The Validation Process - One Key Element of Reliability Management 2005-01-1778
Due to increasing durability requirements driven by engine emission regulations such as Euro 5 and US'07, the reliability of the engine cooling equipment, especially of charge-air-to-air-cooler (CAC), has to be increased as well. Behr is using reliability management in order to meet these requirements.
“Reliability” is defined as the fulfillment of quality requirements over the life cycle and under specific application conditions. At Behr, the reliability management is organized as a “House of Reliability” (HOR). The mission profile includes up-to-date customer requirements, loads and statistical experience from the field and helps to create relevant test specifications for the validation testing. Validation is one key element of the HOR. If the test specifications are not connected to the field, the testing will not lead to a reliable product and to customer satisfaction.
The process of gathering load collectives for mission profiles is therefore very important. With a linear damage accumulation theory such as the linear Miner's Rule, the measured collective can be transferred into an equivalent test which creates the same damage.
In order to reduce the required number of test samples an adequate test strategy has to be applied. With Weibull statistics the necessary increase of load cycles for a reduced set of test specimens can be calculated.
In order to learn as much as possible from today's products, methods of field statistics, e.g. Weibull, is used to describe the reliability of existing products.
Since testing with serial production parts is only possible very late in the development process, simulation of validation tests is needed to improve the design very early in the process. Behr uses numerical analysis methods to simulate the main validation tests.