Modelling Deformations in Car Crash animation

In this paper, we present a prototype of a deformation engine to efficiently model and render the damaged structure of vehicles in crash scenarios. We introduce a novel system architecture to accelerate the computation, which is traditionally an extremely expensive task. We alter a rigid body simulator to predict trajectories of cars during a collision and formulate a correction procedure to estimate the deformations of the collapsed car structures within the contact area. Non-linear deformations are solved based on the principle of energy conservation. Large plastic deformations resulting from collisions are modelled as a weighted combination of deformation examples of beams which can be produced using classical mechanics

Scalable Real-Time Vehicle Deformation for Interactive Environments

This paper proposes a real-time physically-based method for simulating vehicle deformation. Our system synthesizes vehicle deformation characteristics by considering a low-dimensional coupled vehicle body technique. We simulate the motion and crumbling behavior of vehicles smashing into rigid objects. We explain and demonstrate the combination of a reduced complexity non-linear finite element system that is scalable and computationally efficient. We use an explicit position-based integration scheme to improve simulation speeds, while remaining stable and preserving modeling accuracy. We show our approach using a variety of vehicle deformation test cases which were simulated in real-time

Experimental implementation controlled SPWM inverter based harmony search algorithm

An optimum PI controller using harmony search optimization algorithm (HS) is utilized in this research for the single-phase bipolar SPWM inverter. The aim of this algorithm is to avoid the conventional trial and error procedure which is usually applied in finding the PI coefficients in order to obtain the desired performance. Then, the control algorithm of the inverter prototype is experimentally implemented using the eZdsp F28355 board along with the bipolar sinusoidal pulse width modulation (SPWM) to control the output voltage drop under different load conditions. The proposed overall inverter design and the control algorithm are modelled using MATLAB environment (Simulink/m-file Code). The mean absolute error (MAE) formula is used as an objective function with the HS algorithm in finding the adaptive values of  and  parameters to minimize the error of the inverter output voltage. Based on the output results, the proposed voltage controller using HS algorithm based PI (HS-PI) showed that the inverter output performance is improved in terms of voltage amplitude, robustness, and convergence rate speed as compared to PSO algorithm based PI (PSO-PI). This is to say that the proposed controller provides a good dynamic responses in both cases; transient and steady-state. Finally, the experimental setup result of the inverter controller is verified to validate the simulation results

Evaluation of coupled finite element/meshfree method for a robust full-scale crashworthiness simulation of railway vehicles

The crashworthiness of a railway vehicle relates to its passive safety performance. Due to mesh distortion and difficulty in controlling the hourglass energy, conventional finite element methods face great challenges in crashworthiness simulation of large-scale complex railway vehicle models. Meshfree methods such as element-free Galerkin method offer an alternative approach to overcome those limitations but have proved time-consuming. In this article, a coupled finite element/meshfree method is proposed to study the crashworthiness of railway vehicles. A representative scenario, in which the leading vehicle of a high-speed train impacts to a rigid wall, is simulated with the coupled finite element/element-free Galerkin method in LS-DYNA. We have compared the conventional finite element method and the coupled finite element/element-free Galerkin method with the simulation results of different levels of discretization. Our work showed that coupled finite element/element-free Galerkin method is a suitable alternative of finite element method to handle the nonlinear deformation in full-size railway vehicle crashworthiness simulation. The coupled method can reduce the hourglass energy in finite element simulation, to produce robust simulation

A Human Body Modelling System for Motion Studies

The need to visualize and interpret human body movement data from experiments and simulations has led to the development of a new three-dimensional representation for the human body. Based on a skeleton of joints and segments, the model is manipulated by specifying joint positions with respect to arbitrary frames of reference. The external form is modelled as the union of overlapping spheres which define the surface of each segment. The properties of the segment and sphere model include: an ability to utilize any connected portion of the body in order to examine selected movements without computing movements of undesired parts, a naming mechanism for describing parts within a segment, and a collision detection algorithm for finding contacts or illegal intersections of the body with itself or other objects. Several display algorithms are possible, including inexpensive hidden surface removal. The spherical body model can also be easily combined with planar polygon object environments

Finite Element Modeling of Rubber Bushing for Crash Simulation - Experimental Tests and Validation

Until recently, the general level of detail in full car crash models has not allowed a physical modeling of rubber bushings with solid elements. This is partly because of the difficulty in modeling the complex characteristic of rubber, but also due to limited understanding of the mechanical properties of rubber materials. The main focus of this Master’s thesis project is to develop a new and improved finite element modeling of rubber bushings for crash simulation, including the model of the bolt joint, which keep the rubber bushing linked to the body structure of the car. The final FE-model has to be able to mimic the real mechanical behavior of the rubber bushing and work effectively in the full-vehicle crash simulation. To achieve this, the program for non-linear dynamic analysis of structures in three dimensions LS-DYNA was used. In order to validate the final FE-model of the rubber bushing system testing activities and comparisons between the full-vehicle crash simulation with the new and improved FE-model of rubber bushing and the traditional one that often is used in the simulations were made. The experimental activities were carried out in the tower test of the Safety Centre of Volvo Car Corporation. In the first part of the thesis, comparisons between the finite element analysis and analytical solution of a simple cylindrical model of rubber exposed to shock loading as well as an estimation of the shear modulus G using the strain energy function of the Yeoh model and an energy balance has been done. The results from the FE-simulation corresponded quite well with the ones from the analytical solution when the Yeoh model is used as the hyperelastic rubber material to model the properties of the rubber. Regarding the FE-model of the rubber bushing system, the rubber part of the bushing was modeled in a rough way. This is because holes, fillets and other design features within the geometry of the rubber bushing rapidly increase the number of elements needed and, as a result, the computational cost of the analysis and the stability of the model are affected. Therefore, the smaller parts of rubber at the surface of the plastic outer sleeve, aluminum inner sleeve and at the corners while meshing the rubber bushing were not taken into account. The rubber bushing and the screw joint were modeled using 8-node solid elements, 4-node and 3-node shell elements and, 2-node beam elements. The 8-node solid elements were used for the rubber, the aluminum inner sleeve and the bolt head, the 4-node and 3-node shell elements were used for the plastic outer sleeve, the washer, the big nut and the cylindrical casing of the bolt, and the 2-node beam elements were used for the thread and the grip of the bolt. The Yeoh model was used to describe the hyperelastic behaviour of the rubber and for the rest of the model, the evaluated material models were mostly characterized by using elastic piecewise linear plasticity with a specific curve stress/strain and a yield strength. The contacts between metal and metal surfaces and between the rubber and the plastic outer sleeve were solved by using the simple global contact and the LS-DYNA option TIED_NODES_TO_SURFACE_OFFSET, respectively. The tightening of the bolt joint was taken into consideration in order to properly describe the friction and contacts between the different parts of the complete rubber bushing system from the beginning of the simulation. The rubber itself turned out to be just a small part of the complete rubber bushing system, so it was not necessary to use a complex material model to predict the physical response of the rubber. A simple and purely hyperelastic rubber material model where no damping exists was used instead. The Yeoh model worked out to be a stable model at high strain rate and therefore was used with theses material parameters: C10 = 0,55, C20 = 0,05, C30 = 0,95. The developed FE-model of rubber bushing system seems to model the nonlinearities in the system as large displacement effects and large deformations, material nonlinearity, and boundary nonlinearities. This is confirmed by the preload in the bolt joint, the contacts, the friction between the different surfaces and the bending and pulling out behaviour of the system working properly at the beginning and during the simulation. In order to validate the final FE-model of the rubber bushing system it was exposed to different loading cases in the FE-simulations and full-scale tests. The FE-simulations were tested under the same conditions as in the experimental tests in order to have a reference for comparisons. The full-scale impacts and computed deformations agreed qualitatively but they differed in magnitude. The deformations of the rubber bushing system, due to the bending moment, axial force and pulling out between sleeves appear to be similar to what happens in reality. The reason for the inaccuracies may be caused by several approximations in the FEmodel and others source of error while carrying out the different experimental test. An US-NCAP analysis was also performed in LS-DYNA in order to be sure that the final FE-model of the rubber bushing system works properly in the full-vehicle crash simulation. The simulation provided satisfactory results in the full-frontal impact of the car showing a significant improvement in the behavior of the rubber bushing system in comparison with the full-vehicle crash simulation of the traditional FE-model of rubber bushing that is often used in the car. Finally, the final FE-model of rubber bushing system can be considered reliable and can be used with a high rate of confidence in the full-vehicle crash simulation, since the computational time can be reduced by up to 4 % approximately and when used in the full vehicle crash simulation, this model is more physical and detailed than the traditional one and can better resemble the mechanical behaviour of the real rubber bushing system

A novel approach to modelling and simulating the contact behaviour between a human hand model and a deformable object

A deeper understanding of biomechanical behaviour of human hands becomes fundamental for any human hand-operated Q2 activities. The integration of biomechanical knowledge of human hands into product design process starts to play an increasingly important role in developing an ergonomic product-to-user interface for products and systems requiring high level of comfortable and responsive interactions. Generation of such precise and dynamic models can provide scientific evaluation tools to support product and system development through simulation. This type of support is urgently required in many applications such as hand skill training for surgical operations, ergonomic study of a product or system developed and so forth. The aim of this work is to study the contact behaviour between the operators’ hand and a hand-held tool or other similar contacts, by developing a novel and precise nonlinear 3D finite element model of the hand and by investigating the contact behaviour through simulation. The contact behaviour is externalised by solving the problem using the bi-potential method. The human body’s biomechanical characteristics, such as hand deformity and structural behaviour, have been fully modelled by implementing anisotropic hyperelastic laws. A case study is given to illustrate the effectiveness of the approac

Analysis and Prediction of Deforming 3D Shapes using Oriented Bounding Boxes and LSTM Autoencoders

For sequences of complex 3D shapes in time we present a general approach to detect patterns for their analysis and to predict the deformation by making use of structural components of the complex shape. We incorporate long short-term memory (LSTM) layers into an autoencoder to create low dimensional representations that allow the detection of patterns in the data and additionally detect the temporal dynamics in the deformation behavior. This is achieved with two decoders, one for reconstruction and one for prediction of future time steps of the sequence. In a preprocessing step the components of the studied object are converted to oriented bounding boxes which capture the impact of plastic deformation and allow reducing the dimensionality of the data describing the structure. The architecture is tested on the results of 196 car crash simulations of a model with 133 different components, where material properties are varied. In the latent representation we can detect patterns in the plastic deformation for the different components. The predicted bounding boxes give an estimate of the final simulation result and their quality is improved in comparison to different baselines

Development of Computational Model of Motorcycle and Rider During Collision

The goal of this project is to develop the computational model of motorcycle and rider for deformable body. Also, to identify the response of rider and motorcycle on collision.  Computational model is the one method that can replace the actual experiment on crash test. From the simulation can save cost by actual impact crash test. This project begins with design the model of actual motorcycle. Because the model of the project using Honda Wave 100R is to complex and the computer not powerful enough to generate mesh the simplified model is use for the project. Then, the material of this project using ANSI 304 stainless steel. The simulation of the experiment run by the ANSYS software to calculate mathematical model result after impact. Finally, the result of deformation was recorded to compare the result of deformation on actual crash test. The Comparison result of deformation actual and simulation are quietly simila