International Journal of Vehicle Structures and Systems

Rasoul Moradi ¹, Rajarshi Setpally ¹, Hamid M. Lankarani ¹

Affiliations
1 Department of Mechanical Engineering, Wichita State University, Wichita, Kansas, US

Abstract

In car/large truck collisions, the size, weight, and stiffness mismatch results in a much larger structural deformation of the car compared to that of the truck, and larger potential for car occupants injuries. This is further aggravated when the passenger vehicle trends beneath the rear or side of the taller truck. In the US, under-ride guards are required only for the rears of large trucks, although the review of fatal truck-car crashes in the NCSS/CDS indicates that fatal under-ride crashes involving the sides of large trucks are almost as common as fatal rear under-ride crashes. A methodology using validated finite element models of a passenger car and a truck is utilized in this study to quantify the influence of a side guard attached to a large truck in reducing the intrusion of the car and thus reducing the injury sustained by the occupants of a car in a side crash. A formulation is proposed based on a normalized passenger compartment intrusion and its relation to the occupant injury potential. The transmitted deceleration severity and the occupant compartment intrusion are evaluated for the car impacting a rigid under-ride guard. A NHTSA under-ride test is simulated first for model validation. Once model validation is conducted for a specific guard design, further simulations are conducted at the speed range of 30 to 50 mph and for 90 and 45-degree impact angles. The results from a parametric study are used to identify the critical guard height resulting in severe cabin deceleration and compartment intrusion of the small car. This study quantifies the vulnerability of car occupants in truck side under-ride crashes and the effectiveness of side guard at different ground heights in reducing the injury potential to car occupants.

Keywords

Automotive Crashworthiness, Injury Potential, Passenger Compartment Intrusion, Truck Side Under-Ride Guard, Side Impact.

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Prasannakumar S. Bhonge ¹, Hamid M. Lankarani ¹

Affiliations
1 Wichita State University, Wichita, Kansas, US

Abstract

Finite element analysis (FEA) has become a part of new development in automotive as well as in aircraft seating industries. The goal of the FEA in product development is not only to design but to substantiate the certification tests or possibly replace the certification tests. The case of a certification by substantiation tests increases the necessity of validation of the Finite Element (FE) model. In the aircraft industry, the seating Advisory Circular (AC) 20-146 specifies a methodology for the dynamic seat, Certification By Analysis, for use in the Parts 23, 25, 27 and 29 airplanes and rotorcraft. In FE modeling of typically nonlinear environments such as the aircraft dynamic seat simulations, input parameters such as material model, element type, time step scale factor, element length, material model etc. play a vital role in the accuracy of the results. Selecting appropriate material models and other parameters leads to improved accuracy in the FE model and hence to validation with the experimental test results. The purpose of this study is to fine-tune non-linear FEA methodology for aircraft seat certification using component level testing and validation. For this purpose, the effects of input parameters such as the material model, element length, and time step scale factor are evaluated using component test-FE simulation on static tension test on aluminum, high speed load-deflection test on seat cushion and belt pull test. Verification of FE input parameters is determined in each case. Appropriate input variables are selected and provided to an aircraft seat FEA case study and validated against sled test results to demonstrate the validity of the finite element models.

Keywords

Aircraft Crashworthiness, Certification by Analysis, Finite Element Analysis, Seat Certification, Substantiation.

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