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C H A P T E R 4
Reliability of a Component
under Static Load
4.1 INTRODUCTION
According to the applied loading on a component, component design typically can be grouped
into component design under static loading and component design under cyclic loading. is
chapter will discuss component design under static loading. e component design under cyclic
loading will be discussed in the book of Reliability-Based Mechanical Design, Volume 2: Component
under Cyclic Load and Dimension Design with Required Reliability.
According to the task of component design, component design can be grouped into com-
ponent design check and component dimension design. Component design check means that
we check the actual reliability of a component when loading, geometric dimensions, and material
properties are all specified. If the actual reliability of the component is larger than the specified
reliability, the component is classified as a qualified design. Otherwise, the component needs to
be redesigned. Component dimension design refers that we design component dimensions with
the required reliability under the specified loading and material. is chapter will discuss com-
ponent design check for a component under static loading. e component dimension design
will be discussed in the book of Reliability-based Mechanical Design, Volume 2: Component under
Cyclic Load and Dimension Design with Required Reliability.
In this chapter, first, we will discuss how to describe all design parameters: dimension,
loading, and material properties as random variables. en we will discuss the reliability of
component under some typical static loadings such as rod under axial loading, pin under direct
shearing, shaft under torsion, beam under bending. Finally, we will discuss component under
combined loadings.
4.2 GEOMETRIC DIMENSION AS A RANDOM VARIABLE
Any geometric dimension is always associated with a corresponding dimension tolerance, which
is controlled by a manufacturing process. For example, the possible dimension tolerance of a
component dimension between 0.4
00
–1.97
00
vs. its different manufacturing processes [1] are listed
in Table 4.1.
e geometric dimensions of a component can be classified as a free dimension and a
mating dimension. A free dimension refers that the variation of the dimension will not affect