Browse Topic: Protective structures
With new energy vehicles developing rapidly, battery safety, as an important part of the impact on the range of new energy vehicles and vehicle safety, has become the focus of attention. The battery pack protection plate is a core component to protect the battery, its performance needs not only impact resistance, but also lightweight, honeycomb sandwich structure with its excellent energy absorption characteristics and weight reduction performance by the battery pack protection plate performance research. At present, the core-to-face sheet interaction in conventional sandwich structures subjected to impact loads has not been fully elucidated, and the quantitative characterization of damage is insufficient, so this paper aims to optimize the lightweight impact-resistant structure by exploring the synergistic energy dissipation mechanism between the high-strength core material and the steel plate. The study combines theory and simulation, adopting ideal rigid-plastic film theory to establish a critical response model to predict the structural failure threshold, equivalent single-layer theory to simplify the analysis of plywood, and a stiffness matrix model to quantify the structural mechanical contribution of each layer. A two-material synergistic design framework is proposed by fully considering the material properties and adopting the corresponding intrinsic structure and failure criteria for different materials. Analysis reveals that geometric confinement is a key characteristic of the honeycomb sandwich panel’s response and a strain gradient driving mechanism at low impact resistance, and a new energy distribution paradigm is found through the analysis of the energy absorption ratio. The theoretical and simulation results are in great agreement with each other, which just has a difference of 0.7% in the peak force, 1.4% in the critical displacement error, and less than 2% in the impulse integration error. The proposed dual-material co-design framework provides a solution for electric vehicle battery protection systems that balances lightweight and impact resistance.
In the automotive industry, the electric vehicle is the new era, and companies are committed to reducing carbon emissions by electrification of their vehicles. In the development of electric vehicles, the battery is the central power source for all the parts of the vehicle. Usually, it is placed under the body because of its size and mass. So, it is important to protect battery cells from leakage and damage from obstacles. For on-road electric vehicles, speed bumps are one of the crucial obstacles. This paper investigates and analyses the protection of battery pack systems in electric vehicles while encountering speed bump profiles at different speeds. During the physical test on a speed bump, there is a possibility of bump hit on the battery pack system and it is necessary to ensure the structural safety of the battery pack systems. In this study, CAE method has been developed to validate the battery pack system in the event of a speed bump crossing. Virtual simulation analysis was performed in the full vehicle FE model and measured the impact energy at various locations and acceleration on the battery pack. Virtual results are well correlated with test measurements at various locations on the battery pack system. Based on the correlation results, CAE provides design suggestions and verified in physical test.
ABSTRACT Midé Technology Corporation (Midé), a Hutchinson company, in collaboration with The University of Texas at Austin (UTA), have investigated the potential for novel negative stiffness (NS)-based structures as blast resistant vehicle panels. Protecting vehicles from blast shockwaves would ideally minimize added weight and maximize reusability. Homogenous metal panels provide such protection but without the benefit of reusability, absorbing energy via plastic deformation, while also adding significant weight to a vehicle, thereby sacrificing mobility. Although various emergent approaches, including the use of hexagonal honeycombs and auxetic materials, have proved promising in terms of higher energy absorption per unit mass, such approaches also rely on plastic deformation additionally suffering from the drawback of occasionally transmitting a higher peak force as compared to the incident.
Off-road trucks, tractors and earth-moving machines are at high risk of accidents involving falling objects or rollovers. Therefore, these machines need proper protective structures to protect operators. This study investigates the crashworthiness optimization of a hydraulic excavator cab roof rail based on an improved bi-directional evolutionary structural optimization (BESO) method considering two different load cases (a lateral quasi-static load and an impact load from the top of cab, respectively). In the crashworthiness optimization problem, a weighted summation of external works done by the two different load cases is treated as the objective function while the volume of design domain is treated as the constraint. A mutative weight scheme is proposed to stabilize the optimization and balance the two load cases. Finite element (FE) model is established and two prototypes are fabricated based on the optimal design. Explicit FE analysis is used to predict the performance of roll-over protective structure (ROPS) and falling-object protective structure (FOPS) under standardized laboratory test. The smooth evolution histories of reaction forces demonstrate the effectiveness of mutative weight scheme. The simulation-based test results for the ROPS and FOPS have a close agreement with the experimental test results. The accuracy and efficiency of the FE analysis are high enough to predict the behaviors of ROPS and FOPS under the laboratory tests.
Tractor weight transfer is the most common farm-related cause of fatalities nowadays. As in India it is getting mandatory for all safety devices across all HP ranges. Considering any changes in the weight from an attachment such as Rops, PTO device, tow hook and draw bar etc. can shift the center of gravity towards the weight. center of gravity is higher on a tractor because the tractor needs to be higher in order to complete operations over crops and rough terrain. Terrains, attachments, weights, and speeds can change the tractor’s resistance to turning over. This center of gravity placement disperses the weight so that 30 percent of the tractor’s weight is on the front axle and 70 percent is on the rear axle for two-wheel drive propelled tractors and it must remain within the tractor’s stability baseline for the tractor to remain in an upright position. In our present study formulating the prediction of tractor CG by using a modified excel spreadsheet package employing the parameters of the model, tractor CG were then determined. Finally, the effects of changes in the parameters of the model were evaluated and results of the analyses indicate the changing the tractor CG about the x-axes and y-axes have an influence on the weight distribution of the tractor from front and rear wheel, whereas increasing the tractor weight percentage on the front wheel have an benefit of tractor less lifting on the front end.
An All-Terrain Vehicle (ATV) as defined by the American National Standards Institute (ANSI) is a vehicle that travels on low pressure tires and with a seat that is straddled by the operator, along with the handlebars for steering control. A roll cage can be defined as a skeleton of an ATV. It forms a structural base and 3-D shell around the driver. In case of impacts and roll over incidents, the roll cage is responsible for the protection of driver. The objective is to design, analyze and optimize the roll cage under a set of particular rules given by Society of Automotive Engineers (SAE). The static analysis is carried out using CATIA V5 software for different collisions like front, side, rear and roll over. The main objective of the analysis is to obtain a roll cage enough strong to bear such adverse conditions as well as light in weight for better performance. The safety of roll cage can be ensured by obtaining optimum factor of safety.
Tractor roll over is the most common farm-related cause of fatalities nowadays. ROPS (Roll-Overprotective Structures) are needed to prevent serious injury and death. It creates a protective zone around the operator when a rollover occurs. In India the ROPS is getting mandatory across all HP ranges except narrow track. In the present study states the customized ROPS application for configurable design such as Automated safety zone for all homologation standards, ROPS A0-D excel calculator for selection of material at concept stage and bolt calculator for selection of size. For the above applications below aspects need to consider such as Tractor weight, Rear housing mounting, Operator seat index position (SIP), Seat reference points (SRP) and all ROPS homologation standards. This ROPS application is to reduce the timeline, manual error and ensure the reliability of the modular optimal design for various platforms and variants. Nowadays it is important to perform configurable design at the concept design phase across variants/platform wise including all individual parts (both assembly & child part) so that we can optimize the varieties of material and thickness used, which will reduce the development & validation cost and shorten the time-to-market in later stages. Stochastic design optimization is then performed to reduce the weight of ROPS and ensure the robustness with reliability of the modular optimal design also in this paper. A ROPS design application is an example to demonstrate the proposed methodology by using NX10 - Automation, MathApps for bolt Calculator and ROPS A0-D excel calculator for determine the energy absorption capacity of the ROPS. Application results provide us the review and feedback on the safety and rigidity of the optimized ROPS for different platforms.
NASA Goddard Space Flight Center has developed a magnetic shielding design that features simplicity, ease of use, reproducibility, longevity, and scalability. It does not require activation, monitoring, or wiring. The invention uses the superconducting “proximity effect” and/or the “inverse proximity effect” to form a spatially varying order parameter. When designed to expel magnetic flux from a region of space, the proximity effect(s) are used in concert to make the superconducting order parameter strongly superconducting in the center and more weakly superconducting toward the perimeter. The shield is then passively cooled through the superconducting transition temperature.
To protect ship equipment of river and sea transport, it is suggested to use polymeric protective coatings based on epoxy diane oligomer ED-20, polyethylene polyamine (PEPA) curing agent and filler, which is a departure from industrial production. Thus the purpose of the work is analysis of major dependency of the properties on the content of fillers that allowed to revealed the critical filler content (furnace black) in composites to form a protective coating with the required set of characteristics. The infrared (IR) spectral analysis was used to investigate the presence of bonds on the surface of particles of the PM-75 furnace black, which allows us to assess the degree of cross-linking of the polymer. The influence of the content of dispersed furnace black on the physicomechanical and thermophysical properties and the structure of the protective coating is investigated. For the formation of the coating with increased adhesive properties, the optimum content of the additive is q = 25 parts by weight (pts.wt.), due to the increase in the number of C—O, C—C, C═O, C═C, C═O, and O═C—H bonds. For the formation of the coating with increased cohesive properties, the optimum content of the additive is q = 20 pts.wt., which is associated with the maximum compaction of the polymer spatial net. On the basis of the analysis of the surface of the composite fracture, a homogeneous topology of the fracture surface was found which characterizes the viscous state of material destruction at the content of the additive q = 5 pts.wt., which provides significant improvement of the physical and mechanical properties of the materials developed. Additionally, it was found that when the PM-75 particles were introduced at the content of q = 10-30 pts.wt., the uniformity of the structure is retained, but its abnormal similarity is observed. This allowed us to determine the optimal content of the additive (q = 20 pts.wt.) for the formation of coatings with high cohesive strength in the complex.
This paper discusses a simplified analytical/experimental method for evaluating and designing large buses and motor coaches for rollover protection. The proposed method makes use of the work-energy principle in analyzing the energy-absorbing capacity of the roof and sidewall structure of the vehicle. The basic structural unit is treated as a nonlinear, elastoplastic, 4-bar linkage, with the links connected at hinge points. During rollover, the deformation of the structure is focused at these hinge points and energy absorption is achieved through plastic bending and rotation of the hinge material. The proposed method allows the evaluation and design of these plastic hinges to achieve the energy-absorbing requirements for the vehicle. This paper demonstrates the proposed methodology by evaluating an exemplar large bus design against the European ECE-R.66 rollover design standard. This same vehicle was similarly evaluated in a referenced study, using the finite element analysis (FEA) method. The objective of both studies was to determine a minimum weight solution for the vehicle structure. The minimum weight solution must satisfy both the minimum energy absorption requirements and the structural deformation limitations placed on the design by the ECE-R.66 standard. Both a baseline design and an optimized (minimum weight) design were evaluated in this study. The baseline design served as a reference point in determining the weight-saving potential for the vehicle. The FEA results show a weight-saving potential of 78 kg (172 lb) while the simplified, 4-bar linkage model gives a slightly heavier design with a weight-saving potential of 34 kg (77 lb), indicating that the proposed method of analysis is slightly conservative compared to the FEA method.
Finite Element Analysis (FEA) is a numerical method to find solutions to real world problems and is now commonly used for product development. Various finite element analyses are performed to validate the system performance. Many finite element codes are also available for this purpose. Now-a-days, product development not only deals with the validation of design performance, but also focuses on design optimization. Methods such as one-factor-at-a-time (OFAT) experiments are generally used in which one input factor is varied at a time and its effect on system performance is studied. Design of Experiments (DOE) is a systematic approach in which more than one input factors are purposefully varied to study their effect on system performance. Finite Element Analysis and Design of Experiments approach can be used in combination for design optimization. This paper deals with the process for design optimization that can be followed using FEA and DOE in conjunction. This methodology is explained with an example of structural optimization of rollcage having an objective to minimize the mass of rollcage structure. A finite element model is built and different simulations are performed as required for the DOE study. A screening DOE is performed to discard the unnecessary variables and then a detailed DOE study is performed. Correlations and interactions are extracted from the study to find the relationship between design variables and responses. Inferences are drawn based on these relationships and various designs are made. The optimized design is thus reached and a mass reduction of 22% is achieved.
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