1 Using FE to simulate the effect of tolerance on part deformation By I A Manarvi & N P Juster University of Strathclyde Department of Design Manufacture and Engineering Management

2 Outline Introduction Methodology Experimental phase Procedure Tolerance Vs. deformation experimental results FE simulations Tolerance Vs. deformation FE results FE deformation pattern at tolerance values Comparison of Experimental and FE results Conclusions

3 Introduction Tolerance Allocation in Product Design: a) Vital activity for mass production and interchange- ability of parts b) Required during design, Manufacturing, Assembly, Quality and performance evaluation phases. l Major influences on function, cost, customer requirements and aesthetics. Scope : Investigating use of FE simulations as a tool to verify influence of tolerance on part deformation at initial design stages

4 Methodology Experimental phase: a) Selection of specific type of tolerance, a simplified geometry and commonly used material b) Design and manufacturing of a test rig for experiments simulating tolerance conditions. l Execution of experiments and collection of data FE simulation phase: a) FE modelling and simulation with ABAQUS software with similar boundary conditions as experiments. b) Collection of FE results at same Axis location as of experimental data

5 Known Parameters: a) Selection of tolerance: Location of two hole centres b) Simplified geometry: Rectangular strip 200 x 40 x 1 mm c) Material : ABS plastics ( Astyrn BR 712 A) Test rig designed and manufactured: Base Platform Parallel Precision slides Side supports Sliding platform Rotary Knob Dial Indicator 1 Dial Indicator 2 Dial Indicator 3 Experimental Phase

6 Procedure Specimen Rotary knob Pin B (0.2, 0.4, 0.6, 0.8, 1.0, 1.2mm) Pin A (Fixed) Z Y X Y Z Dial Indicator 1 for tolerance measurement Dial Indicator 2,3 for side deflection measurement Out of plane deformation Z axis

7 Tolerance vs. Deformation Experimental Results

8 FE simulations Material properties: ABS plastics ( Astyrn BR 712 A) Material type = Elastic Young’s Modulus = 106 e 3 MPa Poison’s ratio = 0.39 Analysis steps : Initial & Step 1 with assumptions as: Non linear geometries ON Buckling criteria = Static Riks Model creation: Rectangular strip 200 x 40 x 1 mm

9 FE Simulations Boundary conditions: Y X Z Pin B Pin A Ux = 0.0 Uy = 0.0 Uz = 0.0 Rx = 0.0 Ry = 0.0 Rz = 0.0 Ux =Free Uy =Free Uz =Free Rx =Free Ry =Free Rz =Free Pin B would move in steps to 0.2, 0.4, 0.6, 0.8, 1.0, 1.2 mm in X-axis Meshing conditions: Mesh seeds = 2mm Elements = Hexagon

10 Tolerance vs. Deformation FE Results

11 FE Deformation Pattern of Model at Different Tolerance values 0.2 mm 0.4 mm 0.6 mm 0.8 mm 1.0 mm

12 Comparison of Experimental and FE Deformation at 0.2, 0.4 & 0.6mm

13 Comparison of Experimental and FE Deformation at 0.8, 1.0 & 1.2mm

14 FE Analysis of complex geometry IDEAS VISUALISER FEM 1 B.C. 1, DISPLACEMENT_1, RESTRAINT SET 1 DISPLACEMENT Magnitude Un averaged Top Shell Min: 0.00 mm Max: 2.07 mm X Y Z Y= 1.0mm Rest all DOF set free All DOF constrained All DOF free

15 FE Analysis of complex geometry Hole C Y= 1.0mm Rest all DOF set free All DOF constrained in Hole A All DOF constrained in Hole B IDEAS FEM 1 B.C. 1, DISPLACEMENT_1 RESTRAINT SET 1 ELEMENT SIZE = 0.2mm Type: Thin shell 2.5mm thickness No. of Elements = Over 400,000 Hole D No constrain applied X Z Y

16 FE Analysis of complex geometry mm Un deformed model Deformed model No deformation Zone Maximum deformation Zone due to 1.0mm tolerance Deformed model Un deformed model

17 FE Analysis of complex geometry IDEAS FEM 1 B.C. 1, DISPLACEMENT_1 RESTRAINT SET 1 ELEMENT SIZE = 2.5mm Type: Thin shell 2.5mm thickness No. of Elements = Over 400,000 Y= 1.0mm Rest all DOF set free All DOF constrained No constrain applied Y Z Y SIDE VIEW FRONT VIEW X

18 FE of Automotive Glove box IDEAS VISUALISER FEM 1 FRONT VIEW B.C. 1, DISPLACEMENT_1, RESTRAINT SET 1 DISPLACEMENT Magnitude un averaged Top Shell Min: 0.00 mm Max: 3.86 mm mm Max. deformation No deformation

19 Conclusions l Peak deformation at center of specimen reducing towards edges. l FE and experimental results showed tolerance leading to deformation subsequently influencing part assembly l Existence of a linear relationship between tolerance and deformation of parts confirmed by FE and experiments l Similarity of experimental and FE results signified the possibility of using FE as a tool for tolerance allocation.

20 Thank You for attention Questions ?