Vehicle Structure Research Articles

Static mechanical properties and failure behaviors of self-piercing riveted joints in aluminum alloy 5A06 after aging

This paper conducts an investigation on the static mechanical properties and failure behavior of self-piercing riveted joints in aluminum alloy 5A06 after being subjected to the aging process. The study involves three distinct categories of joint specimens: original specimens, 1-year aged specimens and 1-year aged specimens that have been additionally heat-treated at 200 °C. The research findings affirm that strain aging is responsible for a reduction in the peak strength of the joints. Furthermore, the weakest failure chain within the self-piercing riveted joint shifts towards the upper sheet due to a more significant reduction in internal stress experienced by the upper plate. This leads to a failure model characterized by upper sheet pull-off. Through Weibull distribution analysis, it has been established that the 5 % lower limit value for the strength of the SPR joint experiences an 86 % decline following 1-year aging. In practical terms, this means that for a vehicle structure with 7000 riveting points will lose an overall structural strength equivalent to the initial strength of 1000 riveting points within one year.

Development And Characterisation Of Natural Hybrid Composites Using Abaca, Basalt, Glass Fibres

This paper proposes some considerations that are related to the impact protection of the battery pack, with particular reference to the side impacts against a fixed obstacle, such as a pole, We manufacture our battery cases from BASALT fiber, GLASS fiber(20% & 40%) in the form of sandwich composites material using Epoxy. The excellent properties of the fiber composite construction make the battery enclosure a supporting element of the vehicle structure.

Study on the effect of high temperature on the mechanical properties of composites plates containing initial defects

In this study, against the background of the high temperature environment faced by hypersonic vehicles, an in-depth study is carried out to investigate the influence of temperature on the mechanical properties of reinforced wall plates of composites containing initial defects. First, the in-plane shear mechanical property data and failure morphology of two groups of specimens of T1100/5405 composites at different test temperatures (25°C, 150°C) were obtained through experimental tests. The tests show that high temperature accelerates the damage failure process of the wall plate structure, the shear capacity of the wall plate is weakened, and the ultimate load decreases by 26.06%. Secondly, a numerical model based on the CZM and the CDM of the composite is established, and the accuracy of the model is verified by combining with the test results. The work carried out in this paper has certain engineering application value for the design of composite structures for hypersonic vehicles.

Research on Dynamics Characteristic of The Filling Liquid Tank

The dynamics characteristic of the rocket tank with liquid propellant in it, which takes the large part of a carrier rocket, make a great influence to the whole rocket. The tank of some model was investigated systematically by the PATRAN finite element software. Firstly, it established a finite element modal of the tank and calculated the modal frequency and shape of the empty or filling tank by the virtual fluid mass and acoustic-structure coupling analysis. Then, it contrasted the veracity and applicability of the two methods and investigated how the liquid depth and density and the middle clapboard’s thickness influenced the immanent frequency of tank. Further, the filled tank’s characteristic of response was researched by the coupled acoustic-structural analysis. Finally, it investigated how the liquid depth and density influenced the filling tank’s characteristic of response. The main conclusions are shown below:1.The result of the filling tank’s modal is approaching to the test.2.Augmenting the density of liquid reduces the modal frequency of tank and increases the pulsant pressure of liquid.3.Raising the depth of liquid reduces the modal frequency of tank and increases the pulsant pressure of liquid.The paper’s achievement and conclusion will help to avoid the coupling between the launch vehicle structure and propulsion system and improve the dynamic stability. It also can provide references for design of the new tank according to the result.

Investigations on the Johnson-Cook Constitutive and Damage-Fracture Model Parameters of a Q345C Steel

Due to the rapid development of high-speed trains, the service safety of vehicle body materials and structures has become a focal point in transport and impact engineering. Numerical simulations on the collision resistance of vehicle materials and structures are crucial for the safety assessment and optimal structural design of high-speed trains but have not been fully investigated due to the lack of damage model parameters. This study focuses on the Johnson-Cook (J-C) constitutive and damage-fracture models of a typical vehicle material, Q345C steel. A series of mechanical tests are conducted on the Q345C steel, including the quasi-static and dynamic compression/tension tests, quasi-static tension tests at different temperatures, and fracture tests along different stress paths, using the material test system and the split Hopkinson pressure/tension bar. Then, the parameters of the Johnson-Cook constitutive and damage-fracture models are calibrated based on the experimental results. In terms of the damage parameters related to stress paths, a new method of combining experiments and simulations is proposed to obtain the real, local fracture strains of the Q345C steel samples. This method allows the measurements of equivalent plastic strain and stress triaxiality histories under nonlinear stress paths, which are hardly accessible from individual experiments, and facilitates the accurate calibration of stress-path-related damage parameters. In addition, a high-speed plate penetration test is used to validate the J-C parameters, which can be directly implemented in the commercial finite element software Abaqus. The projectile trajectories from the simulation and experiment agree well with each other, demonstrating the reliability of the model parameters for impact scenarios and the efficiency of the experimental procedures utilized for calibration.

Predicting ground vibrations from railway tunnels using an improved 2.5D FEM-PML model with soil spatial variability

PurposeThis study establishes a method for predicting ground vibrations caused by railway tunnels in unsaturated soils with spatial variability.Design/methodology/approachFirst, an improved 2.5D finite-element-method-perfect-matching-layer (FEM-PML) model is proposed. The Galerkin method is used to derive the finite element expression in the ub-pl-pg format for unsaturated soil. Unlike the ub-v-w format, which has nine degrees of freedom per node, the ub-pl-pg format has only five degrees of freedom per node; this significantly enhances the calculation efficiency. The stretching function of the PML is adopted to handle the unlimited boundary domain. Additionally, the 2.5D FEM-PML model couples the tunnel, vehicle and track structures. Next, the spatial variability of the soil parameters is simulated by random fields using the Monte Carlo method. By incorporating random fields of soil parameters into the 2.5D FEM-PML model, the effect of soil spatial variability on ground vibrations is demonstrated using a case study.FindingsThe spatial variability of the soil parameters primarily affected the vibration acceleration amplitude but had a minor effect on its spatial distribution and attenuation over time. In addition, ground vibration acceleration was more affected by the spatial variability of the soil bulk modulus of compressibility than by that of saturation.Originality/valueUsing the 2.5D FEM-PML model in the ub-pl-pg format of unsaturated soil enhances the computational efficiency. On this basis, with the random fields established by Monte Carlo simulation, the model can calculate the reliability of soil dynamics, which was rarely considered by previous models.

A combination of “Inner - Outer skeleton” strategy to improve the mechanical properties and heat resistance of polyimide composite aerogels as composite sandwich structures for space vehicles

Low density aerogels with high fatigue resistance are widely used in the manufacturing of core material structures in aircraft fuselage to be able to tolerate the extreme environment of aerospace. However, most organic aerogel materials have poor energy absorption of external impact forces, and are prone to irreversible deformation, such as contracture and collapse in the process of long-term service. In order to solve this problem, a new type of thermosetting-thermoplastic polyimide composite aerogel was prepared, with its microstructure presenting the coexistence of the inner and outer skeletons. The intermolecular forces promoted the assembly of the soft thermoplastic layer and the strong thermosetting layer in the thermodynamic process with 4.63–6.55 μm range. The hard-soft layer structure improved the compressive and the shear load bearing capacities by bending of the panel (Compressive modulus is 1.60 MPa–3.52 MPa, tensile modulus is 1.04 MPa–1.45 MPa). Its permanent degradation less than 1.5 % after 500 cycles at 30 % strain. C–CPIAs also exhibited excellent heat resistance and thermal insulation performances, with a T5% value of 612 °C (C-CPIA-2), Tg of 458 °C (C-CPIA-3). The sandwich materials can be used as outer protective composite material of aircraft fuselage for future deep space missions.

Repeated impact response of honeycomb sandwich panels based on the failure parameters of adhesive layer and material

Honeycomb sandwich structure has been widely used in lightweight and impact protection of rail vehicle structures due to its excellent mechanical properties. In this paper, the plastic deformation, failure response and energy absorption characteristics of honeycomb sandwich panels for rail vehicles under repeated impact loads were studied. The three-point bending tests and low-speed impact tests of honeycomb sandwich panels were carried out, and a three-dimensional numerical model considering the detailed structure of the honeycomb core and the failure of the adhesive layer was established. The model can reasonably simulate honeycomb sandwich panels’ stiffness, strength, and structural failure. The effects of impact times and impact angle on the performance indexes of the honeycomb sandwich panel were studied. The results show that when the impact energy is the same, the impact times will affect the energy absorption distribution of honeycomb sandwich panels. With the increase in impact times, the panel’s absorption energy decreases, the core’s absorption energy increases, and the total absorption energy decreases. For multiple impact conditions, with the increase of impact times, the single energy absorption of the upper panel and core decreases, and the single energy absorption of the lower panel increases. When the impact energy is the same, the rise in impact angle will increase the damage to the honeycomb sandwich panel, and the energy absorption of each part will increase. In addition, the influence of impact times on the energy absorption efficiency of honeycomb sandwich panels is related to the impact angle.

Construction of Virtual Reality Rail Transit Simulation System

In order to enhance the quality of professional technology research and development and personnel training in rail transit, this study constructed a virtual reality rail transit simulation system, including the data input and processing of vehicle driving environment, vehicle structure and station scene data, as well as three-dimensional modeling and data storage. The data is stored in the Internet cloud server, which increases the accessibility and sharing of the data, and the rail transit simulation can be realized by calling the three-dimensional model in the cloud server. This efficient and convenient virtual reality content development tool helps to improve the level of scientific research and development and the quality of talent training in rail transit, it will also be the inevitable trend of the development of rail transit industry in the new era.

Materials design for hypersonics.

Hypersonic vehicles must withstand extreme conditions during flights that exceed five times the speed of sound. These systems have the potential to facilitate rapid access to space, bolster defense capabilities, and create a new paradigm for transcontinental earth-to-earth travel. However, extreme aerothermal environments create significant challenges for vehicle materials and structures. This work addresses the critical need to develop resilient refractory alloys, composites, and ceramics. We will highlight key design principles for critical vehicle areas such as primary structures, thermal protection, and propulsion systems; the role of theory and computation; and strategies for advancing laboratory-scale materials tomanufacturable flight-ready components.

Recovery of engine waste heat in low temperature environment of plug-in hybrid electric vehicle

The performance and life of electric vehicle power batteries will be reduced at low temperatures, and the lower temperature in the electric vehicle will also affect the comfort of drivers and passengers. Taking into account the winter temperatures and the unique drive structure of the plug-in hybrid electric vehicle, a specially designed driving mode for low-temperature environment is implemented. Based on this drive mode, a plug-in hybrid electric vehicle (PHEV) integrated thermal management structure is proposed to heat the battery and the passenger compartment, thereby improving energy efficiency. A mathematical model is used to establish the entire vehicle thermal management system, which is then experimentally validated. Under the NEDC (New European Driving Cycle) at ambient temperatures of −5°C, −10°C, −15°C, and −20°C, the calculation results of engine waste heat utilization and PTC (Positive Temperature Coefficient) heating are compared and analyzed. The results show that the average heating rate of the thermal management system proposed in this study is 23% faster than that of PTC heating at low temperature. The SOC decreases to 63.43% when engine waste heat utilization is adopted. When PTC heating is used, the SOC decreases to 49.18%. However, the advantage of the faster rate of engine waste heat compared to PTC heating becomes less pronounced as the ambient temperature decreases.

Визначення параметрів вібрацій космічного апарата на активній ділянці польоту ракети-носія на основі вогневих випробувань рiдинного ракетного двигуна

In orbital injection, the launch vehicle (LV) structure and the spacecraft are subjected to extreme dynamic loads, in particular to vibroacoustic loads (from rocket engine thrust oscillations and aerodynamic loads), which may cause spacecraft instrumentation malfunction and damage spacecraft light-weight thin-walled structures. This paper is dedicated to the development of an approach to predicting dynamic loads on spacecraft in orbital injection by LVs of various layouts under propulsion system thrust oscillations in active flight. The paper presents an approach to predicting dynamic loads on spacecraft in orbital injection by LVs of various layouts. The approach makes it possible to evaluate dynamic loads (spectral densities of vibration accelerations) on spacecraft under propulsion system thrust oscillations acting on the liquid-propellant LV structure in active flight. The approach includes a mathematical simulation of the spatial oscillations of the LV structure according to its structural layout scheme and the experimental pre-determination of the spectral density of the rocket engine power. The workability of the proposed approach in predicting the spacecraft dynamic loads is demonstrated by the example of a computational analysis of the spectral densities of spacecraft oscillations in orbital injection by LVs of various structural layouts. It is shown that the approach allows one to predict, as early as at the initial LV design stage, the spacecraft vibratory load parameters at different times of the LV first-stage liquid-propellant rocket engine operation accounting for the rocket layout (with the spacecraft) and design features and using the vibroacoustic characteristics of the liquid-propellant rocket engine (known from the results of its fire tests).

Feasibility study on the active structural attenuation of multiple band vibrations from two dimensional continuous structures in automotive vehicles

Automotive engine mounts have recently begun using active elements, while prior studies did not account for the actual engine mounting position. The placement and orientation of real automobile engine mounts are considered when modeling, analyzing, and controlling a source structure with an active mounting system. A piezoelectric stack actuator connected in series with an elastomeric mount composes an active mount. When harmonic excitation forces are used, the secondary force required for each active mount is mathematically determined, and the control signal may reduce the vibration by interfering with the input signal. Additionally, the dynamic relationship of the source structure with a variable parameter may be used to reduce horizontal vibrations. Several simulation findings show that these multidirectional (vertical and horizontal) active mounts may minimize excitation vibrations. Additionally, a simulation was performed to reduce vibrations when a complex signal and noise were present. This was achieved by monitoring the system response using the normalized least mean squares (NLMS) algorithm, an adaptive filter. The control performance degrades as noisy and complicated signals are generated; however, the mitigation trend is the same according to simulations utilizing adaptive filters.

3D CAD Model of Multifunctional Seat Used in Military Vehicle

Abstract: The primary postural strain experienced by the human body on extended off-road journeys is caused by the vibrations transmitted to the undercarriage and vehicle structure through the seat, as well as by the seating posture impacting the spine. The absorption of shocks and vibrations that happen during travel, linked to changes in speed and manoeuvres like braking, is crucial to minimizing vibrations. The effectiveness of vibration reduction relies heavily on the overall suspension system of the vehicle, particularly the design of the seats.

Analysis sedan vehicle structure in frontal impact using computer model

This paper presents an overview of Sedan vehicle structure based on frontal impact. The analysis results include parameters on the degree of deformation, the collision absorption ability of the Sedan vehicle structural model in accidents. The purpose is based on the comparison results to simulate the Sedan vehicle structure model that collides with other car chassis models at different speed levels, based on that, compares the crash analysis simulations to find the textures the frame absorbs the maximum impact energy and minimizes the deformation so as not to affect intrusion into the safe space of the passenger compartment of the vehicle. The results of this paper show that the frame structures such as the A-Pillars and Horizontal brace between the engine compartment and the passenger compartment need to be improved to increase the safety for the passengers inside. The study results are expected to be expanded in to optimize the engineering structures and improve the efficiency in various fields included shipbuilding, offshore structures, marine aquaculture structures, etc. Keywords: Structural, analysis, Sedan, vehicle structure, fontal impact.

A method for generating case-specific vehicle models from a single-view vehicle image for accurate pedestrian injury reconstructions

Developing vehicle finite element (FE) models that match real accident-involved vehicles is challenging. This is related to the intricate variety of geometric features and components. The current study proposes a novel method to efficiently and accurately generate case-specific buck models for car-to-pedestrian simulations. To achieve this, we implemented the vehicle side-view images to detect the horizontal position and roundness of two wheels to rectify distortions and deviations and then extracted the mid-section profiles for comparative calculations against baseline vehicle models to obtain the transformation matrices. Based on the generic buck model which consists of six key components and corresponding matrices, the case-specific buck model was generated semi-automatically based on the transformation metrics. Utilizing this image-based method, a total of 12 vehicle models representing four vehicle categories including family car (FCR), Roadster (RDS), small Sport Utility Vehicle (SUV), and large SUV were generated for car-to-pedestrian collision FE simulations in this study. The pedestrian head trajectories, total contact forces, head injury criterion (HIC), and brain injury criterion (BrIC) were analyzed comparatively. We found that, even within the same vehicle category and initial conditions, the variation in wrap around distance (WAD) spans 84–165 mm, in HIC ranges from 98 to 336, and in BrIC fluctuates between 1.25 and 1.46. These findings highlight the significant influence of vehicle frontal shape and underscore the necessity of using case-specific vehicle models in crash simulations. The proposed method provides a new approach for further vehicle structure optimization aiming at reducing pedestrian head injury and increasing traffic safety.

Determination of the Strength of a Container with Sandwich Panel Walls under Operational Loading Conditions

Purpose. The main purpose of this work is to present the results of determining the strength of a container with sandwich panel walls under the main operating modes of loading. Methodology. To ensure the strength of the bearing structure of the container, it is proposed to make its end and side walls from sandwich panels. This involves the creation of sandwich panels from two metal sheets, between which there is a filler in the form of an energy-absorbing material. The thickness of the sandwich panel sheets is determined by the Bubnov-Galerkin method. The sheet is considered as a thin-walled plate with the corresponding width and height parameters. To determine the strength of the load-bearing structure of a container with sandwich panel walls, the corresponding calculations were performed using the finite element method in the SolidWorks Simulation software package. The Mises criterion (IV theory of strength) was used as a calculation criterion. The spatial model of the container was created in SolidWorks. Findings. Taking into account the calculations, the rational thickness of the sheets, in terms of strength, of the side and end walls was established, which was 1.6 and about 3.0 mm, respectively. It is important that the use of rectangular corrugations makes it possible to reduce the thickness of the end wall sheet to 1.0 mm. The thickness of the side wall sheet is the same. The maximum stresses in the container in the case of its longitudinal loading occur in the fittings and amount to 268.3 MPa, which is 13.6 % lower than the permissible ones. The maximum stresses in the container under transverse loading were recorded in the areas of interaction between the side wall and the corner posts. The numerical value of these stresses was 178 MPa, which is 15.2 % lower than the permissible ones. Originality. The paper scientifically substantiates the use of sandwich panels as the walls of a uni-versal container. Practical value. The research will contribute to the creation of recommendations for the design of modern modular-type vehicle structures and improve the efficiency of the transport industry.

Research on dynamic characteristics of railway side-cracked slab for train-track coupled system

The Ballastless track have been extensively implemented in high-speed railways. However, during the long-term operational process, degradation, such as side crack or defect phenomena produced on the slab inevitably, poses a threat to the stability and the durability of the track structure. Consequently, it is imperative to propose a dynamic approach that can effectively predict the impact of side-cracked slab (SCS) on the vehicle-track coupled system. This paper utilizes co-simulation technology to investigate the dynamic behavior of the slab with and without side crack. Firstly, the dynamic substructure of the finite element model of the SCS is obtained by eigenvalue analysis. Secondly, the SCS model has been applied to the classical vehicle-track coupled dynamic system, and the coupled dynamic model of the train-side cracked slab (TSCS) is established, which considers the multi-rigid-body vehicle subsystem, the flexible rail subsystem, the flexible SCS and subgrade foundation subsystem, and the wheel-rail nonlinear contact model. Later, the accuracy and reliability of the proposed model are verified by the comparison with field tests. Finally, the differences in the vibration characteristics of the vehicle and track structure with and without a side crack are compared and analyzed, and its dynamic stress of the slab as variable train speeds is revealed. The results indicate that the existence of a side crack will reduce the natural frequency of the slab, with a maximum decrease of 22.31%. Although the SCS has a minor effect on the vehicle responses, the existence of a side crack has a significant impact on the slab, especially on the root mean square (RMS) of the vibration acceleration of the slab, with a maximum difference of 74.10% laterally and an increase of 55.16% vertically. Meanwhile, the train speed remarkably affects the crack tip dynamic stress of the SCS, with a maximum increase of 76.07% in the longitudinal direction, 50.34% in the lateral direction and 49.09% in the vertical direction. Higher train speeds will further exacerbate crack propagation under long-term train loading. This study may contribute to the dynamic modeling of TSCS systems and the maintenance of the slab ballastless track.

A method for modifying octagonal Goodman–Smith fatigue limit diagram

PurposeIn order to extend the application of the original octagonal Goodman–Smith fatigue limit diagram, which is commonly used for the evaluation of structure fatigue stress in engineering, a modification of it is proposed for the structure made of S355 steel (commonly used in high-speed electric multiple units (EMUs) bogie frame).Design/methodology/approachThe modification is made based on Deutscher Verband für Schweißen und verwandte Verfahren e. V. (DVS) 1612 standard and the γ-P-S-N curve, with consideration of the fatigue evaluation requirements of different survival rates and confidence levels. The verification of the modification is performed for three welded joints and for the comparison with the experimental data.FindingsThe results indicate that the design survival rate, the design safety margin and the fatigue stress evaluation of welded joint types are all improved by using the modified diagram.Originality/valueThere are relatively few studies on modifying octagonal Goodman–Smith fatigue limit diagram. In this paper, a modified diagram is proposed and applied in order to ensure the safety and durability of key welded structures of rail vehicles.

Evaluation of electric car styling based on analytic hierarchy process and Kansei engineering: A study on mainstream Chinese electric car brands

To evaluate the fuzzy and uncertain factors brought by human's emotional sensibilities during the design of new energy vehicle models, a scientific design evaluation method was adopted. This study combines the Analytic Hierarchy Process (AHP) and Kansei Engineering to assess the design of new energy vehicle models. It uses both objective criteria and subjective user perceptions. First, it quantified the design imagery vocabulary through Kansei Engineering and identified the target imagery vocabulary. Secondly, the AHP method was used to establish a relationship between design features and imagery vocabulary. Thrid, the study created an evaluation index system for design imagery, and adopted the fuzzy comprehensive evaluation matrix to rank the representative vehicles and brands in the Chinese new energy vehicle market. Based on the weight analysis results, the vehicle functionality (whether it is safe and reliable), the elegance of design, and the intricacy of vehicle structure were identified as the top three aspects that affect the impression of new energy vehicles. Therefore, we need to focus on these aspects during the design of new energy vehicles. Additionally, by integrating objective evaluation and emotional analysis results, we assessed the design for each new energy vehicle brand. The results of this study are important for developing the new energy vehicle market.