This Recommended Practice describes a standard process for Reliability Physics Analysis (RPA1) for Electrical, Electronic, and Electromechanical (EEE) equipment, modules, and components used in the Automotive, Aerospace, Defense and other High-Performance (AADHP) industries
The AADHP industries are characterized by long lifetimes, rugged operating environments, and stringent safety and reliability requirements. It is critical to address these requirements by
RPA is a modern, science-based approach for reliability optimization, failure risk assessments and risk elimination achieved through the use of Computer Aided Engineering (CAE) durability simulation of EEE devices. RPA durability simulation combines stress analysis of usage and environmental conditions with EEE failure mechanism models produced and validated relevant research and data.
RPA leverages scientific understanding of the mechanisms that cause failure in EEE equipment, modules, and components; to assess their capability to perform their intended functions safely and reliably throughout their lifetimes. RPA is based on data acquired from relevant research, field experience and/or credible, relevant testing. It employs Finite Element Analysis (FEA) to quantify the relevant stresses on an item, and simulate its performance in the expected operating environments. RPA also uses mathematical modeling to quantify the factors that accelerate failures, and estimate times-to-failure risks over the EEE equipment’s expected lifetimes. RPA is facilitated by the use of CAE methods to perform a durability simulation that identifies reliability performance or failure risk over the service life of EEE equipment.
While RPA is technically complex, its implementation has become practical through ongoing advancements and availability of computing power, and the ease-of-use provided by CAE application programs that has facilitated its use. As its use proliferates, RPA is being conducted in a variety of ways; and its results are being reported and used in variety of ways; and the potential for confusion is increasing. To satisfy their needs for safety and reliability, the AADHP industries propose this recommended practice document to develop industry consensus on the best “standard” process for RPA. This consensus is broadened by cooperation among industries, including automotive and aerospace, to develop, maintain, and apply the RPA process to be described in this document.
The basic steps and models of the RPA process are applicable to EEE technologies used in all AADHP industries, however, their implementation may vary according to products, operating conditions durability service lifetimes, and environments. Therefore, this document describes the baseline RPA process, and a series of appendices or other sub-documents will describe its implementation in a range of specific circumstances.This document is not intended to be a mandatory list of tasks to be performed, tests to be conducted, or data to be reported, for every application in every program. Nor is it intended to mandate sophisticated high-end CAE simulations for situations when more basic calculation techniques will suffice. This document lists the basic steps to be taken to produce a credible RPA, whose results can be applied in a variety of ways to produce functional, safe, and reliable products, which can be designed, developed, validated, and, if necessary, certified effectively and efficiently.
This document is applicable to all hardware components of an EEE system. It is applicable to failure mechanisms that result from degradation of materials or accumulated damage to components, that impact the functional outputs of an EEE system based on the material science principle of stress driven damage accumulation in materials. It is not applicable to failures caused by design errors or misuse of the system; nor is it applicable to software.1 RPA is also called physics-of-failure (PoF) analysis, but RPA is used here because it more accurately represents the intent of the process.