# BEAM32R - Strange internal energy values **URL:** \ **Category:** Uncategorized\ **Created:** [May 6, 2025, 1:39pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731 "2025-05-06T13:39:51Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![cellini](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cellini](https://calculix.discourse.group/u/cellini)\ **Post date:** [May 6, 2025, 1:39pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/1 "2025-05-06T13:39:51Z")
Hi everyone I am testing a beam structure under compressione and i am finding some issues in the internal energy extraction. I am performing a NL analysis and the internal energy measured for the elements is in a quite strange format. Something like this: 1 3.833492-313 2 3.699148-313 3 1.197441-312 4 7.086744-313 The other outputs are good (displacements and stresses). I also find issues when i try to extract the volume from the model. Same type of values. Does anyone know the possible reason for that? The .inp is the following \*HEADING Model: PROVABYME1.inp Date:2025-05-06 \*NODE,NSET=NAll 1, 0.000000, 0.000000, 0.000000 2, 0.000000, 60.000000, 0.000000 3, 0.000000, 120.000000, 0.000000 4, 0.000000, 180.000000, 0.000000 5, 0.000000, 240.000000, 0.000000 6, 0.000000, 300.000000, 0.000000 7, 60.000000, 0.000000, 0.000000 8, 60.000000, 60.000000, 0.000000 9, 60.000000, 120.000000, 0.000000 10, 60.000000, 180.000000, 0.000000 11, 60.000000, 240.000000, 0.000000 12, 60.000000, 300.000000, 0.000000 13, 120.000000, 0.000000, 0.000000 14, 120.000000, 60.000000, 0.000000 15, 120.000000, 120.000000, 0.000000 16, 120.000000, 180.000000, 0.000000 17, 120.000000, 240.000000, 0.000000 18, 120.000000, 300.000000, 0.000000 19, 180.000000, 0.000000, 0.000000 20, 180.000000, 60.000000, 0.000000 21, 180.000000, 120.000000, 0.000000 22, 180.000000, 180.000000, 0.000000 23, 180.000000, 240.000000, 0.000000 24, 180.000000, 300.000000, 0.000000 25, 240.000000, 0.000000, 0.000000 26, 240.000000, 60.000000, 0.000000 27, 240.000000, 120.000000, 0.000000 28, 240.000000, 180.000000, 0.000000 29, 240.000000, 240.000000, 0.000000 30, 240.000000, 300.000000, 0.000000 31, 300.000000, 0.000000, 0.000000 32, 300.000000, 60.000000, 0.000000 33, 300.000000, 120.000000, 0.000000 34, 300.000000, 180.000000, 0.000000 35, 300.000000, 240.000000, 0.000000 36, 300.000000, 300.000000, 0.000000 37, 0.000000, 0.000000, 150.000000 38, 0.000000, 60.000000, 150.000000 39, 0.000000, 120.000000, 150.000000 40, 0.000000, 180.000000, 150.000000 41, 0.000000, 240.000000, 150.000000 42, 0.000000, 300.000000, 150.000000 43, 60.000000, 0.000000, 150.000000 44, 60.000000, 60.000000, 150.000000 45, 60.000000, 120.000000, 150.000000 46, 60.000000, 180.000000, 150.000000 47, 60.000000, 240.000000, 150.000000 48, 60.000000, 300.000000, 150.000000 49, 120.000000, 0.000000, 150.000000 50, 120.000000, 60.000000, 150.000000 51, 120.000000, 120.000000, 150.000000 52, 120.000000, 180.000000, 150.000000 53, 120.000000, 240.000000, 150.000000 54, 120.000000, 300.000000, 150.000000 55, 180.000000, 0.000000, 150.000000 56, 180.000000, 60.000000, 150.000000 57, 180.000000, 120.000000, 150.000000 58, 180.000000, 180.000000, 150.000000 59, 180.000000, 240.000000, 150.000000 60, 180.000000, 300.000000, 150.000000 61, 240.000000, 0.000000, 150.000000 62, 240.000000, 60.000000, 150.000000 63, 240.000000, 120.000000, 150.000000 64, 240.000000, 180.000000, 150.000000 65, 240.000000, 240.000000, 150.000000 66, 240.000000, 300.000000, 150.000000 67, 300.000000, 0.000000, 150.000000 68, 300.000000, 60.000000, 150.000000 69, 300.000000, 120.000000, 150.000000 70, 300.000000, 180.000000, 150.000000 71, 300.000000, 240.000000, 150.000000 72, 300.000000, 300.000000, 150.000000 73, 125.106601, 216.097348, 0.017156 74, 90.699772, 44.026767, 13.850789 75, 55.878063, 103.668218, 59.515121 76, 161.645020, 125.758354, 102.782925 77, 61.335675, 263.435231, 4.108139 78, 201.140253, 125.191441, 83.803474 79, 42.116082, 59.430447, 120.111685 80, 290.478473, 94.027253, 103.848392 81, 262.916746, 268.381999, 12.756632 82, 11.716435, 50.949126, 131.721376 83, 21.058041, 29.715223, 60.055843 84, 5.858217, 25.474563, 65.860688 85, 27.939032, 81.834109, 29.757561 86, 21.058041, 59.715223, 60.055843 87, 5.858217, 55.474563, 65.860688 88, 5.858217, 85.474563, 65.860688 89, 27.939032, 111.834109, 29.757561 90, 27.939032, 141.834109, 29.757561 91, 30.667837, 251.717615, 2.054069 92, 30.667837, 281.717615, 2.054069 93, 75.349886, 22.013384, 6.925395 94, 51.058041, 29.715223, 60.055843 95, 57.939032, 81.834109, 29.757561 96, 51.058041, 59.715223, 60.055843 97, 75.349886, 52.013384, 6.925395 98, 75.349886, 82.013384, 6.925395 99, 57.939032, 111.834109, 29.757561 100, 92.553301, 198.048674, 0.008578 101, 57.939032, 141.834109, 29.757561 102, 92.553301, 228.048674, 0.008578 103, 60.667837, 251.717615, 2.054069 104, 60.667837, 281.717615, 2.054069 105, 105.349886, 22.013384, 6.925395 106, 105.349886, 52.013384, 6.925395 107, 140.822510, 92.879177, 51.391463 108, 87.939032, 81.834109, 29.757561 109, 87.939032, 111.834109, 29.757561 110, 105.349886, 82.013384, 6.925395 111, 140.822510, 122.879177, 51.391463 112, 140.822510, 152.879177, 51.391463 113, 122.553301, 198.048674, 0.008578 114, 87.939032, 141.834109, 29.757561 115, 122.553301, 228.048674, 0.008578 116, 90.667837, 251.717615, 2.054069 117, 90.667837, 281.717615, 2.054069 118, 170.822510, 92.879177, 51.391463 119, 190.570127, 92.595720, 41.901737 120, 170.822510, 122.879177, 51.391463 121, 190.570127, 122.595720, 41.901737 122, 170.822510, 152.879177, 51.391463 123, 190.570127, 152.595720, 41.901737 124, 152.553301, 198.048674, 0.008578 125, 221.458373, 254.191000, 6.378316 126, 190.570127, 182.595720, 41.901737 127, 152.553301, 228.048674, 0.008578 128, 221.458373, 284.191000, 6.378316 129, 265.239236, 47.013627, 51.924196 130, 220.570127, 92.595720, 41.901737 131, 265.239236, 77.013627, 51.924196 132, 220.570127, 122.595720, 41.901737 133, 265.239236, 107.013627, 51.924196 134, 220.570127, 152.595720, 41.901737 135, 265.239236, 137.013627, 51.924196 136, 251.458373, 224.191000, 6.378316 137, 251.458373, 254.191000, 6.378316 138, 220.570127, 182.595720, 41.901737 139, 251.458373, 284.191000, 6.378316 140, 295.239236, 47.013627, 51.924196 141, 295.239236, 77.013627, 51.924196 142, 295.239236, 107.013627, 51.924196 143, 250.570127, 152.595720, 41.901737 144, 295.239236, 137.013627, 51.924196 145, 281.458373, 224.191000, 6.378316 146, 281.458373, 254.191000, 6.378316 147, 281.458373, 284.191000, 6.378316 148, 21.058041, 29.715223, 135.055843 149, 5.858217, 25.474563, 140.860688 150, 5.858217, 55.474563, 140.860688 151, 21.058041, 59.715223, 135.055843 152, 5.858217, 85.474563, 140.860688 153, 27.939032, 111.834109, 104.757561 154, 21.058041, 89.715223, 135.055843 155, 27.939032, 141.834109, 104.757561 156, 30.667837, 251.717615, 77.054069 157, 30.667837, 281.717615, 77.054069 158, 35.858217, 25.474563, 140.860688 159, 51.058041, 29.715223, 135.055843 160, 75.349886, 22.013384, 81.925395 161, 51.058041, 59.715223, 135.055843 162, 35.858217, 55.474563, 140.860688 163, 57.939032, 111.834109, 104.757561 164, 51.058041, 89.715223, 135.055843 165, 57.939032, 141.834109, 104.757561 166, 92.553301, 198.048674, 75.008578 167, 92.553301, 228.048674, 75.008578 168, 60.667837, 251.717615, 77.054069 169, 60.667837, 281.717615, 77.054069 170, 81.058041, 29.715223, 135.055843 171, 105.349886, 22.013384, 81.925395 172, 81.058041, 59.715223, 135.055843 173, 105.349886, 52.013384, 81.925395 174, 140.822510, 92.879177, 126.391463 175, 87.939032, 81.834109, 104.757561 176, 87.939032, 111.834109, 104.757561 177, 81.058041, 89.715223, 135.055843 178, 140.822510, 122.879177, 126.391463 179, 140.822510, 152.879177, 126.391463 180, 122.553301, 198.048674, 75.008578 181, 87.939032, 141.834109, 104.757561 182, 122.553301, 228.048674, 75.008578 183, 90.667837, 251.717615, 77.054069 184, 90.667837, 281.717615, 77.054069 185, 170.822510, 92.879177, 126.391463 186, 190.570127, 92.595720, 116.901737 187, 170.822510, 122.879177, 126.391463 188, 190.570127, 122.595720, 116.901737 189, 170.822510, 152.879177, 126.391463 190, 190.570127, 152.595720, 116.901737 191, 152.553301, 198.048674, 75.008578 192, 152.553301, 228.048674, 75.008578 193, 221.458373, 254.191000, 81.378316 194, 190.570127, 182.595720, 116.901737 195, 221.458373, 284.191000, 81.378316 196, 265.239236, 47.013627, 126.924196 197, 220.570127, 92.595720, 116.901737 198, 265.239236, 77.013627, 126.924196 199, 220.570127, 122.595720, 116.901737 200, 265.239236, 107.013627, 126.924196 201, 220.570127, 152.595720, 116.901737 202, 265.239236, 137.013627, 126.924196 203, 251.458373, 224.191000, 81.378316 204, 251.458373, 254.191000, 81.378316 205, 220.570127, 182.595720, 116.901737 206, 251.458373, 284.191000, 81.378316 207, 295.239236, 47.013627, 126.924196 208, 295.239236, 77.013627, 126.924196 209, 295.239236, 107.013627, 126.924196 210, 281.458373, 224.191000, 81.378316 211, 250.570127, 152.595720, 116.901737 212, 295.239236, 137.013627, 126.924196 213, 281.458373, 254.191000, 81.378316 214, 281.458373, 284.191000, 81.378316 215, 143.375811, 170.927851, 51.400041 216, 73.288918, 73.847493, 36.682955 217, 66.407927, 51.728607, 66.981237 218, 126.172396, 84.892561, 58.316857 219, 108.761542, 114.713286, 81.149023 220, 33.797249, 77.308672, 95.618248 221, 48.997072, 81.549332, 89.813403 222, 181.392637, 125.474898, 93.293200 223, 245.809363, 109.609347, 93.825933 224, 26.916258, 55.189786, 125.916530 \*ELEMENT,TYPE=B32R,ELSET=EAll 1, 1, 83, 79 2, 1, 84, 82 3, 2, 85, 75 4, 2, 86, 79 5, 2, 87, 82 6, 3, 88, 82 7, 3, 89, 75 8, 4, 90, 75 9, 5, 91, 77 10, 6, 92, 77 11, 7, 93, 74 12, 7, 94, 79 13, 8, 95, 75 14, 8, 96, 79 15, 8, 97, 74 16, 9, 98, 74 17, 9, 99, 75 18, 10, 100, 73 19, 10, 101, 75 20, 11, 102, 73 21, 11, 103, 77 22, 12, 104, 77 23, 13, 105, 74 24, 14, 106, 74 25, 14, 107, 76 26, 14, 108, 75 27, 15, 109, 75 28, 15, 110, 74 29, 15, 111, 76 30, 16, 112, 76 31, 16, 113, 73 32, 16, 114, 75 33, 17, 115, 73 34, 17, 116, 77 35, 18, 117, 77 36, 20, 118, 76 37, 20, 119, 78 38, 21, 120, 76 39, 21, 121, 78 40, 22, 122, 76 41, 22, 123, 78 42, 22, 124, 73 43, 23, 125, 81 44, 23, 126, 78 45, 23, 127, 73 46, 24, 128, 81 47, 25, 129, 80 48, 26, 130, 78 49, 26, 131, 80 50, 27, 132, 78 51, 27, 133, 80 52, 28, 134, 78 53, 28, 135, 80 54, 28, 136, 81 55, 29, 137, 81 56, 29, 138, 78 57, 30, 139, 81 58, 31, 140, 80 59, 32, 141, 80 60, 33, 142, 80 61, 34, 143, 78 62, 34, 144, 80 63, 34, 145, 81 64, 35, 146, 81 65, 36, 147, 81 66, 37, 148, 79 67, 37, 149, 82 68, 38, 150, 82 69, 38, 151, 79 70, 39, 152, 82 71, 39, 153, 75 72, 39, 154, 79 73, 40, 155, 75 74, 41, 156, 77 75, 42, 157, 77 76, 43, 158, 82 77, 43, 159, 79 78, 43, 160, 74 79, 44, 161, 79 80, 44, 162, 82 81, 45, 163, 75 82, 45, 164, 79 83, 46, 165, 75 84, 46, 166, 73 85, 47, 167, 73 86, 47, 168, 77 87, 48, 169, 77 88, 49, 170, 79 89, 49, 171, 74 90, 50, 172, 79 91, 50, 173, 74 92, 50, 174, 76 93, 50, 175, 75 94, 51, 176, 75 95, 51, 177, 79 96, 51, 178, 76 97, 52, 179, 76 98, 52, 180, 73 99, 52, 181, 75 100, 53, 182, 73 101, 53, 183, 77 102, 54, 184, 77 103, 56, 185, 76 104, 56, 186, 78 105, 57, 187, 76 106, 57, 188, 78 107, 58, 189, 76 108, 58, 190, 78 109, 58, 191, 73 110, 59, 192, 73 111, 59, 193, 81 112, 59, 194, 78 113, 60, 195, 81 114, 61, 196, 80 115, 62, 197, 78 116, 62, 198, 80 117, 63, 199, 78 118, 63, 200, 80 119, 64, 201, 78 120, 64, 202, 80 121, 64, 203, 81 122, 65, 204, 81 123, 65, 205, 78 124, 66, 206, 81 125, 67, 207, 80 126, 68, 208, 80 127, 69, 209, 80 128, 70, 210, 81 129, 70, 211, 78 130, 70, 212, 80 131, 71, 213, 81 132, 72, 214, 81 133, 73, 215, 76 134, 74, 216, 75 135, 74, 217, 79 136, 74, 218, 76 137, 75, 219, 76 138, 75, 220, 82 139, 75, 221, 79 140, 76, 222, 78 141, 78, 223, 80 142, 79, 224, 82 \*NSET,NSET=CNODES,GENERATE 1,36 \*NSET,NSET=LNODES,GENERATE 37,72 \*MATERIAL, NAME=Ti6Al4V \*ELASTIC 110000.,.34 \*PLASTIC 880.,0. 950.,0.0035 980.,0.0118 1020.,0.0245 1040.,0.0440 1000.,0.0673 \*DENSITY 4.43E-09 \*BEAM SECTION,ELSET=EAll,MATERIAL=Ti6Al4V,SECTION=CIRC 5.,5. 1.,0.,0. \*BOUNDARY CNODES,1,3 LNODES,1,2 \*STEP,NLGEOM \*STATIC,DIRECT .04,1. \*CLOAD LNODES,3,-10000. \*NODE PRINT,NSET=NAll U \*EL PRINT,ELSET=EAll,TOTALS=YES ELSE,EVOL \*NODE FILE U \*EL FILE ELSE \*END STEP ---
**Author:** ![jbr](https://avatars.discourse-cdn.com/v4/letter/j/ecccb3/32.png) [@jbr](https://calculix.discourse.group/u/jbr)\ **Post date:** [May 6, 2025, 1:59pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/2 "2025-05-06T13:59:36Z")
> [@cellini](#): > > I also find issues when i try to extract the volume from the model. Same type of values. > Does anyone know the possible reason for that? Can you try to expand the model to 3D and check? Many times these 1D elements give erroneous values due to the internal expansion. It may be a bug that needs full reporting. ---
**Author:** ![cellini](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cellini](https://calculix.discourse.group/u/cellini)\ **Post date:** [May 6, 2025, 2:32pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/4 "2025-05-06T14:32:18Z")
Since i know and I can see from the NL results the elements are automatically 3D espanded for probably avoiding shear locking issues. For the volume I can actually avoid the problem by just calculating the distances between the nodes of the beams and then use density and section but for the energy i don’t know. I encountered this problem only because i was trying to set up an automatic convergence process for the results where the criteria were 2: a Mechanical one (using displacements) and ah energetical one (using int energy) ---
**Author:** ![jbr](https://avatars.discourse-cdn.com/v4/letter/j/ecccb3/32.png) [@jbr](https://calculix.discourse.group/u/jbr)\ **Post date:** [May 6, 2025, 3:01pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/5 "2025-05-06T15:01:29Z")
Understood. I will have to check the source code to make sure this a bug. But if you can test an already expanded 3D model, then we know that is the case. ---
**Author:** ![jbr](https://avatars.discourse-cdn.com/v4/letter/j/ecccb3/32.png) [@jbr](https://calculix.discourse.group/u/jbr)\ **Post date:** [May 6, 2025, 4:55pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/6 "2025-05-06T16:55:22Z")
@cellini I tried your input deck and I’m getting regular values. What version of ccx are you running? Which solver? Compiler? I’m running latest 2.22 + Intel One API 2025 with pardiso turned on from MKL. Values are 3.18E+2 on the first element at last converged increment 0.6… solution is actually diverging. ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [May 6, 2025, 7:42pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/7 "2025-05-06T19:42:19Z")
With ccx 2.22 using PaStiX on Windows, I observe non-convergence of this analysis (the values appear normal). With Abaqus, it converges, but I have to change the element type to B32 (Abaqus doesn’t have B32R elements). ---
**Author:** ![cellini](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cellini](https://calculix.discourse.group/u/cellini)\ **Post date:** [May 6, 2025, 8:05pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/8 "2025-05-06T20:05:02Z")
On my calculix command says: CalculiX for Windows version: 2.10 build 002 (64 bit) - so i suppose it should be the 2.10 (?) The fact that the solution is diverging is actually what i expected since this is a reticular structure under strong compression. Run kill indirectly tells me that buckling is happening and thanks to the step and the load set i should be able to find the buckling stress. However if you check the values obtained from the analysis stack in the .dat file you should be able to find for a certain step (let’s say the third one) the internal energy of the structure. What i meant when i wrote the first message was about those values. In those values i found the issue. ---
**Author:** ![Calc\_em](https://avatars.discourse-cdn.com/v4/letter/c/43a26b/32.png) [@Calc\_em](https://calculix.discourse.group/u/Calc_em)\ **Post date:** [May 6, 2025, 8:27pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/9 "2025-05-06T20:27:49Z")
> [@cellini](#): > > On my calculix command says: CalculiX for Windows version: 2.10 build 002 (64 bit) - so i suppose it should be the 2.10 (?) This version is ancient. Considering the amount of bugs that have been fixed since then, you definitely should switch to 2.22. You can get it from here: [https://www.dhondt.de/](https://www.dhondt.de/) ---
**Author:** ![cellini](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cellini](https://calculix.discourse.group/u/cellini)\ **Post date:** [May 6, 2025, 10:34pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/10 "2025-05-06T22:34:33Z")
I will try and i’ll let you know if the issue is still persisting ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 7, 2025, 5:47pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/11 "2025-05-07T17:47:17Z")
I would try with just one member under compresion first to see if your aproach and the element is buckling as expected. Buckling load can be compared with hand calculation. (No plastic card yet). ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 7, 2025, 8:46pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/12 "2025-05-07T20:46:07Z")
I think there is a bug on CIRC element. Frequency analisys shows that constraining Rz (longuitudinal axis) also constrains Rx and RY. One can compare bottom and top response of the beam. ```auto ** Generated by Mecway 28 *NODE 1,0,0,0 2,0,0,1 3,0,0,0.5 4,0,0,0.1666666666667 5,0,0,0.3333333333333 6,0,0,0.6666666666667 7,0,0,0.8333333333333 *ELEMENT,TYPE=B32R 1,6,7,2 2,1,4,5 3,5,3,6 *NSET,NSET=NALL 1 2 *NSET,NSET=CNODES 1 2 *ELSET,ELSET=EALL 1 2 3 *BOUNDARY 1,1,,0 1,2,,0 1,3,,0 1,6,,0 2,1,,0 2,2,,0 *MATERIAL, NAME=Ti6Al4V *ELASTIC 110000.0E6,.0 *DENSITY 44300 *BEAM SECTION,ELSET=EAll,MATERIAL=Ti6Al4V,SECTION=CIRC 5.0E-3,5.0E-3 1.,0.,0. *STEP *FREQUENCY 5 *NODE FILE,GLOBAL=YES U *END STEP ``` @cellini Your buckling load will not be accurate if you only use one element per beam. ---
**Author:** ![jbr](https://avatars.discourse-cdn.com/v4/letter/j/ecccb3/32.png) [@jbr](https://calculix.discourse.group/u/jbr)\ **Post date:** [May 7, 2025, 11:11pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/13 "2025-05-07T23:11:54Z")
> [@Disla](#): > > I think there is a bug on CIRC element. I ran the same input as @cellini provided with 2.22 and pardiso, values seemed to be reasonable. I would say that we need more tests before diagnosing the circ cross-section. ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 8, 2025, 7:34am UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/14 "2025-05-08T07:34:15Z")
Sorry about the terminology. It can be keept as unexpected behaviour until the source of discrepancy is more clear. It is better seen if we only constrain Rz in one node . ```auto *NODE 1,0,0,0 2,0,0,1 3,0,0,0.5 4,0,0,0.1666666666667 5,0,0,0.3333333333333 6,0,0,0.6666666666667 7,0,0,0.8333333333333 *ELEMENT,TYPE=B32R 1,6,7,2 2,1,4,5 3,5,3,6 *NSET,NSET=NALL 1 2 *NSET,NSET=CNODES 1 2 *ELSET,ELSET=EALL 1 2 3 *BOUNDARY 1,6,,0 *MATERIAL, NAME=Ti6Al4V *ELASTIC 110000.0E6,.0 **PLASTIC **880.0E6,0. **950.0E6,0.0035 **980.0E6,0.0118 **1020.0E6,0.0245 **1040.0E6,0.0440 **1000.0E6,0.0673 *DENSITY 4300 *BEAM SECTION,ELSET=EAll,MATERIAL=Ti6Al4V,SECTION=CIRC 5.0E-3,5.0E-3 1.,0.,0. *STEP,PERTURBATION *FREQUENCY 6 *NODE FILE,GLOBAL=YES,OUTPUT=2D U *EL FILE S,NOE,ENER *END STEP ``` There should be 5 rigid body motions and there are only three. ![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/2/2c29e445b23582686bf3c45824ec930e7c058df2.png) It can also be seen in the buckling load. Expected is 33N and result is 81N. | E | 110000 | N/mm2 | | | | | | --- | --- | --- | --- | --- | --- | --- | | L | 1000 | mm | | | | | | Leff | 1000 | mm | | | | | | | | | | | | | | | Circular tube | | | | | | | Radious | A | I | | | | | | 2.5 | 19.63 | 30.680 mm4 | | Euler Buckling Load | 33 | N | ![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/1/121e348b4a244da1accb0112ef845b2dc556efc9.png) ```auto *NODE 1,0,0,0 2,0,0,1 3,0,0,0.5 4,0,0,0.1666666666667 5,0,0,0.3333333333333 6,0,0,0.6666666666667 7,0,0,0.8333333333333 *ELEMENT,TYPE=B32R 1,6,7,2 2,1,4,5 3,5,3,6 *NSET,NSET=NALL 1 2 *NSET,NSET=CNODES 1 2 *ELSET,ELSET=EALL 1 2 3 *BOUNDARY 1,1,,0 1,2,,0 1,3,,0 1,6,,0 2,1,,0 2,2,,0 *MATERIAL, NAME=Ti6Al4V *ELASTIC 110000.0E6,.0 *DENSITY 4300 *BEAM SECTION,ELSET=EAll,MATERIAL=Ti6Al4V,SECTION=CIRC 5.0E-3,5.0E-3 1.,0.,0. *STEP *BUCKLE,SOLVER=PARDISO 6 *CLOAD 2,3,-1 *NODE FILE,GLOBAL=YES,OUTPUT=2D U *END STEP ``` ---
**Author:** ![cellini](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cellini](https://calculix.discourse.group/u/cellini)\ **Post date:** [May 8, 2025, 10:38am UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/15 "2025-05-08T10:38:13Z")
In my project i actually increase the number of elements when convergence for displacements is not reached. I start from a 1 beam - 1 element mesh and then i increase the number of elements for the same beam. After each analysis i take the disp results for a specific step (at about 75% of the total step number) and i confront them with the previous analysis. First analysis with less elements produce a larger number of steps, so quite often the difference is quite important, but it’s good because i want to find the minimum number of elements which does not change the number of steps. After 4-5-6 elements it usually reach the asinthotic number of steps and the convergence kick in well. Last analysis saved is the one with numerical convergence and last step i think indirectly tells when buckling is occuring (since it is a reticular structure). A made a small video to explain better the process at this wetranfer link : [Unique Download Link | WeTransfer](https://we.tl/t-cXH4fkAWp5) If something looks like it can lead to an erroneous results please tell me because i am quite a newbie in calculix About the RZ blocking it actually seems very strange type of behaviour. ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 8, 2025, 3:29pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/16 "2025-05-08T15:29:06Z")
> [@cellini](#): > > If something looks like it can lead to an erroneous results please tell me because i am quite a newbie in calculix Use PIPE instead of CIRC. > [@cellini](#): > > Last analysis saved is the one with numerical convergence and last step i think indirectly tells when buckling is occuring Convergence failure could have other reason than a Buckling failure. A DIRECT timestep itself has some limitations. Plastic collapse could be another failure mode. ---
**Author:** ![cellini](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cellini](https://calculix.discourse.group/u/cellini)\ **Post date:** [May 8, 2025, 8:36pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/17 "2025-05-08T20:36:59Z")
Thank you very much I am trying to perform a simple NL analysis of a beam. Here the source .inp code \*HEADING Model: TESTCASE.inp Date:2025-05-06 \*NODE,NSET=NAll 1, 0.000000, 0.000000, 0.000000 2, 0.000000, 0.000000, 150.000000 3, 0.000000, 0.000000, 300.000000 4, 0.000000, 0.000000, 450.000000 5, 0.000000, 0.000000, 600.000000 6, 0.000000, 0.000000, 750.000000 7, 0.000000, 0.000000, 900.000000 8, 0.000000, 0.000000, 1050.000000 9, 0.000000, 0.000000, 1200.000000 10, 0.000000, 0.000000, 1350.000000 11, 0.000000, 0.000000, 1500.000000 \*ELEMENT,TYPE=B32R,ELSET=EAll 1, 1, 2, 3 2, 3, 4, 5 3, 5, 6, 7 4, 7, 8, 9 5, 9, 10, 11 \*NSET,NSET=CNODES 1 \*NSET,NSET=LNODES 11 \*MATERIAL, NAME=Ti6Al4V \*ELASTIC 110000.,.34 \*PLASTIC 880.,0. 950.,0.0035 980.,0.0118 1020.,0.0245 1040.,0.0440 1000.,0.0673 \*DENSITY 4.43E-09 \*BEAM SECTION,ELSET=EAll,MATERIAL=Ti6Al4V,SECTION=CIRC 5.,5. 1.,0.,0. \*BOUNDARY CNODES,1,6 LNODES,1,2 \*STEP,NLGEOM \*STATIC,DIRECT .04,1. \*CLOAD LNODES,3,-10000. \*NODE PRINT,NSET=NAll U \*EL PRINT,ELSET=EAll,TOTALS=YES ELSE,EVOL \*NODE FILE U \*EL FILE ELSE \*END STEP From what i can see in the results (animation) there is no divergence and it looks strange since buckling is expected. Can it be due to imperfections (that aren’t present) but are essential to trigger the buckling? I ask that because i don’t know at this point if this approach can be correct for proper results ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 8, 2025, 10:06pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/18 "2025-05-08T22:06:28Z")
> [@cellini](#): > > Can it be due to imperfections (that aren’t present) but are essential to trigger the buckling? For a straight beam most probably yes. Inspect the full load path. Buckling might pass unnoticed if you just look at the final picture. Mine doesn’t have imperfections but NLBA can correctly anounce where the buckling load is. ![screenshot.19](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/f/f5faa806d74bb42071b2b4edb9ef043ae9084e63.png) ![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/1/1542c3da319b85df5f90c74185090406d4647088.png) ¿Are you able to compute the expected buckling load on a beam with plasticity? ---
**Author:** ![cellini](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cellini](https://calculix.discourse.group/u/cellini)\ **Post date:** [May 9, 2025, 9:24am UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/19 "2025-05-09T09:24:39Z")
I am trying on this model \*HEADING Model: TESTCASE.inp Date:2025-05-06 \*NODE,NSET=NAll 1, 0.000000, 0.000000, 0.000000 2, 0.000000, 0.000000, 20.000000 3, 0.000000, 0.000000, 40.000000 4, 0.000000, 0.000000, 60.000000 5, 0.000000, 0.000000, 80.000000 6, 0.000000, 0.000000, 100.000000 7, 0.000000, 0.000000, 120.000000 8, 0.000000, 0.000000, 140.000000 9, 0.000000, 0.000000, 160.000000 10, 0.000000, 0.000000, 180.000000 11, 0.000000, 0.000000, 200.000000 12, 0.000000, 0.000000, 220.000000 13, 0.000000, 0.000000, 240.000000 \*ELEMENT,TYPE=B32R,ELSET=EAll 1, 1, 2, 3 2, 3, 4, 5 3, 5, 6, 7 4, 7, 8, 9 5, 9, 10, 11 6, 11, 12, 13 \*NSET,NSET=CNODES 1 \*NSET,NSET=LNODES 13 \*MATERIAL, NAME=Ti6Al4V \*ELASTIC 110000.,.34 \*PLASTIC 880.,0. 950.,0.0035 980.,0.0118 1020.,0.0245 1040.,0.0440 1000.,0.0673 \*DENSITY 4.43E-09 \*BEAM SECTION,ELSET=EAll,MATERIAL=Ti6Al4V,SECTION=CIRC 5.,5. 1.,0.,0. \*BOUNDARY CNODES,1,6 \*STEP,NLGEOM \*STATIC,DIRECT .01,1. \*CLOAD LNODES,3,-20. \*NODE PRINT,NSET=NAll U \*EL PRINT,ELSET=EAll,TOTALS=YES S \*NODE FILE U \*EL FILE S \*END STEP From Euler buck is expected at 18.8 N and i am currently trying 20 N. Except for the first step, i always get disp in xy direction that looks like the ones i attached. The hotspot are however a result of the number of elements used since i tried to change them and i visualized differences. Am i missing something in my .inp file ? ![Immagine 2025-05-09 112517](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/a/a758640b1d04cddf11378bc8e2404599c24a2c5f.jpeg) ---
**Author:** ![Disla](https://yyz2.discourse-cdn.com/free1/user_avatar/calculix.discourse.group/disla/32/3548_2.png) [@Disla](https://calculix.discourse.group/u/Disla)\ **Post date:** [May 9, 2025, 10:58am UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/20 "2025-05-09T10:58:07Z")
Expected Eurler is 144.5N ![imagen](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/3/3f936f7044549d148aad4e1f47cb459024546e17.png) Form that value you can expect some small deviation due to Poisson Ratio and Plasticity. ---
**Author:** ![cellini](https://avatars.discourse-cdn.com/v4/letter/c/b487fb/32.png) [@cellini](https://calculix.discourse.group/u/cellini)\ **Post date:** [May 9, 2025, 12:57pm UTC](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731/21 "2025-05-09T12:57:14Z")
Thank you I found the following results on the middle node. I put 160 N for upper bound and at around 0.9 load factor it experiences displacement peaks. 160 \* 0.9 is around the Euler value so i think this proves the validity of the approach for the circ element. Only thing i wanted to know is why K = 2? for a fixed node i thought it would be just 1 and the effective length equal to the length of the beam. ![Immagine 2025-05-09 145703](https://global.discourse-cdn.com/free1/uploads/calculix/original/2X/7/742d7ae2e29e6d56501a36345fa5adeacd2b9ddc.jpeg) [Next page](https://calculix.discourse.group/t/beam32r-strange-internal-energy-values/2731.md?page=2)