Transient Structural Analysis of Slider Crank Mechanism using Ansys Workbench

Objective: Perform Transient Structural Analysis on Slider Crank Mechanism and write a detailed report explaining the results obtained for the question.

Question:

For this challenge, Simulate the slider crank mechanism for the cases given below.

Case 1: Run the simulation as mentioned in the video

Case 2: Create contacts between the various slider crank components and assign material properties to the geometry with frictional coefficient as per given below,

Geometry	Materials	Coefficient of friction
Crank to Handle 1	Structural steel - Low Carbon Steel	0.3
Handle 1 to Handle 2	Low Carbon Steel - Grey Cast iron	0.23
Handle 2 to Fixture	Gray cast iron - Grey cast iron	0.15

Results and Deliverables

• Obtain total deformation, equivalent stress and total velocity generated by crank.
• Also find the frictional stress generated due to friction for the various contacts in the model.

Case Setup and Execution:

Model:

Boundary Conditions:

Joints: Joints has been applied as shown below.

Analysis Settings: From Time step 2 to 4, carry over time step is switched on.

Joint Loads: Joint Loads has been applied as shown below.

Case-1:

Boundary Conditions:

Material: STRUCTURAL STEEL for all parts.

Mesh: Size of element - 10mm.

Results:

Equivalent Stress:

Equivalent Stress for Crank:

Total Deformation:

Total Deformation for Crank:

Total Velocity for Crank:

Case-2:

Boundary Conditions:

Material:

STRUCTURAL STEEL for Crank.

LOW CARBON STEEL for Handle 1.

GRAY CAST IRON for Handle 2 & Fixture.

Contacts: Frictional Contact has been applied between Crank and Handle 1 with 0.3 as coefficient of friction.

Frictional Contact has been applied between Handle 1 and Handle 2 with 0.23 as coefficient of friction.

Frictional Contact has been applied between Handle 2 and Fixture with 0.15 as coefficient of friction.

Mesh: Size of element- 15mm.

Face Sizing: Face Sizing with element size of 5mm has been applied on the faces which come into contact.

Results:

Equivalent Stress:

Equivalent Stress for Crank:

Total Deformation:

Total Deformation for Crank:

Total Velocity for Crank:

Frictional Stress: Crank to Handle 1

Frictional Stress: Handle 1 to Handle 2

Frictional Stress: Handle 2 to Fixture

Results Comparison & Conclusion:

Results Comparison:

For CRANK	Total Deformation		Total Velocity		Equivalent Stress
	mm		mm/s		Mpa
	Min.	Max.	Min.	Max.	Min.	Max.
Case-1	0.53152	179.97	7.0891	270.63	1.53E-10	0.54909
Case-2	0.53152	179.97	15.646	141.08	1.87E-03	137.75

• Total deformation is same for all cases, as the direction & path of movement is same for both the cases.
• Total Velocity is higher in case-1 as there is no friction acting on the contacts and the velocity is reduced to overcome the friction in Case-2.
• Equivalent Stress is lower in Case-1 as there is no friction acting on the contacts and the stress is increased to overcome the friction in Case-2.
• Max. frictional stress is experienced by the rotational joint between crank and handle 1. There are two reasons for the same i. Due to high frictional coefficent than the rest 2 contacts. ii. As the joint load is on the crank, the stress or velocity generated at the crank is usually high which in turn increases friction between the contacts and as the motion is transmitted to the last contact, there is a substantial reduction in velocity due to losses which in turn reduces stress and friction between contact Handle 2 and Fixture.
• So coefficient of friction, path of movement and frictional stress follows the path Crank to Handle 1>Handle 1 to Handle 2>Handle 2 and Fixture.