ABSTRACT
This procedure can be applied to another stress levels, Si, and the fraction of the fatigue life used is Ni/Nfi. The Palmgren-Miner rule, which is widely used in civil engineering, simply states that failure is expected when such fatigue life fractions sum to unity or whenever all of the fatigue life is exhausted. This rule was developed based on the work done by A. Palmgren in 1924 and later modified by M.A. Miner (1945). The rule is based on the assumption that the fatigue damage at a given stress level can be accumulated linearly with the number of stress cycles. For example, for a general multi-level loading, the Palmgren-Miner rule can be presented by the following equation:
N N
N N
N Nf f
2 1+ + == ∑ (1)
To use the Palmgen-Miner rule it is necessary to have the S-N (the stress level versus the number of cycles to failure) curve for the element or component to analyze. In this study, the S-N curve for the RBS connections is developed.
