Summary

Today the calculation and proof of strength, endurance limit and fatigue limit is an important part of the development process of technical components. In many cases it leads to a more intelligent use of the material and a reduced weight. These improvements are also very important in view of legal aspects, in particular product liability.

The development process has the following phases:

The first is to prove the strength of the component under maximum but seldom acting loadings, including a suitable safety. This proof is the prerequisite for all following steps in the development process.

If the component is loaded dynamically, you also have to prove the reliability. If the acting stresses resulting from the loading are considerably lower than the endurance limit, then it is relatively simple to prove the endurance limit assuming a worst case scenario. If the distance to the endurance limit is sufficient, then further investigations may not be necessary (depending on the safety relevance of the component).

At a later development stage - when the goal is an optimization of the structure and when more details of the construction are available - a fatigue analysis may be necessary.

Furthermore, a crack growth analysis may be helpful if inspection intervals have to be defined.

winLIFE supports all the named steps from preparing a load spectrum through to printing a report. The winLIFE development team also offers fatigue analyses in close collaboration with the customer.

The winLIFE Program (Fatigue Life Information using Finite Elements) enables the user to calculate all processes starting with the static proof through to the calculation of fatigue life under dynamic loading. The calculation can be done in the classic way (without FEA) based on nominal stresses or by way of local strain approach using notch factors in the usual manner to describe the local effects in the notch.

If you use winLIFE with Finite Elements Analysis (FEA), the stress of each node can be imported into winLIFE as a base for a fatigue calculation.

Fatigue calculation can only deal with a trend prediction. Safety relevant components must be tested additionally by experiments and rig tests. The statistical phenomena of fatigue makes testing very expensive because of the large number of tests required. The fatigue life calculation helps to identify the important parameters and assists you to reduce the necessary number of tests.

Fatigue life calculation enables relative fatigue life prediction and it is possible to estimate the fatigue life at an early stage of the development process. The development process of dynamic loaded components can be shortened considerably.

If, in addition to the calculation, component tests and damage analysis of customers’ components are carried out, considerable long-term benefits can be achieved.  This is the only way to achieve a sound basis for reliable and numerical fatigue life predictions.

Despite the easy use of winLIFE you need a good knowledge in fatigue, because there are many parameters to be set and only a correct understanding will lead to correct results.

We offer training seminars 3 times a year to introduce winLIFE to the user. We can also carry out the fatigue calculation for you to your own requirements.