Non-Linear/Dynamic Analysis of Ball And Socket

Joint

By: Sumit Bhattacharya 710 Abhishek Bhoite 711 Sharvil Dalvi 713

Department Of Mechanical Engineering

Dynamic Analysis:

Linear static analysis can be performed if:• Material is linear elastic• Deformations are small• Load and restraints are constantly appliedA linear static solution is not valid if above points are violated

The relationship in such cases, between the loads and response become non-linear and thus Dynamic Analysis must be performed to get accurate results.

Types Of Non-Linear Analysis:

• Material Non-linearity (plasticity, Creep, Viscoelastic)

• Geometric Non-linearity (Large deformations, strains)

• Contact Non-Linearity

There can be combination of both as well

Characteristics and General Recommendation:• The analyst should have insight into behavior of structure• Sub-structuring should be considered• The size should be determined based on purpose of analysis• Prior contemplation of geometric modelling will increase efficiency• Discretization should be based on stress gradient• Element types and mesh size should be carefully chosen

• Material Non-Linearity: Characterized by material properties, although the effects may or may not be significant. The anticipated stress level would be a key to this issue.

• Geometric Non-Linearity: Characterized by large rotations which cause large displacements. The geometric non-linear effects are related to the dimensions of structure and boundary conditions. The key is to know where loading point in the load-deflection curve of critical area is.

• Contact Non-Linearity:  Contact can also be classified as a geometric nonlinearity because the area of contact is a function of the deformation (some authors puts contact in another class called nonlinear boundary conditions).

Benefits of Non-Linear Analysis:• Reduce design risk by using simulation to save time and cost

• Accelerate innovation

• Improve reliability of final design

• Obtain more accurate solution

Ball and socket joint

• The mechanical joint allows some relative angular motion between parts in nearly all directions.• The joint consists essentially of a spherical knob at the end of a shaft,

with the knob fitting securely into a mating socket.• Applications-1. Suspension and steering mechanisms2. Mechanical wipers

Ball And Socket Joint

Mass Property Calculation:

Contact Non-Linear Analysis of a socket made of Nylon

The ball and socket joint similar to those used in windshield wiping system is analyzed using NX-NASTRAN. The joint consists of a steel ball pressed into nylon socket that has been insert-molded onto a steel connecting rod.

Problem Definition: To check the axial force required to pull the ball out of socket against axial displacement

Procedure• Three D Model• Idealization of the body• Perform 2D meshing• Apply contact and boundary conditions• Solve using Advanced Nonlinear solution sequence• Interpret post processing process• Plot graph

Three Dimension Model:This is a three Dimensional modelOf Ball and socket Jointmade in any CAD software andThe model is idealized.For proper analysis is spilt the body.

Meshing• Element: 2D• Collector type: Solid Axisymmetric• Solid Props: Nylon for socket and steel for ball• Mesh type: 2D• Mesh Element : CQUADX 8• Meshing method: paver• Element Size: 0.5mm

Boundary Conditions• Fixed Constraint• User Defined Constraint• Enforced Displacement constraint: Where we specify the values of time and length and specify the node where it is subjected.• Axisymmetric Non-Linear Contact

Post Processing

The Nodal Displacement is shown in the Z Direction.

• The Maximum Value is 0.023mm

• The Minimum Value is -2 mm

Axial Force VS Axial displacement

Conclusions:

Analyzed the socket made of nylon subjected to pressure on its body. We see the concept of time defining the increase of displacement during analysis.Some observations:• Data of iteration 1 is at right end of curve and iteration 30 is at left end

of curve• The ball separates from the socket between 0mm and about -2.00mm.• From -2.00mm to -4.00mm, the reaction force balances the spring

back force produced by socket.