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Technical Paper

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

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

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

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

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

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.
Journal Article

A Study into the Mechanical Behavior of Adhesively-Bonded Jute Fiber-Reinforced Composite

Rapid progress in the interdisciplinary field of automotive engineering and the pressing need for an environmental friendly alternative to metal and synthetic fiber-reinforced composites for vehicle structure have triggered recent research in the field of natural fiber-based composites. Their potential advantages are attributed to their light weight, low cost and biodegradability. However, their usage in present day automotive systems is restricted due a lower magnitude range of mechanical properties and limited study in this area. In contrast to mechanical joints, the adhesively bonded joints aid in reducing stress concentration, joining of dissimilar materials, corrosion prevention, weight reduction and a smoother finish. Thus, in the present study, failure load, and mean shear stress of single lap shear and double lap shear joints as a function of joint overlap length, are evaluated using a two part epoxy adhesive made by Huntsman.
Technical Paper

Performance of Lightweight Materials for Vehicle Interior Trim Subject to Monotonic Loading and Low Velocity Impact

The usage of lightweight materials such as plastics and their derivatives continues to increase in automobiles driven by the urgency for weight reduction. For structural performance, body components such as A-pillar or B-pillar trim, instrument panel, etc. have to meet various requirements including resistance to penetration and energy absorption capability under impact indentation. A range of plain and reinforced thermoplastics and thermosetting plastics has been considered in the present study in the form of plates which are subject to low velocity perforation in a drop-weight impact testing set-up with a rigid cylindrical indenter fitted to a tup. The tested plates are made of polypropylene (PP), nanoclay-reinforced PP of various percentages of nanoclay content, wood-PP composites of different volume fractions of wood fiber, a jute-polyester composite, and a hybrid jute-polyester reinforced with steel.
Journal Article

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

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

An Assessment of Load Cell- and Accelerometer-Based Responses in a Simulated Impact Test

Load cells and accelerometers are commonly used sensors for capturing impact responses. The basic objective of the present study is to assess the accuracy of responses recorded by the said transducers when these are mounted on a moving impactor. In the present work, evaluation of the responses obtained from a drop-weight impact testing set-up for an axially loaded specimen has been carried out with the aid of an equivalent lumped parameter model (LPM) of the set-up. In this idealization, a test component such as a steel double hat section subjected to axial impact load is represented with a nonlinear spring. Both the load cell and the accelerometer are represented with linear springs, while the impactor comprising a hammer and a main body with the load cell in between are modelled as rigid masses. An experimentally obtained force-displacement response is assumed to be a true behavior of a specimen.
Journal Article

Efficient Approximate Methods for Predicting Behaviors of Steel Hat Sections Under Axial Impact Loading

Hat sections made of steel are frequently encountered in automotive body structural components such as front rails. These components can absorb significant amount of impact energy during collisions thereby protecting occupants of vehicles from severe injury. In the initial phase of vehicle design, it will be prudent to incorporate the sectional details of such a component based on an engineering target such as peak load, mean load, energy absorption, or total crush, or a combination of these parameters. Such a goal can be accomplished if efficient and reliable data-based models are available for predicting the performance of a section of given geometry as alternatives to time-consuming and detailed engineering analysis typically based on the explicit finite element method.
Technical Paper

Energy-Based Criteria for Crashworthiness Design of Aluminum Intensive Space Frame Vehicles

Space frame type vehicle construction with extruded aluminum members holds promise in terms of desirable vibration-resistant and crashworthiness characteristics. Efficient design of such vehicles for superior frontal crash performance can be accomplished by judicious use of validated finite element and lumped parameter modeling and analysis. However, design iterations can be reduced considerably by employing energy-absorption targets for key members such as front rails in arriving at the initial design concept. For the NCAP (New Car Assessment Program) test procedure, a constraint is laid in terms of achieving a desirable level of vehicle peak deceleration for occupant safety. Using the information obtained through analysis, a numerical target can be set for energy to be absorbed by front rails. For this energy target, a new relationship is then derived which can be utilized for preliminary design of rail cross-section and material strength.