Overiew

This page explores the parameters defining the nature and behavior of collision objects in our impact analysis. The goals of this investigation are listed below.

• Gain a better understanding of the real life representation of the collision objects in order to accurately model their behavior in collision scenarios

• Verify the size, geometry and material of collision objects and ensure they meet ASC regulations

• Re-evaluate contact types and fixed supports used in the current simulation setup

• Propose new simulation setups that can model the behaviour of the chassis and collision objects more realistically

• Ensure models are sufficiently constrained and can be solved by running test cases in Ansys

Left To Do:

• double check the automatic contacts in the current model

• finish defining set up cases

• run in ansys

• compare to existing results (stresses, model behavior)

  • ideal result = lower stresses but still realistically modelled

1.0 ASC Regulations Regarding Collision Objects

Relevant regulations and figures are listed below.

1.1 Collision Object Specifications Based on ASC Regulations

Specifications for collision objects based on regulation are summarized in the table below.

1.2 Current Collision Objects Setup:

This page summarizes all collision scenario cases: MS14 Simulations Overview

Information on our current collision objects setup is summarized in the table below.

• We should consider adding and running simulations involving the following objects/scenarios:
  1) Front and side 100 mm x 600 mm objects *
  2) Top “puck” objects.
  
  Note: there is a separate file (named “extra sims”?) that already includes these objects, but the simulation file has been corrupted.
  * location of this shorter bar is important (centered? offset?)
• We should also investigate material selection for the collision object to more accurately model the behaviour of the real objects they represent.
  
  For example, the bars representing bumpers can be either steel or alumnum.

2.0 Ansys Contact Types and Behaviours

https://www.mechead.com/contact-types-and-behaviours-in-ansys/

The current model set up uses the Bonded contact type between collision objects and the chassis tubes.

A table summarizing contact types in ansys is shown. More details on the options are summarized in the drop down below.

 Contact Types and Behavior

2.1 Bonded

• default configuration and applies to all contact regions (surfaces, solids, lines, faces, edges)

• no sliding or separation between faces and edges (think glued)

• contact area doesn’t change with loading

• linear solution

2.2 No Separation

• cannot separate objects, but can slide

• nodes in contact are bonded to the target surface

2.3 Frictionless

• can separate and slide

• standard unilateral contact - gaps can form between the bodies depending on loading

• non-linear solutions - area of contact changes with loading

• model should be well constrained

2.4 Frictional

• can separate and slide with resistance ( modelled with shear stresses)

2.5 Rough

• can separate, no sliding

• does not close any gaps

• We should use the Frictionless contact type between the collision objects (bars, pucks, walls) and chassis.
  
  This constraint models basic unilateral contact and will allow for deformation of both bodies and gaps to form between them. However, we should be careful with sliding. Additional constraints are required to fully contain the movement of the chassis and ensure the simulation can be solved.

3.0 Model Setup

3.1 Existing Set-up

• See this page for details on the current Ansys Workbench Setup: MS14 Workbench Setup

  • “11. Add a fixed support to the back face of your impact object”

  • “12. Add acceleration to your model, in the direction away from the impact object. For every G of force you want to simulate, add 9.8m/s^2 to acceleration (i.e. for 5Gs, acceleration should be 49m/s^2).”

3.2 Front/ Side Bar Collisions Setup

3.3 Rollover (Wall) Collisions Setup

3.3 Top (Pucks) Collision Setup

4.0 Simulation Results

• Show results based on setups defined in 3.0

• take note of any modifications / iterations required

4.1 Case 1 Results

4.2 Case 2 Results

4.3 Case 3 Results

5.0 Other Resources:

• Ansys static structural: ANSYS - Static Structural Analysis

  • analysis settings

  • types of loads

  • types of supports

  • types of results