Browse Publications Technical Papers 2018-01-0112

Predicting Aging due to Thermal Oxidation and Determining Service Limit for Nylon 66 Fiber in Vehicles Exposed to Actual Weather Conditions 2018-01-0112

The guarantee of long-term reliability of cars is becoming increasingly important in society. It is extremely important to confirm whether the condition of the accelerated deterioration test (for evaluating long-term reliability) is reasonable with respect to recent use environment conditions.
In this paper, we propose how to promote degradation test conditions to guarantee the function of parts (resin materials of interior parts) exposed over a long period of time to a severe temperature environment inside the car. Heat-resisting grade nylon 66 fiber (hereinafter referred to as H-PA 66), which is a constituent material of parts requiring long-term reliability, was used as a specific resin material.
High-temperature accelerated deterioration test of H-PA 66 fiber was carried out to obtain the time (hereinafter referred to as 90% strength time,) during which the tensile strength retention rate decreased to 90%. The relationship between this high temperature accelerated deterioration temperature and 90% intensity time could be expressed by the Arrhenius equation. The acceleration rate of deterioration was determined from the Arrhenius plot of this equation. At the same time, we propose DOE (Design of Engineering) graph which can judge deterioration by expressing accelerated deterioration temperature on the vertical axis and accelerated deterioration time on the horizontal axis.
We predicted deterioration after 15 years from the temperature history of the actual environment obtained by the exposure test. Moreover, reasonable promotion deterioration condition without excess or deficiency in the case of 15 year guarantee was sought. The DOE graph (capable of expressing the relationship between the actual use environment and accelerated deterioration test condition) improves the accuracy and reliability of the accelerated deterioration condition.


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