Abstract: The present study discusses about the effect of installation torque on the surface and subsurface deformations for thin walled 7075 aluminum alloy used in Aerospace applications. A FE model was constructed to predict the effect of torque induced stresses on thin walled geometry followed with an experimentation. A detailed surface analysis was performed on 7075 aluminum in terms of superficial discontinuities, residual stresses, and grain deformations. The localized strain hardening resulting from increased dislocation density and its effect on surface microhardness was further studied using EBSD and micro indentation. The predicted surface level plastic strain of .25% was further validated with grain deformations measured using optical and scanning electron microscopy.
RAMBHA-LP (Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere - Langmuir Probe) is one of the key scientific payloads onboard the Indian Space Research Organization’s (ISRO) Chandrayaan-3 mission. Its objectives were to estimate the plasma density and its variations on the near lunar surface. The probe was initially kept in a stowed condition attached to the lander. A mechanism was designed and realized to meet the functional requirement of deploying the probe at a distance of 1 meter, equivalent to the Debye length of the probe in the moon’s plasma environment. The probe deployment mechanism consists of the Titanium alloy spherical probe with a Titanium Nitride coating on its surface to achieve a constant work function, a long carbon-fiber-reinforced polymer boom, a double torsion spring, a dust-protection box, and a shape-memory alloy-based Frangibolt actuator for low-shock separation. The entire mechanism weighed less than 1.5 kilograms.
Aerospace structural components grapple with the pressing issue of high-cycle fatigue-induced micro-crack initiation, especially in high-performance alloys like Titanium and super alloys. These materials find critical use in aero-engine components, facing a challenging combination of thermo-mechanical loads and vibrations that lead to gradual dislocations and plastic strain accumulation around stress-concentrated areas. The consequential vibration or overload instances can trigger minor cracks from these plastic zones, often expanding unpredictably before detection during subsequent inspections, posing substantial risks. Effectively addressing this challenge demands the capability to anticipate the consequences of operational life and aging on these components. It necessitates assessing the likelihood of crack initiation due to observed in-flight vibration or overload events.
As the world experiences rapid climate changes due to abnormal weather, the heating functions in car seats is becoming important. The heated seat allows the driver/occupant to maintain body temperature in a cold driving environment by raising the seat temperature to the desired level. The purpose of this study is (1) to understand the trend of user interface designs across various car manufacturers and (2) to develop a method for measuring the surface temperature of a heated seat using a thermal camera. In this article, the user interface design characteristics of different car seats are summarized based on the literature survey on 100 vehicles (all vehicles are 2023 models). Specifically, temperature controller designs, control methods, controller location, temperature control stage, and price range of vehicles are reported.
In the racing world, speed is everything, and the Formula Student cars are no different. As one of the key means to improve the speed of the car, lightweight plays an important role in the racing world. The weight reduction of unsprung metal parts can not only improve the driving speed, but also effectively optimize the dynamic of the car, so the lightweight design of unsprung parts has attracted much attention. In the traditional Formula Student racing car, the hub and spoke are two independent parts, they are fixed by four hub bolts or a central locking nut, the material of these fasteners is usually steel, so it brings a lot of weight burden. In order to achieve unsprung lightweight, a new type of wheel part design of Formula Student racing car is proposed in this paper. The hub and spoke are designed as integrated aluminum alloy parts, effectively eliminating the mass of hub bolts or central locking nuts.
Abstract: Vehicle weight reduction is a popular research topic in automobile industry to achieve high efficiency and cost-effectiveness vehicles. Self-piercing rivets (SPR) are one of important joining approaches in light weight vehicle design. Numerical simulation of the riveting process could significantly boost design efficiency by reducing trial-and-error experiments. The traditional Finite Element Method (FEM) with element erosion cannot capture the large plastic deformation and complex failure behaviors in SPR process. Smoothed Particle Galerkin Method (SPG) is a genuine meshless method which is established basing on Galerkin weak form. SPG method uses a novel bond-based failure mechanism to keep the conservation of mass and momentum during material failure process. In this study, a combined FEM and Smoothed Particle Galerkin (SPG) approach was utilized to join sheet Aluminum 5754 and Cast aluminum Aural-2 using a full three-dimensional (3D) model in LS-DYNA/explicit.
The microstructure and mechanical properties of the Al-Si-Mg alloy with bulk and lattice structure produced by Laser-powder bed fusion additive manufacturing were systematically investigated. And then, the microstructure behavior of Al-Si-Mg alloys according to As-built and heat treatment was closely analyzed. Firstly, through grain size analysis, the cause of mechanical properties higher than casting materials and similar to forging materials could be analyzed. Secondly, mechanical changes according to the Mg2Si reinforced phase and cell-wall morphology after heat treatment were investigated. The Al-Si-Mg bulk and lattice structures are composed of a cell structure consisting of α-Al and eutectic Si. With heat treatment, needle-shape Mg2Si precipitates in the α-Al matrix. Simultaneously, collapse of the cell-wall morphology occurs.
With the advancement of intelligent driving technology, the driving comfort of autonomous vehicles has garnered significant attention. Under highly automated driving conditions, the driver does not need to engage in driving tasks. Since the automation of vehicles will reach a considerable level,the driver inside the vehicle becomes a passenger, and now the study of the passenger experience in automated driving vehicles has become an important research topic. To investigate the effects of automatic driving on passengers' riding experience in vehicle platooning scenarios, the study conducted real vehicle experiments with six participants. The study measured the subjective perception scores, eye movement, and electrocardiogram signals of passengers in the front passenger seat under different vehicle speeds, distances, and driving modes. The results of the statistical analysis show that vehicle speed has the most significant impact on passenger perception.
Aluminum alloy has become an indispensable part of the automotive industry because of its excellent mechanical properties such as lightweight, high strength, high reliability, maintainability, and low cost. Aluminum alloy is used in automobiles, such as engine blocks, cylinder heads, intake manifolds, brake components, and fuel tanks. Fatigue and fracture are the main reasons for its engineering failure. Surface strengthening techniques, such as ultrasonic shot peening (USP), are often used to improve the fatigue resistance of aluminum alloys. This article expounds on the working principle of ultrasonic shot peening and elucidates the influence of USP process parameters on the surface characteristics of aluminum alloy. Experimental results observed the effects of USP parameters on surface properties such as surface roughness, microhardness, and surface morphology.
The author has developed UV based photocatalytic air purification system (Mathur, 2021, 2023) that can eliminate all pathogens from the cabin air including COVID-19. In this study, the focus is to determine the risk of infection due to pathogens/germs in the cabin of an automobile. Author has determined the risk of infection by using Wells-Riley model and the conducted CFD analysis to determine propagation of virus in cabin.: 1. Cabin Volume & Number of Occupants (Wells-Riley Model in OSA mode): (i) Cabin volume from: Small Sedan, Large Sedan and a SUV; with 4 occupants (males & females); Number of infector 1; Air flowrate (m3/min); (ii) A 15-seater minibus - with 10 occupants(males); Number of infectors 1 & 2; Air flowrate (m3/min) 2.
Finite element (FE) seat models are typically validated using the FE models of anthropomorphic test devices (ATDs) due to geometric and material similarity with their physical counterparts. One of the key aspects of seat validation is to match the occupant loading of the seatback via optimizing the foam material property. The validated seats are then used for evaluating the biofidelity of FE human body models (HBMs). This study compared the responses of the thorax and pelvis of the GHBMC M50-O using two different foam materials – OPT and REF – in a high-speed rear facing frontal impact scenario. The OPT foam was optimized using a Hybrid III ATD FE model, while the REF foam was a reference foam material from literature with a late densification phase. The simulations were performed using the LS-DYNA software. The T-spine accelerations increased with the use of REF as compared to OPT, trending towards the corresponding PMHS responses.
Fracture characterization of automotive metals under simple shear deformation is critical for the calibration of advanced fracture models employed in forming and crash simulations. Great strides in shear fracture characterization have been made over the past decade with several novel geometries proposed. However, in-plane shear tests of high ductility materials have proved challenging since the edge fails first in uniaxial tension before the shear fracture limit is reached in the center of the sample. Although through-thickness machining is undesirable, particularly for extrusions and castings, it appears required to promote higher strains within the shear zone to avoid edge cracking in materials where the shear fracture limit significantly exceeds that of uniaxial tension. The objective of the present study is to adapt existing in-plane shear geometries, which have otherwise been successful for many automotive materials, to have a local shear zone with a reduced thickness.
At the dawn of battery electric vehicles (BEVs), protection of automotive battery systems as well as passengers, especially from severe side impact, has become one of the latest and most challenging topics in the BEV crashworthiness designs. Accordingly, two material-selection concepts are being justified by the automotive industry: either heavy-gauge extruded aluminum alloys or light-gauge advanced high-strength steels (AHSSs) shall be the optimal materials to fabricate the reinforcement structures to satisfy both the safety and lightweight requirements. In the meantime, such a justification also motivated an ongoing C-STARTM (Cliffs Steel Tube as Reinforcement) Protection project, in which the all-AHSS(s) reinforcement beams, essentially a series of modularized steel tube assemblies, were demonstrated both experimentally and virtually to be more cost-efficient, sustainable, design-flexible, and manufacturable than the equivalent extruded aluminum alloy beams.
Upcoming, increasingly stringent greenhouse gas as well as emission limits demand for powertrain electrification throughout all vehicle applications. Increasing complexity of electrified powertrain architectures require an overall system approach combining modular component technology with integration and industrialization requirements when heading for further significant efficiency optimization. At the same time focus on reduced development time, product cost and minimized additional investment demand reuse of current production, machining, and assembly facilities as far as possible. Up to date additive manufacturing (AM) is an established prototype component, as well as tooling technology in the powertrain development process, accelerating procurement time and cost, as well as allowing to validate a significantly increased number of variants. The production applications of optimized, dedicated AM-based component design however are still limited.
This research focuses on the commercial 6111 aluminum alloy as the subject of investigation. By designing tensile specimens with the same characteristic dimensions but varying fillet radii, the effects of fillet radius on the tensile properties and stress concentration effects of the aluminum alloy were studied through tensile testing and digital image correlation techniques. The results demonstrate that with an increase in fillet radius, the failure strength and stress distribution of the aluminum alloy specimens have both undergone alteration. This phenomenon can be attributed to the reduction of stress concentration at the fillet due to the larger fillet radius. Further verification through digital image correlation reaffirms that samples with a fillet radius of 10mm exhibit notable stress concentration effects at the fillet, while specimens with a fillet radius increased to 40mm display uniform plastic deformation across the parallel section.
Ergonomics plays an important role in automobile design to achieve optimal compatibility between occupants and vehicle components. The overall goal is to ensure that the vehicle design accommodates the target customer group, who come in varied sizes, preferences and tastes. Headroom is one such metric that not only influences accommodation rate but also conveys a visual perception on how spacious the vehicle is. An adequate headroom is necessary for a good seating comfort and a relaxed driving experience. Headroom is intensely discussed in magazine tests and is a key deciding factor in purchase of a car. SAE J1100 defines a set of measurements and standard procedures for motor vehicle dimensions. H61, W27, W35, H35 and W38 are some of the standard dimensions that relate to headroom and head clearances. While developing the vehicle architecture in the early design phase, it is customary to specify targets for various ergonomic attributes and arrive at the above-mentioned dimensions.
In today's automotive industry, the preference for suspension systems in high-end passenger vehicles is shifting away from conventional MacPherson or double wishbone setups and toward advanced double wishbones with split-type control arms or multi-link suspensions. This shift not only enhances the ride and handling experience but also introduces greater design complexities. This paper explains the design limitations of the conventional double wishbone front suspension (with 2 ball joints) and the opportunities presented by advanced double wishbone suspension designs, including split-type lower control arms (with 3 ball joints) and double split-type control arms (with 4 ball joints). Replacing the rigid link of the conventional double wishbone suspension with a four-bar mechanism in the case of split-type control arm wishbone suspension significantly alters the behavior of the King-pin axis, leading to consequential effects on steering and suspension parameters.
The Large Omnidirectional Child (LODC) developed by the National Highway Traffic Safety Administration (NHTSA) has an improved biofidelity over the currently available Hybrid III 10-year-old (HIII-10C) Anthropomorphic Test Device (ATD). The LODC design incorporates enhancements to subassemblies, such as the head, a redesigned HIII-10C head with pediatric mass properties, and the neck, which produces head lag with Z-axis rotation at the atlanto-occipital joint replicating the observations made from the human specimens. The LODC also features a flexible thoracic spine, a multi-point thoracic deflection measurement system, skeletal anthropometry that simulates a child's sitting posture, and an abdomen that can measure belt loading directly. This study presents the development and validation of a dynamic nonlinear finite element model of the complete LODC dummy. Based on the three-dimensional CAD model, Hypermesh was used to generate a mesh of the finite element (FE) LODC model.