Plate/shell structures – BuildSoft Support https://support.buildsoft.eu BuildSoft Support Mon, 23 Jun 2025 21:57:28 +0000 en-US hourly 1 https://wordpress.org/?v=6.2.14 DLS 02: Lozenge – shaped thin plate with one edge fixed – eigenfrequencies https://support.buildsoft.eu/knowledge-base/lozenge-shaped-thin-plate-with-one-edge-fixed-eigenfrequencies/ Fri, 17 Nov 2023 14:19:45 +0000 https://support.buildsoft.eu/?post_type=ht_kb&p=10959 Description

Material Modulus of elasticity E=210 000 N/mm^2
Density \rho=7800 kg/m^3
Poisson’s ratio \nu= 0.3
Geometry Cross-section Thickness e = 10mm
Boundary conditions Along line AB Fixed support
Consider a case for each angle α = 15°, 30°, 45°
Mesh Maximum element size 0.05m
Minimum element size 0.00m
How do I model a skew plate?

Results

For α = 15°

Eigen mode Shape Independent reference Diamonds Difference
1 8.999Hz 8.950Hz -0.54%
2 22.171Hz 21.751Hz -1.9%

For α = 30°

Eigen mode Shape Independent reference Diamonds Difference
1 9.899Hz 9.823Hz -0.76%
2 25.465Hz 23.534Hz -7.58%

For α = 45°

Eigen mode Shape Independent reference Diamonds Difference
1 11.121Hz 11.292Hz 1.54%
2 23.390Hz 28.134Hz 6.61%

References

  • Mécaniciens, S. F. D. (1990). Guide de validation des progiciels de calcul des structures: SDLS 02: plaque Losange mince encastrée sur un bord
  • Tested in Diamonds 2026.
]]> DLS 05: Compressor blade: thin shell – eigenfrequencies https://support.buildsoft.eu/knowledge-base/dls-05-compressor-blade-thin-shell-eigenfrequencies/ Thu, 16 Nov 2023 13:51:07 +0000 https://support.buildsoft.eu/?post_type=ht_kb&p=10944 Description

Material Modulus of elasticity E=206 850 N/mm^2
Density \rho=7857.2kg/m^3
Poisson’s ratio \nu= 0.3
Geometry Cross-section Thickness e = 3.05mm
Boundary conditions Along the inner circle Fixed support
Mesh Maximum element size 0.01m
Minimum element size 0.00m

Results

Eigen mode Shape Independent reference Diamonds Difference
1 85.6Hz 87.1Hz -1.72%
2 134.5Hz 140.1Hz -4.00%
3 259.0Hz 248.2Hz 4.35%
4 351.0Hz 348.2Hz 0.8%
5 395.0Hz 391.1Hz 1.00%
6 531.0Hz 531.1Hz -0.02%

References

  • Mécaniciens, S. F. D. (1990). Guide de validation des progiciels de calcul des structures: SDLS 05: aube de compresseur: coque mince encastrée-libre
  • Tested in Diamonds 2026.
]]> DLS 04: Circular plate fixed at inner edge – eigenfrequencies https://support.buildsoft.eu/knowledge-base/dls-04/ Thu, 16 Nov 2023 08:17:12 +0000 https://support.buildsoft.eu/?post_type=ht_kb&p=10898 Description

Material Modulus of elasticity E=200 000 N/mm^2
Density \rho=7800 kg/m^3
Poisson’s ratio \nu= 0.3
Geometry Cross-section Thickness e = 10mm
Boundary conditions Along the inner circle Fixed support
Mesh Maximum element size 0.20m
Minimum element size 0.00m

Results

Handcalculation

    \[f_i=\frac{1}{2\cdot \pi \cdot R^2}\cdot \lambda_{ij} \cdot \sqrt{\frac{E \cdot e^2}{12\cdot (1-\nu^2) }}\]

    \[ f_i=\frac{1}{2\cdot \pi \cdot R^2}\cdot \begin{bmatrix}13.0 \\ 13.3 \\ 14.7 \\ 18.5 \\ 85.1 \\ 86.7 \\ 91.7 \\ 100.0 \end{bmatrix}\cdot \frac{h}{R^2}\cdot \lambda_{ij} \cdot \sqrt{\frac{E \cdot e^2}{12\cdot (1-\nu^2) }}= \begin{bmatrix}7.93 \\ 8.11 \\ 8.96 \\ 11.28 \\ 51.89 \\ 52.86 \\ 55.91 \\ 60.97 \end{bmatrix} Hz\]

Eigen mode Shape Independent reference Diamonds Difference
1 7.93Hz 8.00Hz (M1) 0.93%
2 8.11Hz 8.15Hz (M2) 0.51%
3 8.96Hz 9.01Hz (M4) 0.53%
4 11.28Hz 11.38Hz (M6) 0.89%
5 51.89Hz 53.29Hz (M19) 2.71%
6 52.86Hz 53.42Hz (M20) 1.06%
7 55.91Hz 54.23Hz (M22) -3.00%
8 60.97Hz 57.57Hz (M24) -5.58%

The difference between the first 4 and last 4 eigen frequencies are the type of shape mode. There are a few shape modes (accompanied by an eigen frequency) between 11.28 en 51.89Hz which are not listed in the table above.

References

  • Mécaniciens, S. F. D. (1990). Guide de validation des progiciels de calcul des structures: SDLS 04: plaque mince annulaire encastrée sur un moyeu
    The dimensions of the Afnor example were too small for Diamonds. So the radius R and young’s modulus E have been adjusted, and the results are recalculated accordingly.
  • Tested in Diamonds 2026.
]]> DLS 03: Rectangular thin plate – simply supported – eigenfrequencies https://support.buildsoft.eu/knowledge-base/dls-03/ Sat, 11 Nov 2023 10:54:07 +0000 https://support.buildsoft.eu/?post_type=ht_kb&p=10789 Description

Material Modulus of elasticity E=210 000 N/mm^2
Density \rho=7800 kg/m^3
Poisson’s ratio \nu= 0.3
Geometry Cross-section Thickness e = 10mm
Boundary conditions Along line AB Fixed support
Mesh Maximum element size 0.05m
Minimum element size 0.00m

Results

Eigen mode Shape Independent reference Diamonds Difference
1 35.63Hz 35.6Hz -2.81%
2 68.51Hz 68.61Hz 0.15%
3 109.62Hz 110.11Hz 0.45%
41 123.32Hz 123.97Hz 0.53%
51 142.51Hz 143.42Hz 0.64%
61 197.32Hz 199.27Hz 0.99%
1 The higher the modes become, the more complex the modes shapes are and the more mesh nodes are required to get aquirate results. Therefor a relative small mesh size was chosen for this example.

References

  • Mécaniciens, S. F. D. (1990). Guide de validation des progiciels de calcul des structures: SDLS 03: plaque rectangulaire mince simplement appuyée sur les bords
  • Tested in Diamonds 2026.
]]> DLS 01: Cantilever square thin plate – eigenfrequencies https://support.buildsoft.eu/knowledge-base/cantilever-square-thin-plate-eigenfrequencies/ Thu, 09 Nov 2023 14:51:14 +0000 https://support.buildsoft.eu/?post_type=ht_kb&p=10654 Description

Material Modulus of elasticity E=210 000 N/mm^2
Density \rho=7800 kg/m^3
Poisson’s ratio \nu= 0.3
Geometry Cross-section Thickness e = 10mm
Boundary conditions Along line AB Fixed support
Mesh Maximum element size 0.10m
Minimum element size 0.00m

Results

Eigen mode Shape Independent reference Diamonds Difference
1 8,7266Hz 8,6657Hz 0,70%
2 21,3042Hz 21,3191Hz 0,07%
3 53,5542Hz 53,6234Hz 0,13%
4 68,2984Hz 68,7343Hz -0,57%
5 77,7448Hz 78,3880Hz 0,06%
6 136,0471Hz 138,7942Hz -2,22%1
1 The results improve with a smaller mesh size.

References

  • Mécaniciens, S. F. D. (1990). Guide de validation des progiciels de calcul des structures: SDLS 01: plaque carrée mince libre ou encastrée sur un bord
  • Tested in Diamonds 2026.
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