What really counts in judging component failure.( Max. Prince. Stress, von mieses.)
What really counts in judging component failure.( Max. Prince. Stress, von mieses.)
(OP)
Hallo dear Friends,
I have a FEM model which should fullfil the technical Standard sent from OEMs.
. Component stifness should be Not less than 200 N/mm under static loading.
The question as Follow:
1. Who can explain me which type of Stress Evaluation really counts. And what is the idea behind Max.princible stress (i am Not Looking for book definition).
2. How to find the stifness k=F/d Analytically for Component having complex Geometry?
I dont want to be a guys Who just bild a FE-models without having a check B .(analytical approach).
I will be thankfull for Any help.
I have a FEM model which should fullfil the technical Standard sent from OEMs.
. Component stifness should be Not less than 200 N/mm under static loading.
The question as Follow:
1. Who can explain me which type of Stress Evaluation really counts. And what is the idea behind Max.princible stress (i am Not Looking for book definition).
2. How to find the stifness k=F/d Analytically for Component having complex Geometry?
I dont want to be a guys Who just bild a FE-models without having a check B .(analytical approach).
I will be thankfull for Any help.





RE: What really counts in judging component failure.( Max. Prince. Stress, von mieses.)
To find the stiffness of something you apply a force and calculate the displacement and divide the two.
RE: What really counts in judging component failure.( Max. Prince. Stress, von mieses.)
Regarding to my little experince, static loading is very deterministic. If part fail at ex. 10 MPa under static loading. I guess failure Progression ocours earlier in dynamic loading. The idea is to Start with static stifness and i would like to know if Anyone knows a method where geometrically complex parts can be idealized and an approximate analytical solution is Found.the idea is a Bit far from simple be am under converting load. Summing up, Which stress creteria is important under static loading and what to Check for?
RE: What really counts in judging component failure.( Max. Prince. Stress, von mieses.)
another day in paradise, or is paradise one day closer ?
RE: What really counts in judging component failure.( Max. Prince. Stress, von mieses.)
as for how to do analytical hand calc for deflection and hence stiffness of complex part. you need an approximation for the geometry and then dig out a handbook with a similar case
RE: What really counts in judging component failure.( Max. Prince. Stress, von mieses.)
k=F/x
Where:
F: Force applied
x: displacement
k: stiffness
Tips:
- If it's a non-linear results desconsider all I said
- The displacement should be along to your model and not resultant component
- The final results will be the stifness
As far as I'm aware von mises is used to ductile material and maximum principal for fragile material and fatigue calculation.
Maximum Principal > traction
Minimum Principal > compression
RE: What really counts in judging component failure.( Max. Prince. Stress, von mieses.)
But it is only suitable as the critical failure stress indicator for brittle materials such as cast iron, concrete etc.
In general, Von Mises is used for ductile yield failure prediction. About complex geometry stiffness calculations the boys have spoken already above.
In aerospace, its more of a combined stress interaction equation.
There are many good videos on failure criteria on youtube, you should check those out. They go into high detail on different failure theories.
www.stressebook.com
Stressing Stresslessly!
RE: What really counts in judging component failure.( Max. Prince. Stress, von mieses.)