Windshield Wiper System life improvement using overstress testing to determine the product weak point

An overstress testing methodology has been developed by Valeo Wiper Systems and followed in order to decrease the project validation time and determine the wiper system mechanism reliability. This methodology could be followed to analyze new projects, as well as quality problems, improvements ideas and to test new materials. The stress levels were calculated by using the cumulative fatigue laws. During the accelerated test the samples were tested until some component or function fail. In order to have representative results, all the failure modes shall be compared with the FEA (Finite Element Analysis) performed with the drawings. The main objective was to verify the possibilities of reliability increasing to have a robust product, and it was necessary to validate the product weak point. The reliability level is determined by using the Life Data Analysis methodology, acquiring the number of the wiping cycles performed until the failure. Comparing the failure point with the FEA it was evidenced that the accelerated test represents the product usage profile. Some preventive actions in the production line have been reached and in this example the time until the failure increased from 1.5 million to 2.5 million. Nowadays the customers are requesting to increase the warranty period from 1 to 3 years, and with this modification it is possible to certify that the product will keep the quality during this time.