A mechanical design method to ensure that machinery and its components meet the given reliability. Including prediction, distribution, technical design, evaluation, etc. The so-called reliability refers to the ability of the product to complete the specified function within the specified time and under the given conditions. It not only directly reflects the quality of each component of the product, but also affects the quality of the entire product.
Reliability is divided into inherent reliability, service reliability and environmental adaptability. Reliability measures generally have three types: reliability, failure-free rate, and failure rate.
The study of reliability issues was developed during the Second World War to deal with the unreliability of electronic products. The research on reliability design used in machinery began in the 1960s and was first applied to military and aerospace industries, and then gradually expanded to civil industries.
For a complex product, in order to improve the performance of the overall system, it is achieved by improving the manufacturing accuracy of each component that constitutes the product; this makes the product expensive and sometimes difficult to achieve (for example, for tens of thousands of Even a very complex product composed of hundreds of thousands of parts).
In fact, the problem to be solved by reliability design is how to solve the reliability of the product from the design to improve the requirements for the reliability of each component (representing the probability of reliability). The allocation of reliability is the core of reliability design.
The distribution principles of reliability are as follows:
①Reliability is distributed according to importance.
②Reliability is allocated according to complexity.
③Reliability is allocated according to comprehensive indicators such as technical level and task conditions.
④The reliability is allocated according to the relative failure rate.
After each part has a definite reliability index, the design calculation of the parts is carried out according to different calculation criteria. The main calculation methods are: calculate reliability or required size according to the distribution of load and strength; calculate reliability or safe life according to the distribution of load and life; find the quantitative relationship between reliability and safety factor, and use the conventional design method to calculate The required size or the calculated safety factor. The data related to reliability design such as load, strength, size and life are all random variables and must be dealt with by probabilistic statistical methods.