Numerical and experimental impact analysis of square crash box structure with holes
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The document summarizes a thesis defense presentation on the numerical and experimental impact analysis of square crash box structures with holes. The presentation covers: 1) An introduction outlining the research background and objectives on studying crashworthy lightweight vehicle structures. 2) A theoretical analysis of axial crushing mechanisms and modeling of the square columns as thin-walled structures in LS-DYNA using explicit finite element methods. 3) Results showing good agreement between numerical and experimental crushing force curves and parameters for columns with different hole diameters and numbers of holes.
Numerical and experimental impact analysis of square crash box structure with holes
- 1. Thesis Defence Numerical and Experimental Impact Analysis of Square Crash Box Structure with Holes By: Sahril Afandi Sitompul 23611004 Supervisors: Dr. Tatacipta Dirgantara Dr. Leonardo Gunawan Prof. Dr. Ichsan S. Putra Lightweight Structure Research Group Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Jl. Ganesha 10 Bandung 40132, INDONESIA
- 2. Presentation Outline Introduction • Research Background • Research Objectives • Scope of works • Methodology Axial Crushing • Theoretical Analysis Finite Element Methods • Computational Mechanics •Explicit Finite Element Method • Structural Model • Modeling Procedure Experimental Tests • Tensile Testing • Dynamic Axial Crushing Testing Result and Analysis • Numerical and Experimental Results Conclusions and Future Works Lightweight Structure Laboratory Structural Impact Engineering
- 3. Introduction Research Background Auto Motor und Sport spezial 1992, photo H.P. Seufert Lightweight Structure Laboratory Structural Impact Engineering
- 4. Introduction Research Background T. Frank and K. Gruber. Numerical simulation of frontal impact and offset J. Marsolek and H. G. Reimerdes. Energy absorption of metallic cylindrical shells with induced non- collisions.Cray Research Inc., CRAY Channels: 2–6, 1992. axisymmetric folding patterns. International Journal of Impact Engineering 30 (2004) 1209-1223. Lightweight Structure Laboratory Structural Impact Engineering
- 5. Introduction Research Background Lightweight Structure Research Group Concentrating on one of Crashworthiness Safety research areas: STRUCTURAL IMPACT PRESERVES SUFFICIENT SURVIVAL SPACE around the ENGINEERING occupants to limit bodily injury during an accident. CONTROLLING THE DECELERATION within an acceptable safety level to prevent the injury to the passenger. Lightweight Structure Laboratory Structural Impact Engineering
- 6. Introduction Research Objectives To study the behavior of extruded aluminum thin-walled columns with square cross-section and to examine the EFFECT OF INSERTING OF CIRCULAR HOLE(S) as a crush initiator subjected to impact loading Crashworthy Meet acceptable Light-weight vehicle Peak Crushing safety level structure Performance Load Crushing Crushing Force Crash box Parameters Efficiency design Reduce fuel consumption Mean Crushing Reduce CO2 Force emissions Lightweight Structure Laboratory Structural Impact Engineering
- 7. Introduction Scope of Works • The numerical and experimental analysis are limited to a square column with cross section 38 x 38 mm and thickness 1.15 mm subjected to axial impact load with initial velocity below 4.5 m/s. • In parametric study, the column width is varied from 40 to 80 mm with uniform thickness of 1.2 mm. The impact velocity is 4.5 m/s. • The material used in this work was the aluminum extrusion AA 6063-T1. •The holes inserted on the column have the diameter to column width ratios ranged from 0 – 0.8. Lightweight Structure Laboratory Structural Impact Engineering
- 8. Introduction Methodology Axial Crushing of Square Crash Box Experimental Numerical Tensile Testing Parametric Study Axial Crushing Testing Numerical and Experimental Analysis Conclusions and Future Works Lightweight Structure Laboratory Structural Impact Engineering
- 9. Axial Crushing Theoretical Analysis Loading Thin-Walled Structures Material Independent of Strain Rate Axial Crushing Column Dependent of Strain Rate Static Progressive Buckling Low Velocity (up to 10 m/s) Dynamic Progressive Buckling High Velocity Dynamic Plastic Buckling Lightweight Structure Laboratory Structural Impact Engineering N Jones. Structural Impact. 2003. Ly Hung Anh. 2007.
- 10. Axial Crushing Theoretical Analysis Folding Mechanism of Square Column Annisa Jusuf. 2012. Super folding Element. Inextensional mode plastic deformation. Lightweight Structure Laboratory Structural Impact Engineering
- 11. Axial Crushing Theoretical Analysis 60 Pmax Instantaneous Crushing Force Curve MEAN CRUSHING FORCE Instantaneous Crushing Force, P (kN) Mean Crushing Force Curve MAXIMUM PEAK CRUSHING 40 FORCE Pm CRUSHING FORCE EFFICIENCY 20 0 0 20 40 60 80 100 Crushing Length, (mm) Lightweight Structure Laboratory Structural Impact Engineering
- 12. Finite Element Methods Computational Mechanics NANOMECHANICS & MICROMECHANICS SOLID MECHANICS CONTINUUM MECHANICS FLUID MECHANICS (CFD) SYSTEMS FLUID-STRUCTURE INTERACTION (FSI) DISCRETIZATION FINITE ELEMENT METHOD (FEM) SPATIAL BOUNDARY ELEMENT METHOD (BEM) FINITE DIFFERENCE METHOD (FDM) FINITE VOLUME METHOD (FVM) EXPLICIT SMOOTHED PARTICLE HYDRODYNAMICS FINITE ELEMENT (SPH) METHODS TIME EXPLICIT IMPLICIT Lightweight Structure Laboratory Structural Impact Engineering
- 13. Finite Element Methods Explicit Finite Element Methods Used in LS-DYNA commercial code Non-iterative Formulations Small time step (conditional stability) Finite Element Steps Increment 1 Increment 2 Lightweight Structure Laboratory Structural Impact Engineering
- 14. Finite Element Methods Structural Model Impact Impac Number b (mm) t (mm) D/b Velocity t Mass of Holes (m/s) (kg) Set 1 (Experimental and Numerical ) 0 4.3684 0.3 4.3751 38 1.15 1 45.5 0.5 4.4538 0.7 4.3824 Set 2 (Experimental and Numerical ) 0.2 4.3812 45.5 38 1.15 0.3 2 4.3602 0.5 4.4024 Set 3 (Numerical ) 40, 0,0.1, Lightweight Structure Laboratory 50,…,80 …,0.8 Structural Impact4.5 1&2 Engineering 80
- 15. Finite Element Methods Modeling Procedure FINITE ELEMENT MODEL OF THE COLUMN IMPACTING mass 1 The impactor was modeled as a rigid body using hexahedral eight-node solid rigid element HOLE location VELOCITY 2 The hole was introduced in the column model to achieve a stable deformation Impact Velocity direction mode and reduce initial peak load during loading 4 3 BOUNDARY condition The column was fixed in all directions, the constraints are located on every nodes from the lower end of the 5 columns to 12 mm above to simulate the lower jig in the COLUMN wall experiment The column was fully modeled using The impactor was constrained in all direction except quadrilateral Belytscko-Tsay four-nodes shell along the vertical axis which coincides with the direction elements with size 1 mm x 1 mm of the impact in order to ensure the impacting mass did not rotate during impact Lightweight Structure Laboratory Structural Impact Engineering
- 16. Experimental Tests Tensile Testing High Speed Material Testing Machine for INTERMEDIATE STRAIN RATE TENSILE TEST (strain rate 1/s, 10/s, 100/s) INSTRON 5585 for QUASI-STATIC TENSILE TEST (strain rate 0.001/s, 0.1/s) The behavior of AA 6063-T1 is INDEPENDENT OF THE STRAIN RATE Engineering Stress – Strain Curve Mechanical Properties of AA 6063 T1 160 AA 6063-T1 Young’s modulus, E (MPa) 7.32.104 Stress, σ (MPa) 120 Yield stress, y (MPa) 83.81 80 Tensile stress, u (MPa) 154 40 Poisson’s ratio, 0.3 Density, (kg/mm3) 2.7×10–6 0 0 0.02 0.04 0.06 0.08 0.1 0.12 Lightweight Structure Laboratory Structural Impact Engineering Strain, ε
- 17. Experimental Tests Dynamic Axial Crushing Testing Hoist Clamp DROP WEIGHT IMPACT TESTING Wheel MACHINE SPECIFICATIONS : Frame Weightening mass Max. Impact Mass 150 kg Impactor head Max. Impact Height 5m Guide column Speed sensor Max. Impact Velocity 9.8 m/s Specimen Load cell Steel plate Concrete base DAQ Data acquisition Schematic drawing and picture of equipment dropped weight impact testing machine in the Computer Lightweight Structure Laboratory, Faculty of Mechanical and Aerospace Engineering Institut Teknologi Bandung Lightweight Structure Laboratory Structural Impact Engineering
- 18. Experimental Tests Dynamic Axial Crushing Testing Crushing Force History Provide the output Convert a physical Adjust the signal signal representing DAQ NI USB- property change into type and range of the the measurement in 6211, Sampling Rate an electrical signal output a digital code 250 kHz Wheatstone Bridge Strain Gage Lightweight Structure Laboratory Structural Impact Engineering
- 19. Experimental Tests Dynamic Axial Crushing Testing Displacement History Trapezoidal Integration rule applied Lightweight Structure Laboratory Structural Impact Engineering
- 20. Result and Analysis Square Tubes with One Hole COLLAPSE DEFORMATION MODES INSTANTANEOUS CRUSHING FORCE 25 Experimental Crushing Force, P (kN) 20 Experimental (smoothing) Numerical 15 10 5 0 0 10 20 30 40 50 60 70 square crash box with D/b = 0 (without hole) Crushing Length, (mm) 25 Experimental Crushing Force, P (kN) 20 Experimental (smoothing) Numerical 15 Hole 10 location 5 0 square crash box with D/b = 0.3 0 10 20 30 40 50 60 Crushing Length, (mm) Lightweight Structure Laboratory Structural Impact Engineering
- 21. Result and Analysis Square Tubes with One Hole 10 30 10 30 Mean Crushing Force, Pm (kN) Peak Crushing Force, P Max Mean Crushing Force, Pm (kN) Peak Crushing Force, P Max 8 8 25 25 20 20 6 6 (kN) 15 15 (kN) 4 4 Experimental Experimental 10 10 Experimental Experimental 2 2 Numerical Numerical 55 Numerical Numerical 0 0 00 0 0 0.20.2 0.40.4 0.60.6 0.80.8 00 0.20.2 0.4 0.4 0.6 0.6 0.8 0.8 D/b D/b D/b D/b 0.5 Crushing Force Efficiency, CFE 0.4 Experimental Numerical 0.3 D/b Pm Pmax CFE Pm Pmax CFE (kN) (kN) (kN) (kN) 0.2 Experimental Experimenta 0 8.09 24.45 0.33 6.78 18.62 0.36 0.1 l Numerical 0.3 8.24 22.60 0.36 6.62 17.76 0.37 0.5 7.63 21.55 0.35 6.76 16.39 0.41 0 0.7 7.84 22.88 0.34 6.19 14.67 0.42 0 0.2 0.2 0.4 0.4 0.6 0.6 0.8 0.8 D/b D/b Lightweight Structure Laboratory Structural Impact Engineering
- 22. Result and Analysis Square Tubes with Two Holes COLLAPSE DEFORMATION MODES INSTANTANEOUS CRUSHING FORCE 25 Experimental 20 Experimental (smoothing) Crushing Force, P (kN) Numerical 15 10 Hole location 5 0 0 10 20 30 40 50 60 70 Crushing Length, (mm) square crash box with D/b = 0.2 Lightweight Structure Laboratory Structural Impact Engineering
- 23. Result and Analysis Square Tubes with Two Holes 30 10 Peak Crushing Force, P Max (kN) Mean Crushing Force, Pm (kN) 25 8 20 6 15 4 Experimental 10 Experimental 2 Numerical 5 Numerical 0 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0 0.1 0.2 0.3 0.4 0.5 0.6 D/b D/b 0.5 Crushing Force Efficiency, CFE Experimental Numerical 0.4 D/b Pm Pmax CFE Pm Pmax CFE 0.3 (kN) (kN) (kN) (kN) 0.2 Experimental 0 8.09 24.45 0.33 6.78 18.62 0.36 0.1 Numerical 0.2 7.71 22.63 0.34 6.29 17.79 0.35 0 0.3 7.72 21.43 0.36 6.34 17.21 0.37 0 0.1 0.2 0.3 0.4 0.5 0.6 D/b 0.5 7.59 19.55 0.39 6.40 15.29 0.42 Lightweight Structure Laboratory Structural Impact Engineering
- 24. Result and Analysis Parametric Study Square Columns with One Hole 25 D/b = 0 Instantaneous Crushing Force, P (kN) D/b = 0.2 20 D/b = 0.3 D/b = 0.4 D/b = 0.5 15 D/b = 0.6 D/b = 0.7 D/b = 0.8 10 5 0 0 20 40 60 80 100 120 140 Displacement, mm Deformation modes of square crash box with b = 40: (a) D/b = 0.3; (b) D/b = 0.4. Lightweight Structure Laboratory Structural Impact Engineering
- 25. Result and Analysis Parametric Study Square Columns with One Hole 12 60 b = 40 Peak Crushing Force, P Max Mean Crushing Force, Pm (kN) b = 50 10 50 b = 60 8 40 b = 70 b = 80 6 30 (kN) b = 40 4 b = 50 20 b = 60 2 b = 70 10 b = 80 0 0 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 D/b D/b 0.5 Crushing Force Efficiency, CFE 0.4 0.3 b = 40 0.2 b = 50 b = 60 0.1 b = 70 b = 80 0 0 0.2 0.4 0.6 0.8 1 D/b Lightweight Structure Laboratory Structural Impact Engineering
- 26. Result and Analysis Parametric Study Square Columns with Two Holes 25 D/b = 0 Instantaneous Crushing Force, P (kN) D/b = 0.2 20 D/b = 0.3 D/b = 0.4 D/b = 0.5 15 D/b = 0.6 D/b = 0.7 D/b = 0.8 10 5 0 0 20 40 60 80 100 120 140 Displacement, mm Deformation modes of square crash box with b = 50: (a) D/b = 0.3; (b) D/b = 0.5. Lightweight Structure Laboratory Structural Impact Engineering
- 27. Result and Analysis Parametric Study Square Columns with Two Holes 60 b = 40 12 Peak Crushing Force, P Max (kN) Mean Crushing Force, Pm (kN) b = 50 10 50 b = 60 40 b = 70 8 b = 80 6 30 b = 40 4 b = 50 20 2 b = 60 b = 70 10 0 b = 80 0 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 D/b D/b 0.5 Crushing Force Efficiency, CFE 0.4 0.3 0.2 b = 40 b = 50 0.1 b = 60 b = 70 0 b = 80 0 0.2 0.4 0.6 0.8 1 Lightweight Structure Laboratory D/b Structural Impact Engineering
- 28. Conclusions and Future Works Conclusions • The numerical simulation can predict the deformation mode compared to the experiment results. • It is found that inserting holes in a square box column will decrease the peak crushing force and increase the CFE of the column. Lightweight Structure Laboratory Structural Impact Engineering
- 29. Conclusions and Future Works Future Works • Perform numerical and experimental analysis to obtain a higher value of CFE with different geometrical configurations and location of the discontinuities. • Perform numerical and experimental analysis to study the effect of discontinuities for different material properties. Lightweight Structure Laboratory Structural Impact Engineering
- 30. Thank You Lightweight Structure Laboratory Structural Impact Engineering