Stress Analysis
Evaluate each listed part in its intended application, and record the engineering data required to determine the application factors in the relevant failure rate model.
Example
The failure rate model for a resistor is as follows:
Where:
λp= The predicted failure rate of the particular component (in failures/106 component operating hours) under stated environmental, temperature and electrical stress conditions.
λB= The operational base failure rate of the component.
KE= The environmental factor for the operational environment of the component.
KS= The temperature and electrical stress factor for the component.
To determine KS, the following engineering data is required:
◦ The temperature in which the resistor is required to operate.
◦ The rated power of the resistor.
◦ The mean operating power of the resistor in its intended application.
The stress ratio is:
This ratio and the temperature in which the resistor is required to operate enable the appropriate value to be determined from the tables in Data Tables.