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Technical Paper

Effect of Strain Rate on Mechanical Responses of Jute-Polyester Composites

2017-03-28
2017-01-1467
There has been a keen interest in recent times on implementation of lightweight materials in vehicles to bring down the unladen weight of a vehicle for enhancing fuel efficiency. Fiber-reinforced composites comprise a class of such materials. As sustainability is also a preoccupation of current product development engineers including vehicle designers, bio-composites based on natural fibers are receiving a special attention. Keeping these motivations of lower effective density, environment friendliness and occupational safety in mind, woven jute fabric based composites have been recently studied as potential alternatives to glass fiber composites for structural applications in automobiles. In the past, mechanical characterization of jute-polyester composites were restricted to obtaining their stress-strain behaviors under quasi-static conditions.
Technical Paper

Prediction of the Behaviors of Adhesively Bonded Steel Hat Section Components under Axial Impact Loading

2017-03-28
2017-01-1461
Adhesively bonded steel hat section components have been experimentally studied in the past as a potential alternative to traditional hat section components with spot-welded flanges. One of the concerns with such components has been their performance under axial impact loading as adhesive is far more brittle as compared to a spot weld. However, recent drop-weight impact tests have shown that the energy absorption capabilities of adhesively bonded steel hat sections are competitive with respect to geometrically similar spot-welded specimens. Although flange separation may take place in the case of a specimen employing a rubber toughened epoxy adhesive, the failure would have taken place post progressive buckling and absorption of impact energy.
Technical Paper

A 3D Simulation Methodology for Predicting the Effects of Blasts on a Vehicle Body

2019-04-02
2019-01-1033
Triggered explosions are increasingly becoming common in the world today leading to the loss of precious lives under the most unexpected circumstances. In most scenarios, ordinary citizens are the targets of such attacks, making it essential to design countermeasures in open areas as well as in mobility systems to minimize the destructive effects of such explosive-induced blasts. It would be rather difficult and to an extent risky to carry out physical experiments mimicking blasts in real world scenarios. In terms of mechanics, the problem is essentially one of fluid-structure interaction in which pressure waves in the surrounding air are generated by detonating an explosive charge which then have the potential to cause severe damage to any obstacle on the path of these high-energy waves.
Technical Paper

Behavior of Adhesively Bonded Steel Double-Hat Section Components under Lateral Impact Loading

2018-04-03
2018-01-1447
Recent experimental studies on the behavior of adhesively-bonded steel double-hat section components under axial impact loading have produced encouraging results in terms of load-displacement response and energy absorption when compared to traditional spot-welded hat- sections. However, it appears that extremely limited study has been carried out on the behavior of such components under transverse impact loading keeping in mind applications such as automotive body structures subject to lateral/side impact. In the present work, lateral impact studies have been carried out in a drop-weight test set-up on adhesively-bonded steel double-hat section components and the performance of such components has been compared against their conventional spot-welded and hybrid counterparts. It is clarified that hybrid components in the present context refer to adhesively-bonded hat-sections with a few spot welds only aimed at preventing catastrophic flange separations.
Technical Paper

A Study on Combined Effects of Road Roughness, Vehicle Velocity and Sitting Occupancies on Multi-Occupant Vehicle Ride Comfort Assessment

2017-03-28
2017-01-0409
It is recognized that there is a dearth of studies that provide a comprehensive understanding of vehicle-occupant system dynamics for various road conditions, sitting occupancies and vehicle velocities. In the current work, an in-house-developed 50 degree-of-freedom (DOF) multi-occupant vehicle model is employed to obtain the vehicle and occupant biodynamic responses for various cases of vehicle velocities and road roughness. The model is solved using MATLAB scripts and library functions. Random road profiles of Classes A, B, C and D are generated based on PSDs (Power Spectral Densities) of spatial and angular frequencies given in the manual ISO 8608. A study is then performed on vehicle and occupant dynamic responses for various combinations of sitting occupancies, velocities and road profiles. The results obtained underscore the need for considering sitting occupancies in addition to velocity and road profile for assessment of ride comfort for a vehicle.
Technical Paper

Introduction of Two New Pediatric Finite Element Models for Pedestrian and Occupant Protections

2016-04-05
2016-01-1492
To help predict the injury responses of child pedestrians and occupants in traffic incidents, finite element (FE) modeling has become a common research tool. Until now, there was no whole-body FE model for 10-year-old (10 YO) children. This paper introduces the development of two 10 YO whole-body pediatric FE models (named CHARM-10) with a standing posture to represent a pedestrian and a seated posture to represent an occupant with sufficient anatomic details. The geometric data was obtained from medical images and the key dimensions were compared to literature data. Component-level sub-models were built and validated against experimental results of post mortem human subjects (PMHS). Most of these studies have been mostly published previously and briefly summarized in this paper. For the current study, focus was put on the late stage model development.
Technical Paper

An Alternative Approach for Formulation of a Crushable PU Foam Considering its Behavior under Compressive Loads

2015-04-14
2015-01-1483
Rigid polyurethane (PU) foam finds wide applications as a lightweight material in impact safety design such as improving occupant safety in vehicle crashes. The two principal reacting compounds for formulating such foam are variants of polyol and isocyanate. In the present study, an alternative mechanical engineering-based approach for determining, with confidence, the desirable ratio of reacting compounds for formulation of a rigid/crushable PU foam for mechanical applications is demonstrated. According to the present approach, PU foam samples are prepared by varying the mixing ratio over a wide range. The desirable mixing ratio is shown to be the one that optimizes key mechanical properties under compression such as total absorbed energy, specific absorbed energy and energy absorption efficiency.
Journal Article

A Comparison of the Behaviors of Steel and GFRP Hat-Section Components under Axial Quasi-Static and Impact Loading

2015-04-14
2015-01-1482
Hat-sections, single and double, made of steel are frequently encountered in automotive body structural components. These components play a significant role in terms of impact energy absorption during vehicle crashes thereby protecting occupants of vehicles from severe injury. However, with the need for higher fuel economy and for compliance to stringent emission norms, auto manufacturers are looking for means to continually reduce vehicle body weight either by employing lighter materials like aluminum and fiber-reinforced plastics, or by using higher strength steel with reduced gages, or by combinations of these approaches. Unlike steel hat-sections which have been extensively reported in published literature, the axial crushing behavior of hat-sections made of fiber-reinforced composites may not have been adequately probed.
Technical Paper

Use of Truncated Finite Element Modeling for Efficient Design Optimization of an Automotive Front End Structure

2015-04-14
2015-01-0496
The present work is concerned with the objective of multi disciplinary design optimization (MDO) of an automotive front end structure using truncated finite element model. A truncated finite element model of a real world vehicle is developed and its efficacy for use in design optimization is demonstrated. The main goal adopted here is minimizing the weight of the front end structure meeting NVH, durability and crash safety targets. Using the Response Surface Method (RSM) and the Design Of Experiments (DOE) technique, second order polynomial response surfaces are generated for prediction of the structural performance parameters such as lowest modal frequency, fatigue life, and peak deceleration value.
Technical Paper

Behavior of Adhesively Bonded Steel Double Hat-Section Components under Axial Quasi-Static and Impact Loading

2016-04-05
2016-01-0395
An attractive strategy for joining metallic as well as non-metallic substrates through adhesive bonding. This technique of joining also offers the functionality for joining dissimilar materials. However, doubts are often expressed on the ability of such joints to perform on par with other mechanical fastening methodologies such as welding, riveting, etc. In the current study, adhesively-bonded single lap shear (SLS), double lap shear (DLS) and T-peel joints are studied initially under quasi-static loading using substrates made of a grade of mild steel and an epoxy-based adhesive of a renowned make (Huntsman). Additionally, single lap shear joints comprised of a single spot weld are tested under quasi-static loading. The shear strengths of adhesively-bonded SLS joints and spot-welded SLS joints are found to be similar. An important consideration in the deployment of adhesively bonded joints in automotive body structures would be the performance of such joints under impact loading.
Technical Paper

An Optimization Study of Occupant Restraint System for Different BMI Senior Women in Vehicle Frontal Impact

2020-04-14
2020-01-0981
Accident statistics have shown that older and obese occupants are less adaptable to existing vehicle occupant restraint systems than ordinary middle-aged male occupants, and tend to have higher risk of death and injury in vehicle crashes.However, the current research on the mechanism of injury in vehicle frontal impact for aging and obese occupants is scarce. This paper mainly focuses on the optimization design method of occupant constraint system parameters for specific body type characteristics. The damage attributes of vehicle crash on elderly female with different BMI (body mass index) was analyzed. The design variables in the constraint system were screened for DOE analysis. We selected five parameters for optimization, namely the force limiter force limit value of the seat belt, the pretensioner preload of the seat belt, the preload time of the seat belt, the ignition time of the airbag, the proportionality coefficient of the mass flow rate of the airbag.
Technical Paper

A primary study on the restraint system of self-driving car

2020-04-14
2020-01-1333
Due to the variation of compartment design and occupant’s postures in the self-driving car, there is a new and major challenge for occupant protection. In particular, the studies on occupant restraint systems used in the self-driving car has significantly delayed compared to the development of the autonomous technologies. In this paper, a numerical study was conducted to investigate the protective effects of the mainstream restraint systems (3-points belt with airbag or 4-points belt with airbag) on the driver in three different scenarios (driving with a seat angle of 110°, half-reclining resting with a seat angle of 135°, and reclining resting with a seat angle of 160°) . It can be found that in the simulation results: 1. All the restraint systems are capable of providing effective protection for the driving driver and the restraint system with 4-points belt has advantages due to its better protective effect on the occupant thorax; 2.
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