Lateral Impact Research Articles

Stability Study and Simulation of Quadruped Robots with Variable Parameters.

Walking stability is one of the key problems restricting the development of quadruped robots. Two new kinds of variable parameter quadruped robots with high stability were proposed. The two groups of variable parameter models were applied to quadruped robots with the full elbow joint or elbow joint for front legs and knee joint for back legs, respectively, and the stability of their linear motion under different variable parameters was deeply studied by Recurdyn. The quadruped robots with elbow joint for front legs and knee joint for back legs displayed good antijamming ability to lateral impact. According to the rigid-flexible simulation experiment, the largest force occurred in the knee joint during the movement of the quadruped robot. This provided a theoretical basis for the design of real quadruped robots.

Optimization for Side Structure of Vehicle Based on FEA

This paper takes the electric vehicle with HV battery traction which has achieved the "five-star" result of CNCAP as the research object, and uses HyperMesh and LS-DYNA to establish a lateral impact finite element model for simulation to verify the performance of this vehicle in C-IASI. In order to improve the performance of the side structure, the structure is optimized by upgrading the materials of key components, optimizing the key force transmission path and filling the cavity in the key deformation area with polymer structural stiffeners. According to the optimization scheme, the finite element model is established and calculated. The results show that the optimization scheme can effectively solve the problem of excessive intrusion and intrusion speed of the inner plate of the B-pillar in side impact, and improve the deformation mode of the B-pillar at the same time, improve the side impact safety performance of the vehicle, meet the requirements of "GOOD", and provide a reference for the solution of similar problems of subsequent related vehicles.

Design and Control of a Novel Leg-Arm Multiplexing Mobile Operational Hexapod Robot

A novel legged robot with 6 limbs driven by 20 proprioceptive motors, named SDUHex, is proposed in this letter. The limbs located at the middle of the robot can work as manipulators or locomotors. The topology design of the multi-mode robot is introduced and the kinematics and dynamics of the robot leg is analysed. A hierarchical optimized whole body controller with virtual model active compliance, called VM-WBC, is proposed. This control method unified the foot locomotion and arm operation. The terrain adaptation strategy is proposed to improve the non-flat terrain passability. A series of locomotion and operation experiments are carried out on SDUHex to test the designed robot and control method. Robust locomotion of the robot is verified by lateral impact recovery and slope terrain adaptation experiments. Arm operation of the robot including single-arm pushing and dual-arm picking are experimented to highlight the novel multiplexing function of the robot limbs.

Lateral Impact Response of Elliptical Hollow and Partially Concrete-Filled Cold-Formed Steel Columns Under Static Axial Compression Load

In recent years, the use of partially concrete-filled steel tubular (PCFST) columns has been considered due to their cost-effectiveness and reduction of structural weight in bridge piers and building columns. One of the critical discussions about these columns is their impact resistance. In this article, the dynamic response of hollow and PCFST columns with elliptical cross-section under simultaneous loading of static axial compressive load and lateral impact load is presented using finite element modeling in ABAQUS software (FEA). To ensure the accuracy of the numerical modeling, the analysis results are compared with the results of previous works. The effects of different parameters such as impact velocity, the height of the impact location, the impact direction, the impact block mass, the size and shape of the impact block are investigated in this paper. The results of the numerical analysis showed that the partially filled specimens had better performance than the hollow specimens. The changes in impact direction and impact block mass parameters have a significant effect on the failure of the columns, especially when they are under high impact velocity. Changing the impact velocity significantly affects the impact resistance of specimens. However, the size and shape of the impact block did not have a significant effect on the displacement of the column against the impact loading.

Crashworthiness behavior of reinforced circular tubes under lateral load impact

Crashworthiness behavior of reinforced circular tubes under lateral load impact

Toxicological effects of three different types of highly pure graphene oxide in the midge Chironomus riparius

Graphene oxide (GO) is a carbon nanomaterial used in electronics, biomedicine, environmental remediation and biotechnology. The production of graphene will increase in the upcoming years. The carbon nanoparticles (NPs) are released into the environment and accumulated in aquatic ecosystems. Information on the effects of GO in aquatic environments and its impact on organisms is still lacking. The aim of this study was to synthesise and characterise label-free GO with controlled lateral dimensions and thickness – small GO (sGO), large GO (lGO) and monolayer GO (mlGO) – and determine their impact on Chironomus riparius, a sentinel species in the freshwater ecosystem. Superoxide dismutase (SOD) and lipid peroxidation (LPO) was evaluated after exposures for 24 h and 96 h to 50, 500, and 3000 μg/L. GOs accumulated in the gut of C. riparius and disturbed its antioxidant metabolism. We suggest that all types of GO exposure can upregulate of SOD. Moreover, both lGO and mlGO treatments caused LPO damage in C. riparius in comparison to sGO, proving its favourable lateral size impact in this organism. Our results indicate that GOs could accumulate and induce significant oxidative stress on C. riparius. This work shows new information about the potential oxidative stress of these NMs in aquatic organisms.

Numerical investigation of hybrid UHPC columns subject to lateral impact

This paper presents extensive numerical and parametric studies on the dynamic performance of axially-loaded hybrid ultra-high-performance concrete (UHPC) columns subject to low-velocity impact loading. While existing studies have been performed on columns comprised fully of UHPC, the case of hybrid UHPC columns has not been fully explored. Hybrid columns involve the localised use of UHPC in combination with normal strength concrete (NSC) and can result in both performance and economic efficiencies. The present study uses Abaqus to develop a validated finite element (FE) model which allows exploration of key parameters such as impact location and energy, slenderness ratio and the length of the UHPC zone and their effect on hybrid column behaviour. It was found that localised adoption of UHPC at the predicted impact location significantly enhanced the performance and resulted in a change from brittle shear failure to flexural failure with minimal damage. The length of the UHPC segment was also found to have greater effect on columns with low reinforcement ratio. Meanwhile, the impact location was shown to have significant influence on the column response especially under a low pre-loading level. Hybrid columns experienced less displacement and higher plateau impact load under low impact energy. In comparison to the normal strength concrete column, the hybrid columns exhibited reduced mid-span displacement and increased impact load capacity which confirmed the ability of the UHPC segment to reduce the local damage resulting from the impact. In addition, in many cases, it was found that the application of higher pre-loading levels can provide an improvement in total impact performance of the hybrid columns. This is mainly attributed to the shifting of the pre-loading axis as a result of cracking at the top of the column ends. Finally, the presence of a UHPC segment with various lengths can change the location of the main (central) plastic hinge to the end of the UHPC segment, this reflects the ability of UHPC in improving the entire response of hybrid columns.

Pendulum impact loading tests of precast concrete columns with various column base connections

In the present study, pendulum impact loading tests were performed to investigate the lateral impact resistance of precast concrete (PC) columns with various column base connections. To maintain axial compression force during the impact process and subsequent collapse, a set of specially designed loading facility with solid counterweights was proposed. The test parameters included three PC columns using grouted sleeve connection (PC1), lap splice in grout-filled hole connection (PC2), and bolt connection (PC3), and a cast-in-place concrete (RC) column as a counterpart specimen. The dynamic responses including the damage mode, crack development process, impact force–time history, deflection-time history, strain–time history, and acceleration-time history were investigated. Further, the energy dissipation and stress wave transmission law of the specimen were analyzed. The test results showed that semi-rigid boundary conditions of PC columns decreased the column damage, but the lateral deformation increased, indicating relatively low impact resistance. The mechanical performance of each PC connection method was also discussed.

Experimental and Numerical Study of RC Square Members Under Unequal Lateral Impact Load

Reinforced concrete members under impact loading stress may be destroyed in a split period. Because of the need to investigate the impact resistance of reinforced concrete members, this issue remains a much-debated topic. This study investigates the response of reinforced concrete (RC) square members under an unequal lateral impact force. The performance of RC members under the effect of impact load is examined using a drop hammer impact test system. The importance of unequal lateral impact load is highlighted and addressed by examining RC members’ failure mode and dynamic response characteristics. Four types of RC members are experimentally investigated in detail. A finite element method (FEM) modeling is proposed to predict the impact responses of the RC members. Moreover, the effects of the impact position, height, and hammer mass on the dynamic response characteristics under an impact force are evaluated. The predictions of the proposed numerical model are validated against experimental results, emphasizing impact force history, deflection time history, and failure modes. Results indicate the viability of the FEM model. The findings from the experimental and numerical studies can improve the impact-resistant performance of reinforced concrete members.

Experimental and numerical investigation on the multi-optimization of reinforcing the side members of the vehicle structure

The aim of this study is to investigate the improvement in the strength of a top-hat profile hollow-section beam used in a vehicle structure by attaching different shapes of internal reinforcements. The base structure of the beam was first considered as a hat-shape structure which was jointed to a flat plate using spot-welds. Three types of sheet metal reinforcements were formed and attached inside the beam’s structure. Then, they were tested experimentally under low-velocity lateral impact. Also, a numerical simulation is being developed using LS-DYNA explicit code and validated using experimental data. Valid numerical configuration is used to conduct an optimization study on cross-sectional shape of the internal reinforcing component. Optimizations are carried out using single- and multi-objective methods based on Genetic Algorithm approach and the suggested optimum solutions are compared with experimental results. Moreover, to discuss the feasibility of applied reinforcements on side section of a vehicle’s body-in-white, a realistic side-pole crash test is simulated using a validated vehicle model and performance of improved chassis is compared with basic model and results are presented, discussed and commented upon.

Experimental and Numerical Investigation of the Polyurea-Coated Ultra-High-Performance Concrete (UHPC) Column Under Lateral Impact Loading

It was found that polyurea coating could improve the integrity and the corresponding durability of the structural components. However, the strengthening effect of polyurea coatings for structures built with emerging ultra-high-performance concrete (UHPC) is still unknown due to the lack of studies. Therefore, this paper investigated the effect of the polyurea coating on the lateral impact resistance of UHPC columns through a combined numerical and experimental study. A total of five specimens were fabricated, including two UHPC columns and three UHPC columns with polyurea coating. To better characterize the structural response under dynamic loading, impact cases with different drop weight impact heights and axial force ratios were employed. The results showed that the UHPC column with polyurea coating exhibited superior lateral impact resistance compared to the UHPC column. The presence of the axial force increased the lateral impact stiffness and further reduced the deflection of the specimen. In contrast, the polyurea coating improved the specimen’s ductility and mitigated the peak impact force, thereby maintaining the specimen’s integrity without sudden shear failure. A three-dimensional finite element (FE) model of polyurea-coated UHPC columns under impact loading was then established and confirmed the experimental results. With the validated FE model, an intensive parametric study was conducted to investigate the effects of polyurea thickness, axial force ratio and impact energy on the lateral impact resistance of the UHPC column. The presence of the polyurea coating could significantly improve the lateral impact resistance of the specimen, thereby preventing the shear failure of the UHPC column, and thus, the effective thickness of the polyurea layer for the UHPC column was determined to be 2–6[Formula: see text]mm. The outcome of this research demonstrates the great merits of polyurea coating in improving the ductility and integrity of the UHPC column under lateral impact loading.

Dynamic behavior and damage assessment of RC columns subjected to lateral soft impact

In this study, the performance and damage behavior of reinforced concrete (RC) columns under lateral soft impact are comprehensively investigated using 3D finite element (FE) analysis. Firstly, refined FE models of RC columns are developed in LS-DYNA, and the corresponding simulation techniques are verified against existing experimental testing data. Then, response characteristics of a typical column under soft impact are examined, and a section damage factor is defined to quantify the damage evolution of impacted columns. After that, the effects of various design parameters, including impactor stiffness, impact elevation, axial force ratio, section dimension, and combination of impact mass and velocity, on the dynamic behavior of columns are examined. Finally, criteria for both flexural damage and shear damage are proposed based on the section damage factor, and the resistance dynamic increase factor (RDIF) of RC columns under soft impact is utilized to establish a rapid damage assessment methodology. From these results, it is proved that the dynamic responses and failure modes of RC columns under soft impact are quite different from those under hard impact. The impactor stiffness and impact elevation have a significant effect on the mechanical mechanism of columns, and the column resistance generally increases with the axial force to a certain extent. In addition, RDIF of columns decreases with the increase in the ratio of the impact time at peak force tp to the column natural period Tcol.

Simplified Model of a High Burnup Spent Nuclear Fuel Rod under Lateral Impact Considering a Stress-Based Failure Criterion

The inventory of spent nuclear fuel (SNF) generated in nuclear power plants is continuously increasing, and it is very important to maintain the structural integrity of SNF for economical and efficient management. The cladding surrounding nuclear fuel must be protected from physical and mechanical deterioration, which causes fuel rod breakage. In this study, the material properties of the simplified beam model of a SNF rod were calibrated for a drop accident evaluation by considering the pellet–clad interaction (PCI) of the high burnup fuel rod. In a horizontal drop, which is the most damaging during a drop accident of SNF, the stress in the cladding caused by the inertia action of the pellets has a great effect on the integrity of the fuel rod. The failure criterion for SNF was selected as the membrane plus bending stress through stress linearization in the cross-sections through the thickness of the cladding. Because the stress concentration in the cladding around the vicinity of the pellet–pellet interface cannot be simulated in a simplified beam model, a stress correction factor is derived through a comparison of the simplified model and detailed model. The applicability of the developed simplified model is checked through dynamic impact simulations. The developed model can be used in cask level analyses and is expected to be usefully utilized to evaluate the structural integrity of SNF under transport and in storage conditions.

Use of a Simulation Model to Investigate the Mechanisms of Sports-related Head Injuries.

A simulation model was developed to better understand the mechanisms of brain injuries in sports. A three-dimensional model comprising approximately 1.22 million elements was constructed from cranial computed tomography images of adult male volunteers by the voxel method. To simulate contact sports that permit actions such as tackling, a sinusoidal wave with duration of 10 ms and maximum acceleration of 2000 m/s2 was applied to the lowest point of the model to apply rotational acceleration to the head from different directions. The von Mises stress was then observed at five points in the coronal plane of the brain: cingulate gyrus (CG), corpus callosum (CC), brain stem (BS), lateral temporal lobe (LT), and medial temporal lobe (MT). LS-DYNA universal finite element analysis software with explicit time integration was used for the analysis. Concentrations of stress started to appear in the CC and BS at 10 ms post-impact, after which they also became evident in the CG and MT. The maximum changes in stress at each location occurred 10–15 ms post-impact. The von Mises stress was 9–14 kPa in the CG, 8–24 kPa in the CC, 12–24 kPa in the BS, 7–12 kPa in the LT, and 12–18 kPa in the MT. The highest stress in every part of the brain occurred after lateral impact, followed by oblique impact and sagittal impact. Such simulations may help elucidate the mechanisms of brain injuries in sports and help develop measures to prevent chronic traumatic encephalopathy.

Study on the nonlinear response and shear behavior of RC columns under lateral impact

In the present study, in view of the problem of nonlinear response caused by vehicle-RC pier collision, a new test system which can realize lateral impact is proposed, and two types of 1:3 scale RC components in five groups are subject to the lateral impact test at a velocity of 4.5 m/s. The system’s design characteristics represent the effect of stirrup spacing and axial compression ratio on the dynamic response of RC columns. In addition, the nonlinear response results of RC columns, such as impact force, acceleration, lateral displacement, failure mode and degree, are given in the test. Digital Image Correlation (DIC) technology is applied to the test. Next, the lateral strain response of RC columns during impact is measured, and the strain change process in every representative region is calculated. The data outlined in this study provide a reasonable basis for evaluating the shear capacity of RC columns and developing a finite element model (FEM). Finally, a typical FEM of vehicle-pier collision scenario is developed, while an improved equation for calculating the axial compression ratio-shear increment and a simplified calculation value of dynamic shear capacity of the RC pier are proposed.

Analysis of Energy Absorption Distribution for Circular Concrete-Filled Steel Tubular Members under Lateral Impact

A nonlinear finite element model of the circular concrete-filled steel tubular (CFST) member under lateral impact is established based on the existing drop weight tests, and the accuracy of numerical simulation is validated by comparing with the test results. Then the segmented numerical model of the circular CFST member is divided evenly to obtain the distribution of energy consumption along its length. The results indicate that the prime areas of energy consumption for the circular CFST member are distributed at the impact position (within 1/6 of the effective length) and the support position (within 1/12 of the effective length). On this basis, the affect of impact position on energy absorption distribution is carried out to reveal the changes of the prime areas of energy consumption. The results of this investigation can provide a reference for the impact resistant design and damage reinforcement of circular CFST members under lateral impact.

Experimental and numerical study on the dynamic response of steel-reinforced concrete composite members under lateral impact

This paper investigates the dynamic response of steel-reinforced concrete (SRC) composite members under lateral impact using experimental and numerical studies. A total of 11 specimens composed of structural steel encased in reinforced concrete were tested under drop hammer impacts. The dynamic responses of SRC members including damage observations, impact force, and mid-span displacement were obtained and analyzed with emphasis on the effect of impact velocity, boundary condition, and axial load. It was found that the specimens failed in a shear–flexural response and impact velocity played a significant role in determining the dynamic response of SRC members. It was also found that the amount of residual displacement was linearly proportioned to the displacement ductility. Followed by the experimental study, a finite element analysis (FEA) model was established and verified based on the test results. The distributions of impact energy among different components are obtained using FEA models. It was found that the energy dissipation was dominated by concrete rather than structural steel or reinforcement. However, with the increase in impact energy, the percentage of energy dissipation in the structural steel increases, meaning that encasing structural steel in concrete elements is an effective method to improve impact resistance.

Analysis of ground reaction forces and muscle activity in individuals with anterior cruciate ligament reconstruction during different running strike patterns.

Anterior cruciate ligament reconstruction provides successful clinical outcomes. However, reconstruction cannot restore normative lower limb mechanics during running. While numerous studies have investigated running characteristics in individuals with anterior cruciate ligament reconstruction, no study has been compared foot strike patterns among them. If ground reaction forces and lower extremity muscle activities in individuals with anterior cruciate ligament reconstruction and healthy control ones differ during three running strike patterns? In this cross-sectional study, fourteen healthy adult males and fourteen adult males with anterior cruciate ligament reconstruction were recruited to participate. Surface electromyography of selected lower limb muscles and ground reaction forces were measured during three-strike patterns: rearfoot strike pattern, midfoot strike pattern, and forefoot strike pattern during barefoot running (∼ 3.3 m/s). The results revealed that the strike patterns influenced the peak lateral ground reaction force (P < 0.001) and peak vertical impact ground reaction force (P = 0.002) during the stance phase of running for both groups. The strike pattern also influenced the tibialis anterior (P < 0.001) and vastus lateralis (P = 0.035) activities during the early stance phase for both groups. However, the vastus medialis (P = 0.030) presented reduced activity, and the biceps femoris (P = 0.039) presented increased activity in the anterior cruciate ligament reconstruction group. Tibialis anterior (P = 0.021), gastrocnemius medialis (P < 0.001) and vastus medialis (P < 0.001) presented lesser activity irrespective of strike patterns in the anterior cruciate ligament reconstruction group. Running with a forefoot strike pattern may be associated with lesser rearfoot eversion due to lower peak lateral ground reaction forces than running with a rearfoot strike pattern or midfoot strike pattern. Moreover, the altered muscle activities could contribute to the elevated risk of future joint injury in the anterior cruciate ligament reconstruction population.

Potential effect of pre-activated muscles under a far-side lateral impact

Objective The goal of this study is to evaluate the potential effect of muscle pre-activation under a lateral impact scenario, in this case focusing on a far-side impact, using an Active Human Body Model. Methods In total fourteen simulations were run, out of these, twelve were computed with an Active Human Body Model and two with a passive one. The models were subjected to a far-side impact scenario reaching up to 14 g’s. Two different pre-crash scenarios were analyzed with the Active Human Body Model: (1) constant velocity, and (2) braking deceleration. During the pre-crash phase a lambda control based on the muscle length computed the muscle activation. Since there is no available data concerning the neuromuscular strategy of the occupants subjected to high accelerations, six different control strategies were analyzed during the in-crash phase. Besides, rib fracture and brain injury risk were analyzed, since they are the two most relevant body regions in this simplified far-side crash scenario. Results The pre-activation of the muscles showed an effect on both the occupant kinematics and estimated injury risks. Depending on the considered muscle strategy, the head lateral excursion varied up to 75 mm, specifically for the scenario with constant velocity. Moreover, the rib fracture probability and the brain injury indicator revealed higher injury risks for the passive Human Body Model. When applying the constant velocity during pre-crash, the fracture probability for two or more ribs ranged from 9.91 to 46.06% for the Active Human Body Model, whereas it reached 84.3% for the passive model. The brain injury indicator was reduced by about 10% when using the active model compared to the passive one. Conclusions The numerical results show that the pre-activation of the muscles affects the kinematic and injury outcomes in car crashes. In this study, six muscular control strategies have been proposed. The two muscular controls that may be most realistic are: constant activation after the in-crash phase starts, by trying to hold the position prior to the crash, or no stimulation, by not responding to the upcoming in-crash event.

Dynamic derailment behaviour of urban tram subjected to lateral collision

ABSTRACT The urban tram is theoretically likely to be laterally collided by the automobile during operation due to their shared right of roadway. The collision occurrence is fortuitous, but the consequence is commonly disastrous induced by the collision and subsequent derailment accidents. This article presents an investigation into the derailment performance of the tram when the automobile impacts laterally onto the tram flank. A comprehensive dynamic model to simulate derailment behaviours of the tram under this collision scenario is built, in which the complicated contact relation of wheel/rail system is treated. The contribution of several affecting factorsto the derailment response is reported. It is shown that the guardrails of the grooved rail track play a key role in preventing the tram derailments due to low-speed collision. The violent lateral and rolling motions of the tram body caused by the great lateral impact is the root cause of the derailments.