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Technical Paper

Development of Methodology to Perform Dual Side Roof Strength Analysis Using Virtual Tools

Abstract The purpose of Federal Motor Vehicle Safety Standard 216 is to reduce fatalities and serious injuries when vehicle roof crushes into occupant compartment during rollover crash. Upgraded roof crush resistance standard (571.216a Standard No. 216a) requires vehicle to achieve maximum applied force of 3.0 times unloaded vehicle weight (UVW) on both driver and passenger sides of the roof. (For vehicles with gross vehicle weight rating ≤ 6,000 lb.) This paper provides an overview of current approach for dual side roof strength Finite Element Analysis (FEA) and its limitations. It also proposes a new approach based on powerful features available in virtual tools. In the current approach, passenger side loading follows driver side loading and requires two separate analyses before arriving at final assessment. In the proposed approach only one analysis suffices as driver and passenger side loadings are combined in a single analysis.
Technical Paper

Development of Exhaust Silencer for Improved Sound Quality and Optimum Back Pressure

For an automotive exhaust system, noise level and back pressure are the most important parameters for passenger comfort and engine performance respectively. The sound quality perception of the existing silencer design was unacceptable, although the back pressure measured was below the target limit. To improve the existing design, few concepts were prepared by changing the internal elements of silencer only. The design constraints were the silencer shell dimensions, volume of silencer, inlet pipe and outlet tailpipe positions, which had to be kept same as that of the existing base design. The sound quality signal replaying and synthesizing was performed to define the desired sound quality. The numerical simulation involves 3D computational fluid dynamics (CFD) with appropriate boundary condition having less numerical diffusions to predict the back pressure. The various silencer concepts developed with this preliminary analysis, was then experimentally verified with the numerical data.
Technical Paper

CAE Simulation of Door Sag/Set Using Subsystem Level Approach

The performance of door assembly is very significant for the vehicle design and door sag/set is one of the important attribute for design of door assembly. This paper provides an overview of conventional approach for door sag/set study based on door-hinge-BIW assembly (system level approach) and its limitation over new approach based on subassembly (subsystem level approach). The door sag/set simulation at system level is the most common approach adopted across auto industry. This approach evaluates only structural adequacy of door assembly system for sag load. To find key contributor for door sagging is always been time consuming task with conventional approach thus there is a delay in providing design enablers to meet the design target. New approach of door sag/set at “subsystem level” evaluates the structural stiffness contribution of individual subsystem. It support for setting up the target at subsystem level, which integrate and regulate the system level performance.
Journal Article

Influence of Vehicle Front End Design on Pedestrian Lower Leg Performance for SUV Class Vehicle

Accident statistics shows pedestrian accident fatalities as one of the important concerns globally. In view of this, new test protocols for pedestrian safety have been drafted in regulation as well as in consumer group. Also as per new ENCAP requirements, pedestrian safety assessment is used as one of the four assessment criteria's (Adult protection, child safety, pedestrian safety, safety assist) in deciding the overall vehicle safety. Hence today importance of pedestrian safety is perceived as never before in vehicle development program. Basically pedestrian safety evaluation involves subsystem level (head form, upper leg form and lower leg form) impact tests representing human body parts, at specific region on test vehicle with injury limits to decide the severity of impact. In general these injuries are governed by vehicle styling, vehicle stiffness, hard points clearances from vehicle exterior like bonnet, bumper etc.
Technical Paper

Influence of Honeycomb Cellular Meso-structure on Frontal Crash Analysis for Passenger Vehicle

Abstract Frontal collisions account for majority of car accidents. Various measures have been taken by the automotive OEMs’ with regards to passive safety. Honeycomb meso-structural inserts in the front bumper have been suggested to enhance the energy absorption of the front structure which is favorable for passive safety. This paper presents the changes in energy absorption capacity of hexagonal honeycomb structures with varying cellular geometries; under frontal impact simulations. Honeycomb cellular metamaterial structure offers many distinct advantages over homogenous materials since their effective material properties depend on both, their constituent material properties and their cell geometric configurations. The effective static mechanical properties such as; the modulus of elasticity, modulus of rigidity and Poisson’s ratio of the honeycomb cellular meso-structures are controlled by variations in their cellular geometry.