Dynamic impact response of lithium-ion batteries, constitutive properties and failure model.

Use of lithium-ion batteries in transportation necessitates understanding of the cell mechanical response in case of a vehicle accident. Many researchers have access to test equipment to characterize the behavior of cells at low speeds. However, testing batteries at high speeds requires special setups that are not available for many interested parties.

Li-ion Battery Separators, Mechanical Integrity and Failure Mechanisms Leading to Soft and Hard Internal Shorts.

Separator integrity is an important factor in preventing internal short circuit in lithium-ion batteries. Local penetration tests (nail or conical punch) often produce presumably sporadic results, where in exactly similar cell and test set-ups one cell goes to thermal runaway while the other shows minimal reactions. We conducted an experimental study of the separators under mechanical loading, and discovered two distinct deformation and failure mechanisms, which could explain the difference in short circuit characteristics of otherwise similar tests.

High strength steels, stiffness of vehicle front-end structure, and risk of injury to rear seat occupants.

Previous research has shown that rear seat occupant protection has decreased over model years, and front-end stiffness is a possible factor causing this trend. In this research, the effects of a change in stiffness on protection of rear seat occupants in frontal crashes were investigated. The stiffness was adjusted by using higher strength steels (DP and TRIP), or thicker metal sheets.

Effects of vehicle front-end stiffness on rear seat dummies in NCAP and FMVSS208 tests.

Objective: This study is devoted to quantifying changes in mass and stiffness of vehicles tested by the National Highway Traffic Safety Administration (NHTSA) over the past 3 decades (model years 1982 to 2010) and understanding the effect of those changes on protection of rear seat occupants.

Methods: A total of 1179 tests were used, and the changes in their mass and stiffness versus their model year was quantified. Additionally, data from 439 dummies tested in rear seats of NHTSA's full frontal crashes were analyzed.

Reduced protection for belted occupants in rear seats relative to front seats of new model year vehicles.

Effectiveness of the rear seat in protecting occupants of different age groups in frontal crashes for 2000-2009 model years (MY) of vehicles was estimated and compared to 1990-1999 model years of vehicles. The objective was to determine the effectiveness of the rear seat compared to the front seat for various age groups in newer model year vehicles. The double paired comparison method was used to estimate relative effectiveness.

Protection of rear seat occupants in frontal crashes, controlling for occupant and crash characteristics.

In this study, the level of protection offered to rear seat occupants in frontal crashes is investigated. The Fatality Analysis Reporting System (FARS) and National Automotive Sampling System Crashworthiness Data System (NASS CDS) databases were used for the analyses. The investigation focused on: 1- estimating the fatality protection effectiveness of the rear seat position relative to the right front seat position, using the double paired comparison method, 2- evaluating the effect of control group selection method on effectiveness predictions, and 3- identifying trends in rear seat occupant protection over model years of vehicles.