Vehicle Reliability Estimation Model for Concept Vehicle Target Setting and Identification of Critical Parameters Influencing System Reliability 2010-32-0068

Reliability has been a complicated domain of vehicle engineering, basically due to the quantum of the authentic data required, and variability of parameters that make real contributions to the subject. Reliability of a vehicle in very generic terms, is not only its functional worthiness and consistency, but also its probability to perform satisfactorily within the intended design life for a particular production batch, application domain, operation duty and customer use.

Commercial vehicle industry is driven by returns that a vehicle gives, on the investments made, which depend on parameters like minimum turnaround time, lesser breakdowns, optimized maintenance interval and cost of operation etc. Severe operating conditions, regular customer abuse and higher expectations from products (as expected by Indian customer-base) demand a need to deliver more robust and reliable products. Commercial vehicle industry in India finds reliability as one of the most interesting subjects to work-on as it has significant impact on the warranty cost (for manufacturer) and on product uptime (for customer), both being the key parameters that defines, the success of the product.

This triggers the need for designers to set targets for reliability at concept phase of vehicle design, which could predict the reliability concerns related to a particular model class for a specific operational duty (load and road). The subject had always been of ambiguity to vehicle designers, basically due to lack or anonymity of data, which could help in estimating reliability and also due to the variability in factors that influence it in one way or the other.

Through this paper, an effort has been made to give simple perspective to reliability (from end user stand point) and develop a ‘Vehicle Reliability Estimation Model’ to understand competition reliability performance for specific model class, operational duty and thereby to set concept vehicle target. Focus is on, to conceptualize a reliability estimation model, which could be used to predict reliability of complex automotive systems like small engines, power-trains, steering system, braking system etc. as individual systems and also to apply the same on vehicle as a whole from analytical and holistic standpoint. The input data set is basically collected from logs made on reliability test vehicles, which include competition benchmarks that have been operated under defined design and market usage conditions (road and load).

The scope of work involves defining vehicle reliability from end user standpoint, understanding modes of operational failure, analyzing failure data, developing logical inferences from statistical sample set, derivation of critical parameters influencing reliability, estimation of vehicle reliability index followed by target setting for concept vehicle. Vehicle Reliability Estimation Model (VREM) will help the original equipment manufacturers (OEM) in improving customer satisfaction, building brand value, reliability-related cost cut down, reduce campaign recalls by use of a proactive design methodology, predicting reliability related concerns that can be recognized, appreciated and improved at early stages of vehicle and system design.