Pradeep Mohan

Performance Evaluation of Low-Tension Three-Strand Cable Median Barriers

The primary purpose of longitudinal safety barriers, such as cable barriers, is to contain or redirect errant vehicles that depart the roadway and thereby keep them from entering opposing travel lanes or encountering terrain features and roadside objects that may cause severe impacts. In this study, finite element analysis, vehicle dynamics analysis, and full-scale crash testing were performed to study the effects of sloped terrain on the safety performance of cable median barriers. A detailed finite element model of a three-strand cable barrier was developed and validated against a previously conducted full-scale crash test. The full-scale crash test and simulation were set up for an impact of the cable barrier with a 2,000-kg (4,400-lb) pickup truck at an angle of 25° and an initial velocity of 100 km/h (62 mph). This setup is in accordance with NCHRP Report 350 guidelines for Test Level 3 safety performance. With this model, computer simulations were performed to assess the performance of the barrier under different impact scenarios and with different terrain profiles. Vehicle dynamics analyses were also conducted to compute the trajectory and dynamics of the vehicle as it crossed the sloped terrain and struck the cable median barrier. On completion of the computer simulation analyses, full-scale crash testing was performed to validate the results.

Validation of a Single Unit Truck Model for Roadside Hardware Impact

The objective of this research is to validate the Finite Element (FE) model of a Ford F800 Single Unit Truck (SUT). The FE model of the SUT was developed at the FHWA/NHTSA National Crash Analysis Centre (NCAC) at the George Washington University (GWU). In this study, the characteristics of the SUT model were investigated and several modifications were incorporated in the model to accurately simulate its interaction with roadside safety hardware. A full-scale crash test of the Ford F800 SUT impacting an F-shape Portable Concrete Barrier (PCB) was conducted at The Federal HighWay Administrations (FHWA) Federal Outdoor Impact Laboratory (FOIL) and used in the validation. The response of any vehicle impacting a PCB is primarily governed by the mass and suspension characteristics of the vehicle. Detailed methods for modelling the trucks suspension components are discussed.

Crashworthiness and Numerical Analysis of Composite Inserts in Vehicle Structure

The objective of this research is to understand the crashworthiness performance of composite inserts in vehicle structure and to improve the numerical model of steel-composite combined structure for providing better prediction in the design process of composite inserts. A simplified steel-composite combined beam structure is used for three-point bending tests. Epoxy-based structural foam and 33% short glass fiber reinforced nylon composite insert are considered as composite fillers in empty sections of double hat-type steel beam structure. Four cases based on the different combination of composite materials are considered. In the series of physical three-point bending tests, the force-displacement (F-D) curves and material behaviors are investigated. The test results show that the composite insert greatly contributes to improve the crashworthiness of beam structure as well as to reduce the vehicle weight. Especially, the adhesive failure of structural foam and the brittle fracture mode of composite insert are greatly influential to the resistance force level in the three-point bending test. In the numerical study, a concern is to build a practical FE model, which can be used in full-scale vehicle crash simulation. The parametric study shows that parameters related to material and contact types are critical to simulate the adhesive failure of structural foam and the brittle fracture of composite insert. The final simulation results show good agreement with the physical tests. Language: en