BMX Bike Demo Storyboard

1 © 2015 ANSYS, Inc. ANSYS Confidential

BMX Bike Demo Storyboard AIM 17.1


Introduction

• This demo illustrates fatigue life analysis in AIM, including interactive geometry parameterization and changes to study the effects of geometry dimensions on fatigue life.

• The design goal is to minimize the weight of a BMX bicycle frame while ensuring that its fatigue life is at least 100,000 cycles, per industry‐standard load tests and safety guidelines. This is done by adjusting the thickness of the frame tubes at discrete increments.

• For simplicity, the frame material is structural steel. Many performance bicycle frames are made of chromoly, an alloy of steel, chromium, molybdenum, and a few other things. One could define a custom material in AIM to simulate the behavior of chromoly for this model.

• All uses of this geometry model must include the statement, “Based on model courtesy of Guilherme Padilha”.


• Select ‘Structural’ template

• Enable ‘Allow model editing’

• Disable ‘Detect contact automatically’

• Enable ‘Compute fatigue results’

• ‘Create Simulation Process’

• Select ‘BMX Bike.scdoc’

Create Simulation Process


Edit Geometry

Based on model courtesy of Guilherme Padilha

Based on model courtesy of Guilherme Padilha


Suppress Unnecessary Parts

• Disable (hide) the following in the Structure tree – ‘Handlebars’ – ‘Seat’ (in ‘Seat and Post’ component) – ‘Front Wheel Assembly’ – ‘Rear Wheel Assembly’ – ‘Crankset and Pedals’ – ‘Midplane’


Create Tube Thickness Parameter (1/6)

• Select inner surfaces of tubes shown in red below – To select interior surfaces, hold Ctrl key, rotate mouse wheel, and click



• Invoke ‘Pull’ tool

• Click on Measure option



• Select both outer and inner surfaces of one tube – To select interior surface, hold Ctrl key, rotate mouse wheel, and click



• Select value for “Minimum distance between objects” in measurement table – Click on ‘2mm’ in right column, second row of table at bottom right



• Create parameter from driving dimension – Click on blue ‘[P]’ button at bottom right



• Rename parameter to “Tube Thickness” – Select ‘Groups’ tab below the structure tree – Right‐click on ‘Group1’ and choose ‘Rename’


Close Geometry Modeler


• Select ‘Mesh’ task

• Expand ‘Global Sizing’ group

• Change ‘Size function method’ to ‘Curvature’

• Generate mesh

Generate Mesh with Curvature Size Function


• Select ‘Physics’ task

• Select 4 orange faces at right – On rear of frame

• Add Support structural condition

Add Rear Support


• Select 2 orange faces at right – On front fork

• Add Support structural condition

Add Front Support


• Select orange face at right – Top of seat post

• Add Force structural condition – Directional components – Y = ‐1400 N

Add Seat Load


• Select ‘Physics’ task

• Add ‘Interface Generator’

• ‘Generate Interfaces’

Add Contact Interfaces


Confirm Contact Interfaces

• Select ‘Generated contacts (4)’ – Fork – Frame, Seat Post – Frame, Seat Post Pin – Frame (2)


Update Results


• Select ‘Equivalent Stress’

• Hide data panel (CDV) and Workflow

• Select ‘Displacement Magnitude’ – Animate

• Select ‘Fatigue Life’ – Zoom in to seat post area – Note that minimum value is much greater than minimum allowable of 100,000.

Review Results


Edit Geometry


Reduce Tube Thickness to 1 mm


Update Results


Review Fatigue Life Results


• Edit ‘Geometry’ task

• Change Tube Thickness to 1.5 mm

• Close geometry modeler

• Update ‘Results’ task

Increase Tube Thickness to 1.5 mm and Update Results


Review Fatigue Life Results


• Set the “Calculated minimum” as a parameter

• Click on the Design Point Dashboard icon

Alternative: Design Point Dashboard


Alternative: Design Point Dashboard

• Add the different tube thickness and select ‘Update All.’


Conclusion

BMX Bike Demo Storyboard

Documents

Transcript of BMX Bike Demo Storyboard