Domainpower
Mechanical
- Sep 13, 2012
- 20
Problem description:
I have a test model which has a radial clearance (initial gap)of 0.005 mm around two pins which are holding a mass rotating at some angular velocity(Centrifugal force).The model is created taking advantage of cyclic symmetry and symmetry plane.
I used Ansys workbench 13.0 for my Fea model.The two pins do not have any constraints and are held only by contact ( z direction constraint on the pin is due to symmetry plane)
I started contact pair with : augumented lagrange + Asymmetric behaviour+ Pin surface as contact surface + update stiffness each iteration aggressively + friction coeefecient 0.2
To get the exact gap modeled in FEA i used Interface treatment setting of Add offset , ramped effects with some add offset value.
also used pinball radius of 3 mm.
Dimensions of the pins are 10 mm and 8 mm
Elements used are Solid187.SOLID187 element is a higher order 3-D, 10-node element.Also i read in some threads higher order is not suited for contact analysis , but i think in some threads they mention for ansys it is ok.
No other constraint is applied to the model , as the model is cyclic symmetric , the centrifugal force gets balanced.
I have attached the picture for better understanding.
But when i solve i get huge displacement.The contact doesn't seem to be active.
My first question:
why after my first run i got huge displacement as if the contact is not working even though i kept my pin ball radius 3 mm larger than my initial gap of 0.005mm.Can somebody summarize the influence of the Pin ball radius with initial penetration/ initial gap.
My second question :
I read through some of the threads and found a way which suggests to preload the contact pair by imposing a displacement in the first load step and then ramping the load up in the second load step along with removing the imposed displacement which will redistribute the load at the contact pair as per the applied loading.So i will imposed the displacements in the pin in the direction of the applied load and then in the second load step apply the angular velocity and removed the imposed displacement. Is it okay.
Rajesh
Alstom Power
I have a test model which has a radial clearance (initial gap)of 0.005 mm around two pins which are holding a mass rotating at some angular velocity(Centrifugal force).The model is created taking advantage of cyclic symmetry and symmetry plane.
I used Ansys workbench 13.0 for my Fea model.The two pins do not have any constraints and are held only by contact ( z direction constraint on the pin is due to symmetry plane)
I started contact pair with : augumented lagrange + Asymmetric behaviour+ Pin surface as contact surface + update stiffness each iteration aggressively + friction coeefecient 0.2
To get the exact gap modeled in FEA i used Interface treatment setting of Add offset , ramped effects with some add offset value.
also used pinball radius of 3 mm.
Dimensions of the pins are 10 mm and 8 mm
Elements used are Solid187.SOLID187 element is a higher order 3-D, 10-node element.Also i read in some threads higher order is not suited for contact analysis , but i think in some threads they mention for ansys it is ok.
No other constraint is applied to the model , as the model is cyclic symmetric , the centrifugal force gets balanced.
I have attached the picture for better understanding.
But when i solve i get huge displacement.The contact doesn't seem to be active.
My first question:
why after my first run i got huge displacement as if the contact is not working even though i kept my pin ball radius 3 mm larger than my initial gap of 0.005mm.Can somebody summarize the influence of the Pin ball radius with initial penetration/ initial gap.
My second question :
I read through some of the threads and found a way which suggests to preload the contact pair by imposing a displacement in the first load step and then ramping the load up in the second load step along with removing the imposed displacement which will redistribute the load at the contact pair as per the applied loading.So i will imposed the displacements in the pin in the direction of the applied load and then in the second load step apply the angular velocity and removed the imposed displacement. Is it okay.
Rajesh
Alstom Power
