Project 2

Objective: To mesh and deploy connections for the given automobile rear wheels suspension assembly using ANSA

Quality criteria followed:

Quality Criteria for Tria Elements (Tyre and Rim):

S.No	Quality Criteria	Value
1	Target/Average length	6.5
2	Minimum Length	5
3	Maximum Length	10
4	Skewness	45

Quality criteria for Mixed elements (For Midsurface only):

S.No	Quality Criteria	Value
1	Target/Average length	4
2	Minimum Length	2
3	Maximum Length	6
4	Aspect	3
5	Warpage	15
6	Skewness	45
7	Jacobian	0.7
8	Minimum Quad Angle	45
9	Maximum Quad Angle	135
10	Minimum Tria Angle	30
11	Maximum Tria Angle	120

Quality criteria for Tria (For other components):

S.No	Quality Criteria	Value
1	Target/Average length	4
2	Minimum Length	2
3	Maximum Length	6
4	Skewness	45

Common Quality Criteria for Tetra elements are:

S.No	Quality Criteria	Value
1	Tet-collapse	0.2

About the Rear wheels suspension assembly:

The suspension system of a vehicle refers to the group of mechanical components that connect the wheels to the frame or body. A great deal of engineering effort has gone into the design of suspension systems because of an unending effort to improve vehicle ride and handling along with passenger safety and comfort. In the horse and buggy days, the suspension system consisted merely of a beam (axle) that extended across the width of the vehicle. In the front, the wheels were mounted to the axle ends and the axle was rotated at the center to provide steering. The early automobiles used the one‐piece axle design but instead of being rotated at the center, it was fix‐mounted to the vehicle through springs to provide the cushioning of shock loads from road inaccuracies. The wheels were rotationally‐mounted at the axle ends to provide steering. The first springs consisted of thin layers of narrow pieces of strip steel stacked together in an elliptical shape and were called leaf springs. In later installations, leaf springs were replaced by coil springs. In front‐engine rear‐drive vehicles, the front beam axle was replaced by independently mounted steerable wheels. The wheels were supported by short upper and lower hinged arms holding them perpendicular to the road as did the previous axle beam designs. A coil spring was used to support either the upper or the lower arm to provide dampening. Shock absorbers began to be used to dampen shock loads and also to provide resistance to spring oscillations. Later it was learned by shortening the upper arm; wheel tilt (camber) could be controlled to prevent edge loading tires while cornering. The power transmitting drive axle in the rear served as the beam‐type suspension with dampening provided by either leaf or coil springs as well as shock absorbers. When front‐engine front‐drive passenger cars were introduced, the upper arm was rotated up and replaced by a member called a “strut” which contained the concentrically mounted spring and shock. This arrangement provided additional space for transverse mounted engine/transmission modules and the front drive shaft. This same type of suspension was also used in the rear of many cars. Trucks continue to be front‐engine, rear‐drive vehicles many of which are using beam‐ type axle suspension systems in both the front and rear.

Procedure:

• Import the cad model onto ANSA workspace and perform a topology
• Check for geometrical errors and fix them manually or using auto fix option
• Identify the parts which needs to be 1D meshed, Shell meshed and Solid meshed
• Select the parts which are to be shell meshed and extract mid surface of all of them
• Set separate PID’s and assign thickness values to them
• Apply the mesh parameters and quality parameters values and mesh the midplanes accordingly
• Using hidden mode find the off elements and rectify them
• Now select the parts for solid meshing and start meshing on their surfaces
• OrthoTria mesh is used on curved surfaces and tria mesh is used on planar surfaces
• For volume mesh , either TetraRapid or TetraFEM algorithm is followed
• Collapsed elements are visible in hidden mode and needs to be rectified
• For coil spring, 1D meshing is done, and for this a center curved line along the axis of rod is taken. C-Bar connection is done for this.
• By choosing proper element value, 1D meshing is done
• The type of connections followed here are bolt connections and weld connections
• When bolt data is not available, a RBE2 cluster (RBE2 Single cluster/RBE2 spider) is made, which is either a 2 node RBE2 or many node RBE2 connection.
• Seam weld connections are done using connections manager with FE Rep Type of overlap shell

Images for reference:

Link:https://drive.google.com/file/d/1dMmiChG1KpCDpFWuaMpHkSbHXPzsOp2T/view?usp=sharing

Conclusion:Meshing with connections for rear suspension is done using ANSA