axis of the deformed RBC.

Lattice structure can be used as a scaffold for damaged bone, whose mechanical properties are the matter of concern in its design. For such a medical use, the quality assurance is very important. However, the variability in mechanical properties or imperfections can be seen in the additively manufactured products. Therefore, in the design stage before manufacturing, CAE tool that is capable of stochastic simulation considering the uncertainty, variability or imperfections is promising. For a simple lattice structure that has periodical arrangement of a unit architecture, this paper presents the computational framework using the first-order perturbation based stochastic homogenization (FPSH) method.

We present identification analysis of order of singularity around singular point of bonded structure using displacement values. The finite element and the adjoint variable methods are employed for the identification of the order of singularity. In addition, the Akin's singular element is introduced in the deformation analysis of the bonded structure model. The steepest descent method is applied to identify the order of singularity.

Solution methods of capacitively coupled plasmas (CCPs) have been facing a monumental challenge because the solution for the overwhelming number of radio frequency (RF) cycles is in demand before the plasma evolves to a time periodic steady state. It is known that the conventional solution methods require an extremely long calculation time, hence these methods would be limited in industrial applications that need a fast development period. In this paper, a new numerical simulation method for CCPs by COMSOL Multiphysics^® is presented. The solution of CCPs in the time domain is converted to a boundary value problem in the additional dimension space to the computational space dimension of the CCP reactor. The fast solutions of the axisymmetric two-dimensional CCPs in Ar and Ar/N₂ are performed and the computational efficiency is examined.

Medical device such as implant is one of the promising applications of additive manufacturing by selective laser melting of titanium or titanium alloy powder. The additive manufacturing and the support by CAE for dental prosthesis are studied in this paper, highlighting on the quality assurance and the robust design because variability exists due to the manufacturing process. The stiffness of the dental prosthesis is one of the important design factors, which is requested to be within certain range. Therefore, the maximum stiffness and the minimum one are both predicted in addition to the averaged or expected value. Starting from the static tensile test using dumbbell-shaped specimens to build up the elasto-plastic material model considering variability, this paper presents the micro-CT image-based FEA of two types of prostheses. The difference in the positioning on the powder bed during additive manufacturing led to approximately 15% difference for Young’s modulus and 9% difference for yield stress and ultimate stress of the titanium alloy, Ti-6Al-4V, whose influences were discussed.

Peridigm using a particle model can be cited as one analysis method which is good at dealing with large deformation and accompanying destruction phenomena. However, Peridigm has not sufficiently studied static phenomena such as deformation of members due to load like FEM. For this reason, we conduct quasi static analysis for elastic region and elastic-plastic region with Peridigm and compare it with the results of analysis with FEM to examine the significance of structural analysis using particle model.From these results, it was proved that it is possible to reproduce mechanical phenomena like a continuum also in a Preidigm.

Improvement of rolling resistance of car tires has recently been required. The rolling resistance of pneumatic tires is mainly attributed to energy dissipation related to viscoelastic behavior of rubber materials. In order to calculate the rolling resistance by numerical simulations, such as finite element method, it is important to use the material model which has a capability to precisely capture the viscoelastic behavior of rubbers. A new nonlinear viscoelastic model which can reproduce the complicated viscoelastic behavior depending on deformation rate and amount of deformation has been developed by our research group. This study implemented the developed model into a commercial finite element code “Abaqus” and performed rolling simulations of tires. The developed model showed a better prediction of the rolling resistance than the conventional viscoelastic model. And it was revealed that the rolling resistance predicted by the developed model had an excellent correlation with experimental results.

Simple and efficient mechanical models for the interaction between a Shinkansen train and railway structure including derailment during an earthquake are given. A computational method to solve the dynamic interaction including derailment during an earthquake is described. Based on the computational method a simulation program has been developed. Numerical examples are demonstrated.

The multi-phase-field (MPF) method is widely employed in recent years as a prominent tool for simulating polycrystalline grain growth, since it enables us to handle complicated grain boundary migration without explicitly tracking the positions of grain boundaries. The MPF models are classified into two types according to the constraints for phase-field variables: one is the MPF model in a narrow sense; and the other is the continuum-field (CF) model. Both of these models are reported to allow for accurately simulating grain growth under uniform grain boundary energy and mobility. However, for the cases where the grain boundary properties exhibit large differences, the accuracies of the models are not yet examined in detail. In this study, using the MPF and CF models, systematic grain growth simulations with nonuniform grain boundary properties are performed. Through the detailed investigation on the accuracy of the simulated results, the applicable range of the models are revealed.

Oil-filled power transformers play an important role in the modern network system. Stability of power supply can be achieved by early detection of power transformer fault and continuous monitoring of equipment status. However conventional diagnosis approaches for power transformers depend upon the experience and high technology of human experts. Therefore in this paper, artificial intelligence techniques are applied to the fault intelligent diagnosis for power transformers. Furthermore the predicted results of fault diagnosis are verified by using actual database.

Accelerated gradient methods have recently received considerable attention for solving diverse large-scale convex optimization problems. In such methods, fast local convergence to an optimal solution is realized, while cheap computational cost per iteration of a gradient method is retained. This paper presents an accelerated Uzawa method for solving frictionless contact problems in linear elasticity. An adaptive restart scheme of the acceleration is adopted for achieving monotonic decrease of the dual objective value. Preliminary numerical experiments suggest that the convergence of the Uzawa method drastically is speeded up by the proposed method.

In this study, a new fatigue crack propagation analysis method is proposed using the smoothed particle hydrodynamics (SPH). First, a crack is simply modeled as an aggregate of particle voids and the crack tip line is given a feature of changing its shape naturally like a chain. Next, a crack propagation algorithm that uses the SPH when solving the equation and updating the crack tip is constructed. Finally, several numerical solutions are given to confirm the utility and the validity of the proposed method. In case of a crack propagation problem around a hole, the crack separation and merging process is computed successfully, and, in another crack propagation study around a slit, the numerical result shows almost the same time dependent crack shape history as an experimental result.

We proposed a bi-stable vibration system composed of elastic springs and mass blocks supporting from an oblique direction. From experimental results and numerical analysis results, it was confirmed that stochastic resonance was reliably generated using the proposed bi-stable vibration system of this study, and amplitude amplification effect about several times higher than normal vibration response was obtained. Compared to the conventional bi-stable vibration model, the larger amplitude is obtained, the degree of freedom directions other than the movement direction of the mass block are guided, and it is shown that the influence of accidental impact load from outside is small. And investigated important design factors of bi-stable vibration system proposed by this research and gained useful knowledge for future research.

In order to improve the occurrence of the Euler buckling phenomenon which laterally bends when an impact load is applied to the elongated thin column structure in the axial direction and thereby greatly deteriorates the collision energy absorption performance of the structure, We proposed an inverted torsion type collision energy absorbing structure, developed experimental machining equipment, trial experiments, and examined in detail.

In this paper, the method for introduction of cohesive zone models to finite element models considering symmetric conditions was investigated. In order to fulfill the conditions, constrained conditions for nodes of interface elements, fracture toughness, and penalty stiffness should be appropriately given. Constrained conditions are determined so that only mode I deformation is occurred. In addition, fracture toughness and penalty stiffness are set to half and double of actual values, respectively. The method was verified through damage propagation analyses for two-kinds of models including 3-point bending beam and DCB test specimen.

In the vehicle platoon, vehicles move in the small distance. It can improve the traffic capacity of the traffic road network. For the safety traffic flow in the vehicle platoon, the vehicles are controlled with electric and mechanical systems. This study focuses on the simulation where vehicles in the platoon overtake the other vehicle. The vehicle velocity is controlled with the vehicle following model such as Chandler model, extended Chandler model and Asahina model. The model is confirmed in the simulation of three-vehicle platoon overtaking a vehicles. The results show that the extended Chandler model can control the vehicle platoon stably.

Grammatical Evolution (GE), which is one of the evolutionary computations, is designed to find the functions or program satisfying the design objective. The candidate solutions are defined as the string of the binary or decimal numbers. The population of the candidate solutions are evolved in order to find the better solution. The population size is one of the important control parameters in Grammatical Evolution. The aim of this study is to discuss the effect of the population size in symbolic regression problem. At the different population size; 1 and 200, the simulation is performed. The results show that the better solution can be found in case of 1 than 200 for the population size.

The incompressible smoothed particle hydrodynamics (ISPH) method is a kind of numerical methods for the incompressible Navier–Stokes equations. Unique solvability and stability are analyzed for implicit and semi-implicit schemes in the ISPH method. Sufficient conditions for unique solvability and stability are introduced: a connectivity condition, a semi-regularity condition, and a time step condition. The unique solvability of both the implicit and semi-implicit schemes in two- and three-dimensional spaces is obtained with the connectivity condition. The stability of the implicit scheme in two-dimensional space is obtained with the connectivity and regularity conditions.

A method to remove the effect of element size and distance from crack tip on inelastic strain energy density range near the crack tip was proposed, and the method was applied to evaluation for fatigue crack propagation of Sn-5Sb/Cu joint. The fatigue crack propagation rate obeyed a Paris type fatigue crack propagation law using the inelastic strain energy density. The continuous dynamic recrystallization occurred in the low strain energy region and the fatigue crack propagated at grain boundaries formed by the recrystallization. In the high strain energy region, the fatigue crack developed by cleavage, which resulted in large exponent of the fatigue crack propagation law.

The present paper describes a new high-precision finite element method with deep learning. This method makes it possible to get high-precision analysis results from those obtained only with a coarse mesh, indicating a kind of break-through for the inevitable limit of the finite element method. It also uses a posteriori error analysis such as Zienkiewicz-Zhu (ZZ) method. The proposed method consists of three phases. In the first phase, a lot of data set for many analysis settings are collected, each of which includes results and a posteriori error analyses with a coarse mesh, and results with a very fine mesh. Then in the second phase, neural networks are trained to estimate the results with a fine mesh from the results and errors with a coarse mesh. And finally, in the third phase, the trained neural networks are utilized to estimate high-precision analysis results from the results of a new coarse mesh. Basic performance of the proposed method is successfully tested through simple 2D stress analysis.

In this paper, we proposed a novel particle method for free-surface flow in the presence of surface tension forces. The proposed method uses moving surface mesh that defines interface between gas and liquid; inner volume represents the liquid phase and outer the gas. Since gas-liquid interface is explicitly described and accurately calculated, surface tension force can be evaluated with high accuracy. Internal liquid flow is simulated using a particle method, in which spatial derivatives are discretized using the arbitrary high order accurate LSMPS scheme. Boundary conditions are imposed using copy particles and analytical volume integrations. As numerical examples, simulations of two-dimensional droplet oscillations, axisymmetric liquid bridge deformation, and hanging droplet are demonstrated.

We tested Artificial Neural Networks (ANNs) to predict a fully-developed turbulent channel flow of a viscoelastic fluid in preparation for elucidating flow phenomenon and solving the difficulty in DNS (Direct Numerical Simulation) due to numerical instability of the viscoelastic fluid. Two kinds of ANNs (multi-layer perceptron (MLP) and U-Net) were trained using DNS data to predict conformation stresses from given instantaneous fields. The MLP predicted the same tendency with DNS results and provided a better prediction with z-score normalization. The U-Net failed in accurate prediction even quantitatively, but both MLP and U-Net still suffered from the overfitting to the time slot of training data.

This paper describes deformational behaviors and strength of catheter made of soft nylon resin reinforced with thin stainless wires. In our previous study, the creep deformation behaviors of two stage step load, which is obtained under tension and torsion, have been examined. However, in those studies, the experiments have been done under non-water content condition, therefore the effect of water content condition has not been considered yet. In the present study, the creep deformation behaviors under water content condition, which are obtained under two stage step load with changing the order of tension and torsion, are investigated. Moreover, the analytical model for representing those creep behaviors are proposed. Then, the numerical simulations are performed and compared with those experimental results.

The purpose of this study is to examine the methods for distributing the residual bending moment efficiently along the irradiation direction in a thin metal plate. In our previous study, the method for obtaining the smooth distribution of residual moment has been considered by conducting the overlapping irradiation at the valley of the distribution of residual moment. Especially, the relations between the distribution of residual moment and irradiation distance, which are generated until the third time overlapping irradiation, have been examined in the previous report. Consequently, it is revealed that the additional overlapping irradiation must be considered when the irradiation distance is wide. In the present study, the numerical analysis for fourth time overlapping irradiation is conducted under the wide irradiation distance and these results are compared with previous numerical results obtained until the third time overlapping irradiation.

Permeability tensor of mushy region is very important to accurately predict macrosegregation in casting. In this study, we investigate the permeability changes in a plane normal to a columnar dendrite by employing phase-field and lattice Boltzmann methods. As a result, it is concluded that a two-dimensional permeability tensor with coordinate transformation agrees well with the present simulation results.

In this study, the adaptive mesh refinement (AMR) method is applied to a phase-field dendrite growth simulation using a graphic processing unit (GPU). To evaluate a computational efficiency of the implemented AMR method, dendrite growth simulations during directional solidification with and without AMR are performed. From simulation results, we confirmed that a good computational acceleration is achieved by the introduction of AMR.

QSI test analyses of CFRP laminate were carried out by FEM using interface elements considering cohesive zone model, which model delamination and matrix cracks. Damage propagation analysis was performed for four kinds of laminates with different geometries and stacking sequences, and the numerical results were compared with experimental results including relation between LPD and load, and delamination area. It was shown that the good correlation was obtained.

This paper deals with the simulation of the aerosol transport in an inclined cylindrical spray chamber for ICP-MS. In particular, the aim of this study is to predict the signal intensity and the stability, which is very important for spray chamber design. The fluid transport equations are solved in an Eulerian framework and droplets, which are dispersed phase, are represented as Lagrangian particles. In the simulation, droplets with diameters of 5 μm and 10 μm are introduced from the inlet of the spray chamber and the number of droplets at the outlet is counted. There is a positive correlation between the signal intensity obtained in the experiment and the number of droplets with a diameter of 5 μm obtained by calculation, as well as between the stability and the total number of droplets. As can be seen from a comparison of the results obtained from the experiment and calculation, computer simulation can successfully applied to design ICP-MS spray chamber.

CFRP laminates may have complicated formed damages resulting from delamination, matrix cracks, and fiber failure. Therefore, it is necessary to clarify the damage mechanism of CFRP laminate. In this study, damage propagation analyses of No Hole Tension (NHT) and Open Hole Tension (OHT) specimens of CFRP laminate are performed by XFEM. In the analysis model, Cohesive Zone Model (CZM) is introduced to interface elements modelling matrix cracks and delamination. A zig-zag softening law is employed for CZM to obtain converged solution by implicit static method. Moreover, selection of crack propagation law and influence of fracture toughness are discussed. It was shown that obtained results agree well with those by experiments.

By using Bayesian statistics, an approach to reduce the number of simulations in sensitive analysis is proposed. To verify the concept, we adopt a simple problem that a floating object collides to the wall by tsunami. The object is initially located at various positions in front of the wall. E-MPS is utilized to conduct the numerical simulation. As a result, it is expected to reduce the number of simulations to 64%. Though still more detailed research is necessary, usefulness of efficiency using the presented method is shown.

A hyper-elastic body is used for modeling materials that cause large deformation such as rubber. The finite element analysis method of the hyper-elastic body seems to be almost established. However, when implementing it, a problem arises that elements collapse by a large distortion. On the other hand, mesh-free method does not use mesh (element), so it may be robust against the difficulty encountered by the finite element method. The authors studied an improved mesh free method with higher precision and versatility than the conventional SPH solid analysis method, so we formulated the hyper-elastic analysis using the method, and studied the robustness of the method for the hyper-elastic body.

The formulation of the return-mapping for the subloading-friction model will be given in this article. Therein, the rigorous loading criterion will be formulated, which is applicable to the general loading process involving not only the monotonic but also the inverse loading processes.

While the plate material with circular holes is used for many engineering application, the design guidelines concerning the shape and arrangement of the places of holes are not described in the current JIS standard. Although the theoretical expressions which evaluate the stress value at the edge of the hole are required for infinite dimension plate and for finite width plate, no theoretical expressions can consider the length or the thickness of the plate.

In the present study, the purpose is to clarify the overall feeling how stress concentration, which occurs in the plate with a finite thickness, length and width having a single circular hole in the center of the face under an uniaxial tensile condition, depend on the thickness, length and width of plate using FE analysis. It is an advantage that FE analysis can freely consider the boundary condition on the both edges which are given the tension. The results under the uniformly distributed load condition and under forced displacement load condition are compared.

In the places without skilled physicians or equipment, primitive auscultation is beneficial instead of such image diagnostic method as electrocardiogram or MRI. Currently, an analysis system for grasping the heart condition from the heart sound is used for hospital examination, but it can be available under a somewhat skillful diagnostic expert. In the present paper, the interim course of development of heart sound diagnosis system which can be used even in the absence of a doctor, is explained. While clinical data may not be used, the authors create artificial learning data based on conventional medical knowledge to aim to construct a neural network which can diagnose disease name. As a first step, we discuss the possibilities of diagnosis to identify sound III.

The heart sound contains a lot of information which suggests the health conditions, while a skillful doctor is necessary for its diagnosis. The purpose of the present study is to create the system which automatically diagnoses diseases based on the heart sounds, which is available to everyone in the absence of a skilled physician. The authors perform creation of the heart sound used as input data of the neural network based on the heart sound recorded on CDs for medical education, and try learning it so that it can be diagnosed automatically. The results and discussions will be reported on the day after some trials with estimation of the learning accuracy by using test data.

Many fracture accidents of industrial structures are caused from fatigue crack in material. By complex shape of structure and other reasons, fatigue crack grows in the material under mixed mode cyclic loading. Therefore, exact evaluation of stress intensity factors are required to predict fatigue life of the structure including small crack. In order to evaluate stress intensity factors under mixed mode loading, the interaction integral method (IIM) is applied in 3D finite element analyses. In this study, referential solution for IIM is calculated from the component separation method for flat stationary crack problems. Solutions for stress intensity factors derived from IIM shows excellent results.

Chemical-Mechanical Polishing (CMP) is used to manufacture silicon wafers for the substrates for semiconductor devices and wafer flatness is determined mainly by this process. In this study, we have developed the simulation model of the polishing head consisting of a membrane with some air-bags based on finite element method (FEM) and calculated the pressure distribution on the surface of a wafer. The validity of the model and the control of the pressure distribution have been confirmed by the measurements of the pressure distribution, which show that the simulation model can be used to develop the polishing head.

In order to investigate the effect of strain rate and inner fluid on deformation behavior of the formed polyethylene (PE) film, the fluid-structure interaction analysis of the cell structure was carried out using SPH (Smoothed particle hydrodynamics)-FEM (Finite element method) analysis model. The analysis model was composed of cell walls, inner fluid and rigid walls. The cell walls were meshed using shell elements, and the inner fluid was replaced with the SPH particles. Air-filled and no-air models were prepared to investigate the effect of the inner air on the compressive properties. Even if the strain rate dependence was not defined for the constituent materials, it was confirmed that the effect of flow resistance of the residual inner fluid on the strain rate dependence of structural strength is remarkable when the internal fluid flows out. Therefore, in the quasi-static strain rate range, the strength increases due to the flow resistance of the residual inner fluid at the deformation and fracture of cell wall, which induces high strain rate sensitivity of the formed PE film. On the other hand, the increase in the strength due to the flow resistance of the residual inner fluid has reached the upper limit since the internal fluid does not flow out in the impact strain rate region. Thus, the strength of the formed PE film shows low strain rate sensitivity. From the above results, it was suggested that the deformation of the foamed PE film is influenced by the variation of flow resistance of the residual inner fluid with the strain rate.

Many industrial automotive or aerospace applications involve the analysis of the sound propagation, either radiated by vibrating structures or induced by a flow. Numerical simulation can be used as an efficient and robust alternative to experimental prototyping for both analysis and design. The finite element method has been widely used for tackling such NVH problems. In this paper, acoustic-structure interactive vibration is studied including the effect of Tuned Mass Damper, of which results are reported