Fatigue analysis results interpretation

Pabllo Pires

Olá, sou de uma equipe de competição baja e estamos com algumas duvidas quanto à analise de fadiga do software HyperLife. Alguns pontos são:

- Como funciona a falha por fadiga analisada? O software interpreta a falha / tempo de vida / dano acumulado de cada um dos elementos, certo? 

- Segue um caso experimentado, onde simulamos uma manga de eixo do carro por meio de analise linear estatica com condições criticas de carregamento e, posteriormente, inserimos o .H2D no software HyperLife, configuramos a SN curve, mat, etc; e rodamos uma analise de fadiga, porém, sempre os gerados não condiz com a realidade, pois o componente falharia muito rapido. 

A seguir, tem-se algumas imagens do caso, e aceito qualquer sugestão sobre a tematica. 

ATT. 

 

Hello, I'm from a Baja competition team and we have some doubts regarding the fatigue analysis of the HyperLife software. Some points are:

- How does the analyzed fatigue failure work? The software interprets the failure/lifetime/accumulated damage of each of the elements, right?

- Below is an experienced case, where we simulated a car's steering knuckle through linear static analysis with critical loading conditions and, subsequently, inserted the .H2D into the HyperLife software, configured the SN curve, mat, etc.; and we ran a fatigue analysis, however, the results generated do not always match reality, as the component would fail very quickly.

Below are some images of the case, and I welcome any suggestions on the topic.

ATT.

Sravan Kumar Mothe

Hello, 

The software calculates fatigue life and damage on elements. I see you have solid elements, please create a skin on the surface and perform fatigue on skin elements. Generally cracks appear on the outer surface and propagate during the fatigue loading. From the images you shared I see life is less than one cycle  vs what are you seeing in reality(testing)? Here is the list of things you could do

1. First check the stresses or strains in the model Vs Strain Gauge data in testing. If they are completely off then we are not simulating the right load case. If the stress are similar then Hyperlife should predict the close results.

2. If the stress are close then check the stress level on SN curve and approximately estimate life. Hyperlife should give exact value. 

3. Checking the loading that you are simulating in real life and apply that load data in Hyperlife load map file. 

4. Use Multiaxial approach if you have non proportional loading.

5. Make sure you are using correct Materials. 

Please check and you could correct any of the above steps if you have missed anything.

Hope this information helps.

Thank you!

Sravan  Mothe