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Variable Side Load

sudhishjoseph

New member
2004-12-12_092050_bottom_housing.prt.zip


Hello,


The model made in Wf2(educational version) is a housing. It has a constant vertical load of 5.6 tonne(uniform) acting downwards.There is a variable load on the side surface(acting on the cylindrical surface). I want to find out when it will fail due to the side load,especially at the filleted area on the lower side. The bottom side of the housing is fixed.


I made a quarter portion of the model and fixed Z (translation)in the XZ Plane and the X(translational constraint) in the YZ Plane. I also fixed the Y& Z (translation)at the bottom surface.I applied a vertical load of (5.6*9.8*1000)/4 (model is in N-mm-s)towards bottom & a side load of (9.8*3*1000) (assuming side load of 3tonne).Is this the correct way?The material is Forged Steel(Young's modulus of 2.1* e+011 Pa,Poisson's ration 0.28).


Could any one guide me.


Thank you,


Sudhish
 

puppet

Moderator
hey israr :) any chance u know of some good tutorials for that kinda of analysis:)



or even point me in the right direction ?
 

Luis Aguirre

New member
Sudhish,



It seems that Israr is helping you already but here is the way I will
approach this problem. Do to the fact that most FEA codes
use a linear solution to approach stress you can super impose different
loads to see what is their individual contribution to the total stress.
In mechanica you must assign a load set to each of the loads you will
apply. For example you may call the first load set
"vertical_load" and the second load set "cylinder_load". Since I
don't have a picture of your model I will assume you setup the model
symmetical constrains propertly. Once the model is setup create an
analysis window. In the analysis window you will see both of the load
sets you created make sure both of them are higlighted so mechanica can
give you indipendent resulst for each load. Run the anlysis and create
a results window. In the results window you will have the option
look at each load stress contribution individually or combined. You can
also assign a load factor ( Increase the load you initially assign by a
multiplier). To find out when the part will yield,
look at the maximum von mises stress for the "vertical load" and
write it down. Look for the von mises stress for the
"cylindrical_load" by it self and write down. Now created
another window to look at the combine stress of both loads and
see if your maximum von mises stress changed when you compare it
to the cylindrical load. If did not change by much then the
"cylindrical load is the biggest contributor for the stress in your
model. TO find out whan cylindrical load will yield the material
the use the following formula:





Yielding stress of material= ( Von mises due to vertical load)+( Von mises due to cylindircal load )* Factor





TO find out what "factor" you must multiply your original force to
yield the material solve for the variable "factor" in the above
equation.





Factor= ((Yielding stress of material)-(Von mises due to vertical load))


---------------------------------------------- ------------------------

&nbs p;&nbs p;&nbs p;
( Von mises due to cylindircal load )







Now that you calculated the factor that you must multiply the
cylindrical load create a new results window and combine both loads.
Leave the multiplier factor equal to 1 for the vertical load but change
the number you calculated in the above equation for the multiplier of
the cylindrical load. Look at the results for the combine load
von mises stress and the maximum value should be very close to the
yield stress of the material.





Again I am assuming you setup your constraints properly for this to work.





Luis

&nbs p;&nbs p;
 

sudhishjoseph

New member
Hello


Luis I have uploaded 2 image files of the assembly & of constrained 1/4 part. Pls see if it is ok. I tried your guidance but the values of deformation on combined load is absurd like 1metre when the whole assy. is only 143mm ht.


Also can u tell me how to use the Failure Index.


Hope u can help. Thanks in advance. 2004-12-17_100311_new1.zipAlso zipped the images.


Israr sending you the files in ur mail. Thank you.


Sudhish
 

Luis Aguirre

New member
Sudhish,


Usually large displacement is due to an error in entering the material properties. Make sure you change the material units to IPS in ProE before you go into MECHANICA. Then assign the material properties in MECHANICA DON'T use the ones transfer from ProE default.








Luis
Edited by: Luis Aguirre
 

sudhishjoseph

New member
Hello Luis,

How should I convert the units meaning should I convert only the matrerial property in IPS or the whole model into IPS.

Please guide.

Thank you,

Sudhish
 

Luis Aguirre

New member
Convert the whole model to IPS then assign the material properties in MECHANICA and make sure you review the loads already assign to the model. Most likely the load magnitude will change once you covert your model to IPS





Luis
Edited by: Luis Aguirre
 

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