Simulation Of Impact Test Research Articles

Machine learning prediction of structural dynamic responses using graph neural networks

Prediction of structural responses is essential for the analysis of structural behaviour subjected to dynamic loads. Existing approaches are limited in different ways. Experimental tests are expensive due to the requirement of intensive labour hours and specialised equipment. Numerical models can provide high-fidelity and labour-effective simulation of impact tests after proper validation, but it comes with high computational costs, which prohibit the usage of numerical methods for intensive and large-scale simulations in a design office. Data-driven machine learning approaches are also applied to structural response predictions, but they often exploit direct input–output mapping schemes that predict static field variables without capturing the dynamic response process. To close these gaps, we propose a novel machine learning approach based on graph neural networks (GNN) for full-field structural dynamics prediction. Our approach adopts a discretised representation of structures with an iterative rollout prediction scheme, and therefore it can simulate comprehensive spatiotemporal structural dynamics, providing the full potential for structural dynamics analysis. With several benchmark tests, it is demonstrated that our approach can generate accurate predictions of related field variables, e.g., displacement, strain, and stress, for different structures with a wide range of input parameters, such as structure geometry, impact speed and location. Additional interpolation and extrapolation tests are also conducted to show that our approach enjoys inherent generalisability and can produce satisfactory prediction even when all inputs are sampled outside of the training distribution. Our approach is also efficient and runs an order of magnitude faster than the commonly used numerical competitors. As the first attempt of using GNN for structural dynamics prediction and the result is promising, it is believed that GNN is well-suited for effective and efficient prediction of dynamic structural responses.

Analysis and simulation of impact tests on automotive elements using two types of high-strength steels

This research, the main objective is to study and analyze the behavior of the automobile part called front bumper reinforcement, subjected to impact; For this, two types of materials belonging to the family of ultra-high strength steels will be used, since they are two materials that have excellent mechanical properties. To carry out the studies, a simplified model of said piece was increased; likewise, the analyzes will be developed with the help of CAE software. To carry out the process, a series of stages will be developed, ranging from the development of the model to be analyzed, considering its geometric study characteristics, as well as the knowledge of the mechanical properties of the materials to be worked on. In the same way, the conditions to which the element is subjected at the moment of impact will be known and applied. The force applied to the element will be subject to the speeds according to the standards used for this type of parts in impact tests. This research contributes to the studies of parts that are part of the safety of the vehicle, as well as knowing the mechanical advantages that 38MnB5 steel has compared to 22MnB5 steel.

Analysis of the Impact Resistance of Toecaps by the Finite Element Method: Preliminary Studies.

A key property in the manufacture of toecaps for protective footwear is resistance to impacts, deformations, and cracking, as the resulting defects may lead to serious workplace accidents involving the lower extremities. The present paper proposes a new approach to qualitative verification of toecap design based on numerical simulations of impact tests. Computational experiments were conducted for toecaps made from different materials (AISI 10450, S235, S355 and A36 steels, as well as Lexan polycarbonate) and characterized by different geometries, which were recreated by 3D scanning. The impact resistance of the toecaps was analyzed using a numerical model simulating an experimental impact test. The results were used to determine the location of critical stresses and to plot equivalent stress maps for the studied toecaps. The finite element analysis of the impact tests was carried out with an explicit elastoplastic finite element code: ANSYS (Ansys, Inc., Canonsburg, PA, USA) with the Explicit Dynamics module of the Workbench solver. The presented analysis of the impact resistance of toecaps by the finite element method for impact simulation may be used to optimize the spatial geometry of toecaps and to verify the construction of toecaps and the material deformations that may occur. In addition, it could eliminate unsuitable materials that are likely to undergo dangerous deformations, and draw attention to the deformation caused by the impact of the toecaps used in footwear in the working environment.

Validation of impact-absorbing football helmet facemask for head injury prevention with simulation

American football reports the highest rate of head injury in the United States. While football helmets have been developed to protect players and reduced severe head injuries, concussion incidents have not declined in the National Football League. A facemask is one of the helmet components mounted on the front opening of the helmet to protect the face, and it is the second most impacted location causing concussions. It is made of carbon steel or titanium and has high rigidity, which is effective at protecting the face from direct contact injury, but it is ineffective at absorbing impact. This study aimed to assess whether a facemask contributes to head injury prevention against front impact. We hypothesized that if a facemask absorbs impact, it would drop the concussion risk. We conducted a ram impact test and a helmet-to-helmet collision test to validate a facemask using numerical simulation. For the front ram impact test simulation, highly ductile polycarbonate plastic was applied to the facemask to cushion the impact. Various polycarbonate facemask designs reduced the head acceleration from the impact by more than 46% versus the titanium facemask. For severe helmet-to-helmet collision simulation with an angled front impact, a hybrid facemask composed of polycarbonate frame and steel wire decreased translational and rotational acceleration of the struck head and dropped concussion risk by approximately 50%. This study indicated that a facemask played a significant role in lowering concussion risk if it was designed to absorb impact.

Energy Absorbing Properties Analysis of Layers Structure of Titanium Alloy Ti6Al4V during Dynamic Impact Loading Tests.

This paper presents the testing methodology of specimens made of layers of titanium alloy Ti6Al4V in dynamic impact loading conditions. Tests were carried out using a drop-weight impact tower. The test methodology allowed us to record parameters as displacement or force. Based on recorded data, force and absorbed energy curves during plastic deformation and sheet perforation were created. The characteristics of the fractures were also analyzed. The impact test simulation was carried out in the ABAQUS/Explicit environment. Results for one, two, and three layers of titanium alloy were compared. The increase in force required to initialize the damage and the absorbed energy during plastic deformation can be observed with an increase in the number of layers. The increase in absorbed energy is close to linear. In the simulation process, parameters such as Huber–Mises–Hencky stress value, equivalent plastic strain, temperature increase, and stress triaxiality were analyzed.

Research on the effect of carbon nanotubes on cracking and impact properties of rubber aggregate mortar

Carbon nanotubes (CNTs) were added into rubber aggregate mortar (RM) as fillers. Three CNT gradients of 0.05%, 0.1%, and 0.2% were set to study the effects of different CNT contents on the fluidity, mechanical strength, cracking resistance , and impact performance of RM. The strain and displacement of the specimen's critical path during the impact process were analyzed by data simulation. As a result, CNT can reduce the fluidity of RM to a certain extent. The effect on mechanical strength, cracking property, and impact property of RM increases first and then decreases. When the content of CNT was 0.1%, the performance of RM was optimal, the flexural strength and compressive strength of 3d, 7d, and 28d are 6.3 MPa, 7.5 MPa, 8.7 MPa, and 30.3 MPa, 43.8 MPa, 52.1 MPa, respectively, increased by 46.5%, 38.9%, 29.9% and 43.6%, 53.7%, 40.1%, according to the control group. And the cracking time was 52.33 h, 16.1% longer than the control group. The first crack and failure impact times were 61 and 66, respectively, were greatly improved. Numerical simulation of impact tests found that the displacement of the specimen reached its peak value at 30°, 90°, and 150° along the circumference, which is consistent with the location of tensile damage. • The strength loss caused by rubber particles was compensated by the addition of CNT. • Carbon nanotubes can effectively slow down the cracking of rubber aggregate mortar and improve its impact resistance. • The stress state of U-shaped specimen under impact load is analyzed in detail by calculation.

Impact tests of wheels of road vehicles: A comprehensive method for numerical simulation

In the design of automotive wheels, safety is a crucial factor. Homologations, legislation and standards require severe impact tests before a new wheel can be released on the market. Impact tests are usually performed after the wheel has been already designed and the first prototypes have been produced. In case of test failure, significant delays and costs have to be sustained before the wheel can be actually produced. Numerical simulation of wheel impact tests can reduce the risk of test failure and be a valuable tool for the designer to obtain more efficient and light wheels.The paper deals with the full digitalization of the design process of road vehicle wheels. The aim is to reduce as much as possible indoor impact tests to assess wheel rim structural safety. The numerical simulation of impact tests is accomplished by complex finite element models comprising wheel, tyre and test rig structure. Several data can be required for the modelling of the tyre, which are not usually known to the wheel designer. In this paper, a method for the realization of finite element models of different impact tests is presented. By the proposed method, finite element models with a sufficient level of accuracy for the design of the wheel, at a relatively low computational cost, can be obtained by means of a well defined procedure. For tyre characterisation, only simple measurements related to geometrical features, stiffness and frequency response are required.The method is successfully applied to different impact tests such as radial impact tests with flat or V-shaped striker and 13∘ side impact test. For all the considered tests, experimental validations are performed on different wheels, instrumented with strain gauges located at the most stressed areas. The striker accelerations are also reproduced accurately.The method for the numerical simulation of indoor impact tests of road vehicle wheels enables the full digitalisation of design process, with relevant results in terms of ”time to market” reduction and structural safety assessment. The proposed method is useful not only to design wheel rims, but also to design pneumatic tyres.

A multi-stage material model calibration procedure for enhancing numerical solution fidelity in the case of impact loading of composites

The numerical prediction of impact-induced damage to composite materials and the subsequent residual strength under compression loading continue to be a challenging task. The current study proposes a calibration routine for optimizing the set of material model parameters prior to the virtual simulation of impact tests, which also simplifies the process of parameter determination. The calibration algorithm is based on the comparison of the numerical force-strain or force-displacement curves with the corresponding experimental ones to get the optimal input data, and it includes basic quasi-static material characterization tests. For the sake of simplicity, the calibration process was divided into two parts. The first part includes the in-plane loading tests (tension 0° & 90°, compression 0° & 90°, shear and open-hole tension) for calibration of orthotropic damage material model; whereas the second one consists of the mode I and mode II interlaminar fracture tests as well as the short beam shear test, and it mainly targets to the adjustment of cohesive model parameters. Given the optimal set of parameters of material models, low and high velocity impact simulations at the energy level of 30 J were carried-out to LS-DYNA software and compared with experiments. The percentage difference between numerical and experimental delamination area, after the calibration enablement, reduced from 77% and 60% to 10% and 25% for low- and high-velocity impact, respectively. Afterwards, the damaged specimens were experimentally and virtually tested to compression loading. In terms of maximum compressive load, the computational error is close to 1% for both impact conditions.

Numerical investigation on vibration characteristics and structural behaviour of different go-kart chassis configuration

Change in design of chassis, brings in (i) change in vibration pattern and (ii) stress pattern will also change for impact loading conditions. This paper aims to study the vibration characteristics and structural behaviour of three different Go-Kart chassis configurations. Chassis configurations are designed as per standards followed by major Go-Kart events organized in India and abroad. To study the vibration aspects, with change in design, modal analysis is done. Front, side and rear impact simulations are carried out to obtain displacement and stress distribution patterns. Three-dimensional CAD model is designed using SOLIDWORKS. Finite Element Analysis (FEA) software ANSYS Ver 16.0 is used to determine the Natural frequencies and impact testing. AISI 1018 material is taken for all the simulation cases. 4-G load is applied for front and rear impact while 2-G is applied for side impact test simulation. Results are extracted in terms of Natural Frequencies, von-Mises stress and deformation for all the simulation cases. Design 1 is found to have good vibration characteristics and is also possessing a higher degree of safety. The obtained results will be useful for students working to build their vehicle as well as industry people to fabricate safer and reliable Go-Kart vehicles.

Conceptual Design of New Bio-inspired Automotive Side Door Impact Beam

Side-door impact beam has been introduced to the passenger vehicles to reduce the door intrusion into passenger compartment during side impact collision. This study aims to develop the new bio-inspired design concepts of composites side-door impact beam. The integrated Theory of Inventive Principle – Function Oriented Search (TRIZ-FOS) and Biomimetics method is the idea generation technique applied in this research to develop the design concepts while the analysis of the generated design concepts using impact test simulation in finite element analysis (FEA) is the method to compare their performances. TRIZ (FOS) – Biomimetics method helps to transfer the nature technology into engineering problems and shows that it can generates five design concepts based on three nature technology which is toucan beak, pomelo peel and hedgehog spine in this study. The FEA analysis method then compared their strength, deformation, energy absorption and weight. In a conclusion, the integrated method of TRIZ (FOS) – Biomimetics helps engineers in generating the nature technology ideas to solve engineering problems using a structured method as proposed in this study while the FEA method really helps engineers to obtain the performances data for the design generated before proceed to the next step of product development process.

Finite element simulation of the micromechanical changes of the tissue and cells of potato response to impact test during storage by scanning electron microscopy

Abstract Impact damage in potatoes affects its microstructure and leads to quality loss. The finite element simulation of the micromechanical alterations in the tissue and cells of potato in response to impact test during storage by scanning electron microscopy (SEM) analysis have been investigated. Two macro-scale and micro-scale finite element method (FEM) models were developed to investigate impact damage of potato tubers and cells, respectively. Physical (density and turgor pressure) and mechanical (modulus of elasticity, yield stress, and tangent modulus) properties of potato tissue were determined during storage. Impact damage at the contact point and cell dimensions were obtained using the SEM images. A macro-scale FEM model, simulating impact damage of a tuber was meshed using the solid elements and the mesh size sensitivity was checked. A mesh is a group of interconnected finite elements joined together. The impact simulation scenarios included two impact levels of 0.032 J and 0.335 J at two week intervals during storage. The FEM results revealed that the maximum von Mises stress and impact damage increased at high impact energy while it decreased during storage. The impact damage prediction using the FEM model had a maximum error of 32.279 %. SEM images provided a reliable way to calculate the impact damage. The FEM simulation of impact tests on the micro-scale included a set of potato cells, each made of a cell wall and protoplast. The sensitivity of the mesh was checked and the appropriate element size for the potato tissue model was found to be 0.03 mm. The results showed a decrease in contact force due to the decrease in the elasticity modulus of the cell wall and protoplast during storage. Overall, it is concluded that the impact loading of potato after a period of storage leads to low impact damage and high quality of potato tissue.

Design, optimisation and analysis of a helmet made with graded honeycomb structure under impact load

Due to increased attention to safety requirements, energy absorbents such as honeycomb structures have gained increased importance. This study proposes a design for a graded honeycomb structure to use as energy absorbent in helmets in order to reduce impact load during traffic accidents. The honeycomb structure was designed with thickness of 5.9 mm form polypropylene and is covered with a ABS layer. European and UK standards were used for impact test of helmets. Impact test simulation was carried out in ABAQUS software. In order to evaluate the simulation method, numerical results were compared with experimental ones. Based on the results of tests using both standards, designed structure can absorb the applied kinetic energy. Also the measured reaction force, acceleration and HIC are lower than standard thresholds. The behaviour of the proposed honeycomb structure was also compared with a helmet which was made of EPS foam. The impact absorbent structure of helmets was optimised using genetic algorithm; then graded honeycomb structure was compared with foam and foam-filled structures. Based on the results of simulation, honeycomb structure absorbs energy for a longer duration and transfers impact force to the user with lower acceleration compared to EPS.

Experimental and Numerical Investigation of Charpy Impact Test of Spin Arc Welded C1018 plates

AISI 1018 low carbon steels are widely used in dynamic environment where material undergo sudden loads. In this study the Finite element simulation of impact test of Spin arc welded 1018 steel plates was analysed using Abaqus Explicit 6.14. Damage evaluation of spin arc weld and base metal are proposed by Johnson-Cook failure criterion model. The geometry, material and contact properties of base and weld metal are obtained from tensile test results. The specimen and striker are controlled by linear surface to surface interface. The numerical results are compared with experimental Charpy impact test for validation.

Impact test simulation and structural optimization of aluminum alloy A356.2 wheel hub

In order to improve the design efficiency of automobile hub, finite element simulation analysis is performed on the impact test of automobile hub. According to the national standard of impact test, Ansys Workbench software is used to load and constrain the explicit dynamics elastoplastic model. According to the results of impact strength analysis, the deficiency of the structure is studied, and put forward the corresponding structural optimization design. The actual test verifies the accuracy of the impact test simulation. Ansys software is used again to analyse the impact stress of the improved wheel hub to verify the rationality of the improved structure. The experimental results show that the method of dynamic analysis is practical and effective in calculating the stress and strain of automobile hub impact test. The research results provide theoretical basis and practical significance for the design and development of automotive aluminum alloy wheels.

Investigation on Potential of Recycle Plastic Bottles as a Crash Cushion for Road Barrier

Road accident is a major problem in the country and should be dealt with an effective ways. Road furniture is one of the factors that contributing an accidents than other factors. Therefore, this study focuses on waste material such as recycle plastic bottle that potential to be used as a road barrier and crash cushion. The objective of this study are to investigate the potential of plastic bottles filled with sand as crash cushion, examine the impact strength of plastic bottles and designing crash cushion by using recycled materials. Some plastic bottles of soft drinks containing ordinary sand was prepared and undergone experimental and simulation works. Free fall Impact test that imposed on the plastic bottles has been carried out to identify the strength and its energy absorption. The numerical simulation of impact test was conducted using Finite Element Method to obtain impact failure and to observe its details response under low velocity impact loads. The numerical results by employing FEM well agreed with practical works. Where, the absorption of energy from the impact test shows that the difference does not exceed 50%. In addition, the deformation of both test are almost similar. Therefore, the use of recycled materials such as plastic bottles filled with sand as crash cushions that can be considered as alternative and environmentally friendly materials.

Numerical Simulation and Experimental Drop Testing of Cocam-120-an Industrial Radiography Device

Gamma radiography devices are widely used in industries for Non-Destructive Examination (NDE). Board of Radiation and Isotope Technology (BRIT) has recently designed and developed COCAM-120 an innovative compact industrial radiography device. The device is designed as a Type B (U) package and can carry 120 Ci of Co60. To make design of COCAM-120 light in weight and compact in size, different shielding materials viz., Depleted Uranium, Tungsten and Lead are used optimally. Stainless steel is used as structural material and house the shielding material. One of the main design features is that indigenously developed Polyurethane Foam (PUF) encased in stainless steel is used as impact limiter. The PUF not only protect the device from the damage under 9m drop test but also act as a thermal barrier during fire test.Since, these devices carry radioactive material and move in public domain these packages need to demonstrate conformance to Type B (U) requirement, as per regulations of International Atomic Energy Agency (IAEA) and Atomic Energy Regulatory Board (AERB). One such requirement is that the package should maintain its structural integrity under 9m drop onto an unyielding target. Numerical simulation of impact tests are carried out using explicit finite element code PAM – CRASH specialized for a nonlinear dynamic simulation. The paper brings out the performance of the package under 9m drop on an unyielding target. The most damaging drop orientation was found out from simulation of different possible drop orientations. The instrumented drop test of full scale model of COCAM-120 on an unyielding target is performed. The numerical results and experimental results are presented and found to be in good agreement which demonstrates compliance with regulatory tests.

Ductile Fracture of Steel Sheets under Dynamic Membrane Loading

Failure prediction assessment is conducted based on validated finite element simulations of impact tests performed on 1.8 mm dual-phase and 1.0 mm martensitic steel sheets. The sheets were clamped between two steel rings and subjected to lateral loading by a punch with a hemispherical nose. Three different specimen geometries were applied. These were chosen to provide membrane loading in stress states near uniaxial tension, plane-strain tension and equi-biaxial tension. Thus, the most important stress states that may occur for thin sheets in an impact situation are covered. Finite element simulations of the impact tests are run with the nonlinear code LS-DYNA. The plastic behaviour of the materials is modelled using the Hershey yield function in combination with the associated flow rule and isotropic hardening. The specimens are discretized by shell elements, thus imposing a state of plane stress. Three different approaches for modelling ductile failure are evaluated by comparing the experimental and simulated force-displacement curves from the experiments on the two steel materials.

Multiscale Analysis of Open-Cell Aluminum Foam for Impact Energy Absorption

The energy-absorbing characteristics of crash members in automotive collision play an important role in controlling the amount of damage to the passenger compartment. Aluminum foams have high strength-to-weight ratio and high deformability, thus good crashworthiness is expected while maintaining or even saving weights when foams are implemented in crash members. In order to investigate the effect of the open-cell aluminum foam fillers on impact performance and weight saving, a multiscale framework for evaluating the crashworthiness of aluminum foam-filled members is used. To circumvent the difficulties of mechanical tests on foams, a micromechanical model of the aluminum foam is constructed using the x-ray micro tomography and virtual tests are conducted for the micromechanical model to characterize the behavior of the foam. In the macroscale, the aluminum foam is represented by the crushable foam constitutive model, which is then incorporated into the impact test simulation of the foam-filled crash member. The multiscale foam-filled crash member model was validated for the high-speed impact test, which confirms that the material model characterized by the micromechanical approach represents the behavior of the open-cell foam under impact loading well. Finally, the crash member design for maximizing the energy absorption is discussed by investigating various designs from the foam-only structure to the hollow tube structure. It was found that the foam structure absorbs more energy than the hollow tube or foam-filled structure with the same weight.

A numerical study on the influence of free water content on the ballistic performances of plain concrete targets

During the impact of a kinetic penetrator against a plain–concrete target severe damage modes are observed such as spalling on the front face, radial cracking in the whole target and, in the case of perforation, scabbing on the rear face. These damage mechanisms are substantially decreasing the penetration resistance of the concrete structure. Moreover, high confining pressures are observed in front of the projectile that involve mechanisms such as micro-cracking and collapse due to porosity. Both confined compressive and tensile behaviors are influenced by the concrete’s moisture content. Therefore, the constitutive model used for numerical calculation for describing the confined behavior and tensile resistance of the concrete has to take into account the amount of free water in the concrete. In the present work, a series of numerical simulations of impact tests have been conducted considering two saturation ratios (dry and water-saturated) plus two target thicknesses. The confined behavior of the concrete material is modeled using the KST (Krieg–Swenson–Taylor) plasticity model and the so-called DFH (Denoual–Forquin–Hild) anisotropic damage model which allows the description of the tensile strength and softening behavior of concrete in tension. These calculations are used to investigate the influence of the concrete’s free water content through its confined behavior and tensile strength and the influence of friction at the projectile–target interface on the ballistic performance of concrete slabs.

GS26 軟材料・軟組織の亜音速レベルにおける変形特性評価のための衝撃試験

Impact test at subsonic level is developed and applied to the evaluation of deformation behavior of soft materials such as biological soft tissue. The deformation resistance modulus of quasi-static examination is compared with that of the impact test at subsonic level. The results of the impact test at subsonic level are much higher than that of quasi-static examination in all materials. The material emulating a chicken are almost equivalent with a chicken breast in terms of deformation resistance modulus and behavior of the destruction. As a result of impact test simulation using the viscoelastic model applied deformation characteristic of chicken breast, the behavior of specimen crushed surface at the moment of ball collision is confirmed.