Compression Sportswear Using 3D-CG Human Model
3-dimensional joint torque calculation of compression sportswear using 3D-CG human model
• Akihiro Matsuda, University of Tsukuba • Hirokazu Tanaka , University of Tsukuba • Hitoshi Aoki, University of Tsukuba • Takatsugu Shimana, Mizno Corp. Introduction • Mechanical effect of compression wear to human body is important design issues • Measurement of stress distribution of compression wear in dynamic motion is difficult • One concept of the design for competitive swimwear is to keep the flat body • One concept of the design for compression sportswear is to support knee joint
2 Objective
Our purpose is to develop numerical methods • To visualize force and deformation of swimwear and compression sportswear • To calculate joint torque generated by swimwear and compression sportswear
3 Compression Sportswear
• Current compression wear and swimwear are made of chemical fiber • Show high extensibility and anisotropy – Can compress and deform human body – But, it shows different stiffness on tensile direction
σ Warp
Hard soft
ε Weft Hard 4 Compression Sportswear
• Current competitive swimwear are made of chemical fiber • They shows stress softening ̶ Shows softening according to the experienced maximum elongation
For example, we tensile sportswear material as elongations correspond to 1.6, 1.7 and 1.8. They shows stress softening.
1.6 1.7 1.8 5 5 Material modeling
6 Anisotropic Hyperelastic Model
• Anisotropic hyperelastic model Represent the mechanical properties by a strain energy function W • Strain energy function W W Give stress by S 2 C We divided W into three parts (1) (2) WTotal WIsotropic W Anisotropic W Anisotropic Anisotropic Hyperelastic Model
• Stress Softening Function Represents the stress softening according to experienced elongation of warp and weft fibers by the following equation Stress softening of warp and weft fibers are represented independently
(1) (1) S(I4 max ) 1111exp11I4 max 1 (2) (2) S(I4 max ) 1221exp 22I4 max 1
( 1 ) ( 2 ) • I 4 max , I 4 max : The experienced elongation
• α11 , α 22 , γ 11 , γ 22 : Material Parameters
8 Anisotropic Hyperelastic Model
• Stress Softening Function • Finally, We propose following potential function to consider • nonlinear anisotropic elasticity • stress softening according to experienced elongation
(1) (1) WTotal WIsotropic S(I4 max )W Anisotropic (2) (2) S(I4 max )W Anisotropic
9 Cyclic Tensile Loading Test • Test specimen • 73% of Nylon and 27% of Polyurethane • 30mm in width 120mm in length 0.20mm in Thickness • Fiber orientation angle θ • θ = 0, 15, 30, 45, 60, 75, 90
• Cyclic tensile test • 5 cycles of tensile loading correspond to stretch of 1.4(40%), 1.5(50%), 1.6(60%), 1.7(70%) and 1.8(80%) were applied to specimens • Loading speed:1.0 mm/sec
10 Comparison with Test Results
0
• Material parameters of theoretical formula were identified using the test results (0°, 45° and 90°)
• Nonlinear anisotropic elasticity and stress-softening are considerable
11 3-Dimensional Computer Graphics of Human Model
12 3-Dimensional Computer Graphics of Human Model • Computer graphical model of human body were prepared to investigate human motions during exercise – Swimming, running • Strain of skins were calibrated by human subjects
3D-CG of human Swimwear model Compression wear model 13 Deformation of Sub-mesh • Assumptions of simulation 1. The swimwear and compression sportswear were fixed to human body 2. Displacement and deformation of sub-mesh were same as 3- dimensional human model (friction is not considered) 3. 140% of stretch in horizontal direction and 120% in vertical direction were applied as initial stretch
14 Stress Calculation Result: Crawl
MPa 1.8
1.4
1.1
0.7
0.4
0 • One cycle motion was represented by 3D-CG images of 45 sheets • Maximum Cauchy stress in length direction are plotted • Reproduced that maximum Cauchy stress in left and right half were alternately increased
15 Calculation Result: Butterfly
MPa 1.8
1.4
1.1
0.7
0.4
0 • Butterfly motion was represented by 33 sheets of 3D-CG images • Reproduced that maximum Cauchy stress in left and right half were symmetric
16 Calculation Results: Running
• High stress distribution were found around hip and knee joints
17 Evaluation of Hip Joint Torque • Calculate hip joint torque of crawl using the following equation N T W R F i1 i i i
Ri : Position vector of each node from the hip joint
F i : Load vector of each node Weight function to hip torque Wi :
Positive torque
18 Torque Calculation Results: Crawl
• Hip joint torques in crawl were plotted • Positive value mean extension torque • Wearing this swimwear gives us extensional support 19 Effect of Initial Stretch on Hip Joint Torque
5 5 m] 4 Hip joint Hip joint
m]
・ 4
・ 3 3
2 2
1 1
Average torque [N 0 Average torque [N 0 1.0 1.1 1.2 1.3 1.4 1.5 1.0 1.1 1.2 1.3 1.4 1.5 Initial nominal stretch of width direction Initial nominal stretch of body length direction
• Hip joint torques were calculated with different initial stretch in width and length direction to evaluate the effect of “wearing” the swim wear • Initial stretch in horizontal(width) direction is effective to produce better support 20 Effect of Fiber Orientation Angle on Hip Joint Torque
5 Hip joint m] 4
・
3
2
1
Average torque [N 0 0 30 60 90 120 150 180 Fiber orientation angle [ º]
• Effect of fiber orientation angle on hip joint torque was possible to calculate by proposed anisotropic model • Fiber orientation angle between 150 to 180 degree show better support to keep flat body 21 Conclusion
• Stress distribution and hip joint torque were calculated using the combination of the proposed material model and 3-dimensional computational graphic model.
• From the cyclic tensile loading test of sportswear, an anisotropic material modeling was proposed.
• From numerical simulation, some design key-points like hip joint torque from swimwear and knee support function of compression wear were investigated.
• Now, we working on evaluation of knee joint torque given by compression sportswear to calibrate our simulation method.
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