Simple analysis of stress on pelvic muscle while riding a bicycle.

We all have ridden a bicycle in some part of our life. If you have done it after a long gap, you may have experienced some pain in the pelvic muscle. After last cycling tour to Nagarkot, I did some analysis to find the stress on the seats of bicycle while cycling. The analysis was done in staad.pro. The analysis file is given below. The analysis is crude and even do not consider pretension force on the spokes.

The result shows that the pain is critical just below the seat where the load is transferred to the frame of bicycle. With mass of 70kg (applied by dividing it to the nodes of seat and the handles) the maximum stress was about 4Mpa. This stress was enough to give pain in the ass! 😉

STAAD SPACE DXF Import of cycle.dxf START JOB INFORMATION ENGINEER DATE 18-Dec-11 JOB NAME analysis of bicycle ENGINEER NAME nirmal END JOB INFORMATION INPUT WIDTH 79 UNIT METER KN JOINT COORDINATES 1 32.6598 28.8503 0; 2 32.4896 29.2262 0; 3 32.3713 29.1453 0; 4 32.2879 29.0288 0; 5 32.2492 28.8909 0; 6 32.2602 28.748 0; 7 32.3193 28.6175 0; 8 32.4194 28.515 0; 9 32.5486 28.4531 0; 10 32.6912 28.439 0; 11 32.83 28.4745 0; 12 32.9483 28.5554 0; 13 33.0318 28.6719 0; 14 33.0704 28.8098 0; 15 33.0595 28.9527 0; 16 33.0004 29.0832 0; 17 32.9002 29.1856 0; 18 32.771 29.2476 0; 19 32.6284 29.2617 0; 20 34.4598 28.8503 0; 21 34.2896 29.2262 0; 22 34.1713 29.1453 0; 23 34.0879 29.0288 0; 24 34.0492 28.8909 0; 25 34.0602 28.748 0; 26 34.1193 28.6175 0; 27 34.2194 28.515 0; 28 34.3486 28.4531 0; 29 34.4912 28.439 0; 30 34.63 28.4745 0; 31 34.7483 28.5554 0; 32 34.8318 28.6719 0; 33 34.8704 28.8098 0; 34 34.8595 28.9527 0; 35 34.8004 29.0832 0; 36 34.7002 29.1856 0; 37 34.571 29.2476 0; 38 34.4284 29.2617 0; 39 32.8993 29.8509 0; 40 33.5598 28.8503 0; 41 33.8437 29.5157 0; 42 32.8181 29.5116 0; 43 33.8437 29.8 0; 44 32.8993 29.8509 0.3; 45 32.8993 29.8509 -0.3; 46 33.9437 29.8 0; 47 33.7437 29.8 0; 48 33.7437 29.8 0.0201266; 49 33.9437 29.8 0.05; 50 33.7437 29.8 -0.02; 51 33.9437 29.8 -0.05; 52 33.913 29.8 -0.0220038; 53 33.9037 29.8 -0.0439999; 54 33.9037 29.8 0; 55 33.7837 29.8 -0.0259996; 56 33.7837 29.8 0; 57 33.8237 29.8 0; 58 33.9213 29.8 -0.0174479; 59 33.9437 29.8 -0.02; 60 33.9437 29.8 -0.03; 61 33.936 29.8 -0.0375694; 62 33.9216 29.8 -0.0354397; 63 33.9437 29.8 -0.04; 64 33.9265 29.8 -0.00939203; 65 33.8637 29.8 -0.0379998; 66 33.8637 29.8 0; 67 33.8237 29.8 -0.0319997; 68 33.7635 29.8 -0.00723009; 69 33.7761 29.8 -0.0130071; 70 33.7463 29.8 -0.0070937; 71 33.753 29.8 -0.0137868; 72 33.7437 29.8 -0.012; 73 33.7649 29.8 -0.0155657; 74 33.7437 29.8 -0.004; 75 33.9437 29.8 -0.01; 76 33.7437 29.8 -0.016; 77 33.7437 29.8 -0.008; 78 33.9174 29.8 0.0226593; 79 33.9037 29.8 0.0440258; 80 33.7837 29.8 0.0261014; 81 33.8237 29.8 0.0320762; 82 33.9316 29.8 0.0271502; 83 33.9437 29.8 0.02; 84 33.9256 29.8 0.0114676; 85 33.9369 29.8 0.0367192; 86 33.924 29.8 0.0358658; 87 33.8637 29.8 0.038051; 88 33.7466 29.8 0.0132581; 89 33.7437 29.8 0.0161013; 90 33.757 29.8 0.0110781; 91 33.7743 29.8 0.0111249; 92 33.7483 29.8 0.00788722; 93 33.7437 29.8 0.00805063; 94 33.7437 29.8 0.0120759; 95 33.9437 29.8 0.01; 96 33.9437 29.8 0.03; 97 33.7437 29.8 0.00402531; 98 33.9437 29.8 0.04; MEMBER INCIDENCES 1 1 2; 2 1 3; 3 1 4; 4 1 5; 5 1 6; 6 1 7; 7 1 8; 8 1 9; 9 1 10; 10 1 11; 11 1 12; 12 1 13; 13 1 14; 14 1 15; 15 1 16; 16 1 17; 17 1 18; 18 1 19; 19 20 21; 20 20 22; 21 20 23; 22 20 24; 23 20 25; 24 20 26; 25 20 27; 26 20 28; 27 20 29; 28 20 30; 29 20 31; 30 20 32; 31 20 33; 32 20 34; 33 20 35; 34 20 36; 35 20 37; 36 20 38; 37 1 42; 38 40 20; 39 20 41; 40 41 42; 41 40 42; 42 40 41; 43 41 43; 44 39 44; 45 39 45; 46 43 66; 47 43 57; 48 48 80; 49 50 55; 50 51 63; 51 50 76; 52 2 19; 53 19 18; 54 18 17; 55 17 16; 56 16 15; 57 15 14; 58 14 13; 59 13 12; 60 12 11; 61 11 10; 62 10 9; 63 9 8; 64 8 7; 65 7 6; 66 6 5; 67 5 4; 68 4 3; 69 3 2; 70 21 38; 71 38 37; 72 37 36; 73 36 35; 74 35 34; 75 34 33; 76 33 32; 77 32 31; 78 31 30; 79 30 29; 80 29 28; 81 28 27; 82 26 25; 83 27 26; 84 25 24; 85 24 23; 86 23 22; 87 22 21; 90 42 39; 91 53 51; 92 54 46; 94 55 67; 95 56 47; 96 57 56; 98 59 75; 99 60 59; 102 63 60; 106 65 53; 108 66 54; 110 67 65; 114 72 77; 129 74 97; 132 75 95; 135 76 72; 138 77 74; 145 79 49; 147 80 81; 148 81 87; 150 83 96; 156 87 79; 161 89 48; 174 93 94; 175 94 89; 179 95 83; 182 96 98; 185 97 93; 190 98 49; ELEMENT INCIDENCES SHELL 93 52 53 54; 97 55 56 57; 100 58 59 60; 101 61 62 58; 103 61 63 51; 104 64 58 54; 105 58 52 54; 107 54 53 65; 109 66 54 65; 111 66 65 67; 112 57 66 67; 113 68 56 69; 115 70 71 72; 116 70 68 71; 117 68 69 73; 118 73 69 55; 119 69 56 55; 120 55 57 67; 121 62 53 52; 122 58 62 52; 123 68 47 56; 124 71 68 73; 125 62 51 53; 126 61 51 62; 127 71 73 50; 128 73 55 50; 130 70 74 47; 131 70 47 68; 133 64 75 59; 134 64 59 58; 136 71 76 72; 137 71 50 76; 139 70 77 74; 140 70 72 77; 141 61 60 63; 142 61 58 60; 143 64 46 75; 144 64 54 46; 146 78 54 79; 149 80 81 57; 151 82 83 84; 152 85 82 86; 153 84 54 78; 154 82 78 86; 155 86 78 79; 157 87 79 54; 158 87 54 66; 159 81 87 66; 160 81 66 57; 162 88 89 48; 163 90 80 91; 164 92 90 47; 165 90 91 47; 166 91 56 47; 167 91 80 56; 168 56 80 57; 169 84 46 54; 170 82 84 78; 171 90 48 80; 172 88 90 92; 173 88 48 90; 176 92 93 94; 177 85 86 49; 178 86 79 49; 180 84 95 46; 181 84 83 95; 183 82 96 83; 184 85 96 82; 186 92 97 93; 187 92 47 97; 188 88 94 89; 189 88 92 94; 191 85 98 96; 192 85 49 98; ELEMENT PROPERTY 93 97 100 101 103 TO 105 107 109 111 TO 113 115 TO 128 130 131 133 - 134 136 137 139 TO 144 146 149 151 TO 155 157 TO 160 162 TO 173 176 - 177 TO 178 180 181 183 184 186 TO 189 191 192 THICKNESS 0.05 DEFINE MATERIAL START ISOTROPIC STEEL E 2.05e+008 POISSON 0.3 DENSITY 76.8195 ALPHA 1.2e-005 DAMP 0.03 ISOTROPIC CONCRETE E 2.17185e+007 POISSON 0.17 DENSITY 23.5616 ALPHA 1e-005 DAMP 0.05 ISOTROPIC ALUMINUM E 6.89476e+007 POISSON 0.33 DENSITY 26.6018 ALPHA 2.3e-005 DAMP 0.03 END DEFINE MATERIAL MEMBER PROPERTY 37 TO 45 90 PRIS ROUND STA 0.04 END 0.04 THI 0.002 1 TO 36 46 TO 51 91 92 94 TO 96 98 99 102 106 108 110 114 129 132 135 - 138 145 147 148 150 156 161 174 175 179 182 185 190 PRIS YD 0.01 52 TO 87 PRIS YD 0.01 ZD 0.05 CONSTANTS MATERIAL STEEL MEMB 37 TO 45 52 TO 87 90 MATERIAL CONCRETE MEMB 1 TO 36 46 TO 51 91 92 94 TO 96 98 99 102 106 - 108 110 114 129 132 135 138 145 147 148 150 156 161 174 175 179 182 - 185 190 MATERIAL ALUMINUM MEMB 93 97 100 101 103 TO 105 107 109 111 TO 113 - 115 TO 128 130 131 133 134 136 137 139 TO 144 146 149 151 TO 155 157 - 158 TO 160 162 TO 173 176 TO 178 180 181 183 184 186 TO 189 191 192 SUPPORTS 10 29 PINNED LOAD 1 LOADTYPE None TITLE weight SELFWEIGHT Y -1 JOINT LOAD 43 TO 98 FY -0.07 PERFORM ANALYSIS PRINT ALL FINISH

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