Presented by: Sergio G. Arias, Ph. D. Simulia Community Conference 2012, Providence, RI Date: May 16, 2012

Transcription

1 Presented by: Sergio G. Arias, Ph. D. Location: Simulia Community Conference 2012, Providence, RI Date:, Camoplast Solideal Inc. All rights reserved.

2 Presentation Outline - Company background information - Project Description, Objectives - Experimental Test and Results - Modeling of experiment in FEA - Validation of computer model - Discussion and Conclusion - Questions 1

3 Camoplast Solideal, Inc. Founded in 1982, Camoplast Solideal is the world leading specialist in the design, manufacturing, and distribution of rubber tracks, off-road tires, wheels, undercarriage systems, automotive plastic components and assemblies, molded skis and engine covers. We offer our experience, engineering expertise, innovation skills, support and best-in-class manufacturing capabilities to deliver high performance products. Construction tires and wheels and tracks Agriculture tracks and systems ATV/UTV track and systems Snowmobile tracks and skis Polymer Solutions Group For more information, you can visit our website: 2

4 Camoplast Solideal, Inc. A global team of more than 8000 dedicated employees, we have manufacturing facilities in USA, Canada, Asia and Europe. The Camoplast Technology Center (CTC) is in Magog, Québec. 3

5 Presentation Outline - Project Description and Objectives - Experimental Test and Results 4

6 Project Description Case Study: Abnormal wear development found in the rubber tracks of caterpillar-type vehicles, such as agriculture tractors. Problem Description: Field observations of a particular rubber track have shown uneven wear in the contact patch of the treads. This irregular wear may affect to some degree the performance of traction, maneuvering, vibration and track life. The reason of this wear behavior is not very clear, therefore Camoplast Solideal decided to conduct intensive experimental and simulation analysis to understand better this wear phenomena. 5

7 Project Objectives Goal: The purpose of this project is to have an understanding of the wear development on the treads of these rubber tracks, so we can correct this issue and, improve their overall performance. The project was divided into two main stages: Field/Experimental Testing: A field test to replicate the wear phenomena, and verify its failure. A laboratory test was performed to study closely the tread behavior. A microscopic analysis to the tread surface to determine wear mechanism. Computer Simulation: FEA codes were used to simulate the mechanism of stresses generated at the treads. Validation of the computer model was based on pressure scanned recordings from TEKSCAN. Once validated, consequent analysis can be conducted to reduce the abnormal wear development and improve tread wear performance. 6

8 Experimental Setup Laboratory Setup: a special rig was constructed to visualize the tread movement as the track rolled over a glassy surface, in which a camera was placed underneath. Tread setup: A certain number of treads were specially marked to record in better detail the movement of the treads when they contact the surface. 7

9 Laboratory Test Microscopic Analysis: two treads were extracted from a worn-out track, and taken under a microscope. The purpose for this visualization was to observe the roughness, and striation structure of the two, clearly defined contact areas of the tread Rough Area: angled, large-size striations. (Schallamach waves) Rough Area Smooth Area fingerprint-like surface 8

10 Laboratory Test Smooth Area: Low-angled, very smooth, large striations (not visible to the eye). 9

11 Experimental Results From the experimental setup: Two areas of contact can be seen from the experiment with distinct surface tread movements. From the microscopic analysis: The wear rate in the smooth area is much larger than in the rough area. The two areas have well defined and different striation structure and orientation: clearly the wear mechanism is different between the two areas. The difference in tread movement and wear pattern suggests that abnormal wear is correlated with a difference in contact pressure and surface tread movement between the two areas. 10

12 Presentation Outline - Modeling of experiment in FEA - Validation of computer model 11

13 Simulation of Project in FEA Goal: to replicate the experimental test conducted earlier, and obtain a correlation of the abnormal wear development with the variances in pressures and motions at the surface contact of the treads. Setup, Simplifications & Assumptions: The components affecting the abnormal wear were the Midrollers. Effects of idlers were not considered. The modeling of the surface would be that of a concrete floor (rigid surface). A friction coefficient of 0.1 was used. Bias cabling (reinforcement) was left out in the simulation. 12

14 Modeling and Pre-processing Assembly Components: 1. Carcass 2. Drive Lugs 3. Treads 4. Reinforcement l 0-degree 5. Midrollers 6. Undercarriage 7. Ground Rubber modeling: All rubber materials were pre-strained and characterized for tension, planar and equibiaxial conditions. Reinforcement modeling: Only the main cable was modeled. It was embedded, using membrane type elements. Undercarriage: UC components were simulated using Beam and Hinge type connectors. 13

15 Modeling and Pre-processing Boundary Conditions: Tension in the track was achieved by fixing one end of the track, and pulling the other (free) end. Proper *CONTACT, *TIE, *EMBEDDED, *CONSTRAINT definitions were applied. Load Conditions: A weight, equivalent to normal vehicle conditions, of 120,000-N was used. The rolling step was done using implicit dynamics, in a 1-sec simulation. 14

16 FEA simulation of test 15

17 Solution and Post-processing Pressure Distribution: The contour plot (CPRESS) shows the contact pressure at the tread surfaces. It can be clearly seen the area at which the midrollers pass by and the region upon which they offer no influence. Displacement Distribution: The transverse nodal displacement at the contact surfaces (CSLIP1) clearly show two areas where there are two regions of motion 16

18 Validation of computer model TekScan: Pressure mapping of the treads with respect the concrete floor were performed using Tekscan instrumentation product. Conclusion: the pressure distributions found on Tekscan are very similar to those generated by the FEA model. The magnitudes of these pressure are somewhat higher than the computer model 17

19 Presentation Outline - Discussion and Conclusion 18

20 Discussion and Conclusion The Experimental analysis showed us that the two clearly defined areas of wear are mostly due to an intrinsic relationship between the contact pressure and the contact displacements suffered at the surface treads. Microscopic inspection told us that both areas suffered two different mechanism of wear. The severe wear is believed to be a product of surface fatigue of repeated-cycle deformations, and the less worn area produced largely from abrasion. It is seems that the combination of repeated large transverse displacements with low pressure distribution causes the contact region to wear at higher rates than at the areas of high pressure. The FEA model replicated the mechanisms found in the experimental test and it can be used for subsequent simulations to reduce the effects of the abnormal wear development. For future applications: Adding the bias reinforcement, using different friction coefficients could provide with more accurate results. Study the effects of pressure and contact displacement at the idlers. 19

21 Presentation Outline - Questions 20

22 Camoplast Solideal Inc. All rights reserved.