Mechanical reliability design can be divided into qualitative reliability design and quantitative reliability design. The so-called qualitative reliability design is in progress on the basis of the failure mode effects and criticality analysis, application design experience to achieve the purpose of reliable product design. The so-called quantitative reliability design is to fully grasp the intensity distribution of the designed parts, and stress distribution as well as various design parameters randomness basis through the establishment of the relationship between implicit limit state function or an explicit limit state function designed to meet the specified reliability requirements products.
Mechanical reliability design method is a commonly used method is to carry out the design of the mechanical reliability of one of the most direct and effective way, regardless of structural reliability design or institutional reliability design a large number of commonly used methods. Reliability of quantitative design in accordance with the reliability index design to meet the requirements of the appropriate parts, but is still a lack of specific data because of the intensity distribution of the material and load distribution, coupled with which to consider many factors, thus paste filling machine its marketing application. generally adopted in the critical or important parts of the design.
Mechanical reliability design can be used due to the differences of the different products and composition of the reliability design method:
(1) prevention of fail-safe design
Mechanical products in general belong to the series system to improve the reliability, should first of all parts of the strict selection and control to start. For example, the preferred standard parts and common parts; selected after analysis to verify the reliable components; in strict accordance with the standard choice and control of purchased parts; make full use of the results of failure analysis, the use of mature experience or experimental verification solution.
(2) simplify the design
Meet the intended function, the mechanical design should be simple, the number of parts should be minimized, the more simple the more reliable is a basic principle of reliability design, the most effective way to improve reliability is to reduce the failure. But not by reducing the parts leaving the other parts to perform extraordinary functions or work in high-stress conditions. Otherwise, to simplify the design to reach less than the purpose of improving reliability.
3 derating design and margin of safety design
Derating design is the use of parts of the stress less than its integrated oil press stress of a design method. Derating design can be achieved by reducing the parts to withstand the stress or the way to improve the strength of parts. Engineering experience has shown that most of the mechanical parts in less than the rated carrying stress conditions, the low failure rate, high reliability. In order to find the optimal derating values, you need to do a lot of trial studies. When the load stress and the strength to withstand the stress of the specific components of the mechanical parts was uncertain distribution within a certain range, you can increase the average intensity (such as a large increase in safety factor) to reduce the average stress, reduce stress (eg, through restrictions on the conditions of use) and reduce the intensity of change (such as a reasonable choice of technology, strict control over the entire process, or removed by inspection or testing failed parts) method to improve reliability. Important for safety-related components, but also can be used to limit design method to ensure that the worst of the limit state will not malfunction.