Transient analysis of Long Piston With Cam using Ansys and studying effect of frictional coefficient on induced stress and strain
OBJECTIVE
To perform a transient analysis on a piston and cam mechanism model and run the analysis with Frictionless contact, Frictional with 0.1 and 0.2 as the frictional contact for a total of 3 cases.
Importing the CAD model
The CAD model is imported using spaceclaim and checked for any geometry errors.
Simulation setup
Material Assignment
All the parts are assigned with structural steel material. The barrel and barrel-cam are defined as Rigid structures, whereas the Cam follower is flexible in stiffness behavior.
Contact definition
Two contacts are defined in three different cases
Contact between Cam-follower to barrel
Contact between Cam-follower to barrel-cam
These two contacts are defined in three different cases
Case (1) - Frictionless contacts
Case (2) - Frictional contacts with friction coefficient of 0.1
Case (3) - Frictional contacts with friction coefficient of 0.2
Joint creation
Three joints are created to properly simulate the cam-piston motion.
A body-ground fixed joint is given to barrel cam.
A body-body translational joint is defined between barrel cam and cam follower, where cam follower is mobile body and barrel cam is reference body
To impart the motion, a revolute joint is assigned to the barrel such that it rotates around Z-axis
Mesh Generation
Face sizing of 3mm is given to cam follower head and barrel's contact surface with cam follower. Other parts are meshed with default settings
Analysis settings
The motion of the model is given in 9 steps with maximum time step value of 0.2
The energy dissipation ratio value is given as 0.1 with stabilizing force limit value as 0.2
The revolute joint of barrel is given a 270 degree rotation in 9 steps along z-axis. Thus the piston reciprocates in x-axis
Then the model is solved and following results are obtained
This result is for case (1) frictionless contacts
Results
Case (1) - Frictionless contacts
Directional deformation (x-axis)
Equivalent strain
Equivalent stress
Case (2) - Frictional contacts with friction coefficient of 0.1
Directional deformation (x-axis)
Equivalent strain
Equivalent stress
Case (3) - Frictional contacts with friction coefficient of 0.2
Directional deformation (x-axis)
Equivalent strain
Equivalent stress
Comparing three different cases
| Maximum Directional deformation (X-axis) | Maximum Equivalent Elastic Strain | Maximum Equivalent Elastic Stress | |
| Frictionless contact | 20.356 mm | 6.7487e-003 mm/mm | 1336.3 MPa |
| Frictional coefficient of 0.1 | 20.454 mm | 1.1059e-002 mm/mm | 2199.4 MPa |
| Frictional coefficient of 0.2 | 20.499 mm | 1.2039e-002 mm/mm | 2395.8 MPa |
It can be seen that as frictional coefficient increases it increases the frictional forces and thus the stress and strain increases.
Thus the case (3) with frictional coefficient of 0.2 has maximmum stress and strain.
Ansys file link
https://drive.google.com/file/d/1-sMQWJSX0kkkjtbT9AUlwoRaobKi1EgZ/view?usp=sharing