# Incorrect displacement results with shell edge load on shell composite model **URL:** \ **Category:** General Questions\ **Created:** [March 21, 2026, 9:19am UTC](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359 "2026-03-21T09:19:54Z")\ **Posts on this page:** 7\ **Page:** 2
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [March 22, 2026, 3:15pm UTC](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359/21 "2026-03-22T15:15:39Z")
> [@FEAnalyst](#): > > I think I have better agreement when it comes to displacement (something above 0.3), but I’ll need to check. ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/5/5d5cd89f63420655c313fa730a5247789bd2f0e9.jpeg) ---
**Author:** ![yvan](https://avatars.discourse-cdn.com/v4/letter/y/3ab097/32.png) [@yvan](https://prepomax.discourse.group/u/yvan)\ **Post date:** [March 22, 2026, 6:29pm UTC](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359/22 "2026-03-22T18:29:24Z")
Thanks again @FEAnalyst I agree another test with reference results would help, but I really thought this tensile coupon (dog ears shape) was simple enough to start with… I will check with a simple constant-section rectangular plate, and compare with analytical solution. But it would be good to fully understand why such large differences between Calculix and Abaqus, with very similar dimensions / mesh / load / BC. ---
**Author:** ![synt](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/synt/32/4658_2.png) [@synt](https://prepomax.discourse.group/u/synt)\ **Post date:** [March 23, 2026, 1:42am UTC](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359/23 "2026-03-23T01:42:46Z")
when no reference solution available, usually solid element model is used since it’s the most accurate ones. I’m only look based on several screenshot and results, Abaqus shell composite results are underestimate and CalculiX composite shell is overestimated, both are less accurate. However, refine the mesh in CalculiX composite shell result is closed to solid models. Some reason commonly from stress in thickness direction and shear transfer distribution in each layer. ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [March 23, 2026, 7:31am UTC](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359/24 "2026-03-23T07:31:48Z")
That’s why I propose another benchmark with a reference solution. Here, we don’t know the correct value and both Abaqus and CalculiX can be wrong due to insufficient discretization (likely in-plane since even if we add more integration points in the thickness direction, they can still be too far from the fillet’s surface). I can try different element types (including solids and continuum shells) and refined mesh in that area in Abaqus. I will also have a look at averaging. We should use full integration second-order solids for that (while composites in CalculiX need S8R), but with the current mesh density, C3D20 elements in CalculiX don’t help. ---
**Author:** ![yvan](https://avatars.discourse-cdn.com/v4/letter/y/3ab097/32.png) [@yvan](https://prepomax.discourse.group/u/yvan)\ **Post date:** [March 23, 2026, 9:46pm UTC](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359/25 "2026-03-23T21:46:22Z")
@FEAnalyst I followed your advice, and prepare a new test case to compare between ABQ and Calculix, using NAFEMS benchmarks (three-point bending test). Problem is that my Abaqus model does not give the expected reference results. I should have something wrong in my model but do not see what. I also followed this guide: > **[FEA-Portfolio/cfrp-three-point-bend at main · dmytrokuksenko/FEA-Portfolio](https://github.com/dmytrokuksenko/FEA-Portfolio/tree/main/cfrp-three-point-bend)** > > Contribute to dmytrokuksenko/FEA-Portfolio development by creating an account on GitHub. Could you please help me ? Here are the ‘cae’ and ‘inp’ files zip). [NAFEMS\_three-point-bending\_ABAQUS.zip](https://prepomax.discourse.group/uploads/short-url/t7OXq9vEBjRFaVKyMnQTe9NO2OD.zip) (86.6 KB) Here is the NAFEMS description : (we should expect about 1mm of U3 deflection at max) ![image](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/6/67179d6925932d07ea06eb6c4b616a4706d7f310.png) ---
**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\ **Post date:** [March 23, 2026, 10:03pm UTC](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359/26 "2026-03-23T22:03:38Z")
> [@yvan](#): > > Problem is that my Abaqus model does not give the expected reference results. Try the input file provided in the Abaqus documentation for this benchmark: [http://130.149.89.49:2080/v2016/books/bmk/default.htm?startat=ch04s09anf81.html](http://130.149.89.49:2080/v2016/books/bmk/default.htm?startat=ch04s09anf81.html) You could import it in Abaqus/CAE and then recreate it there (even including the geometry) if you want. Or convert the input deck for use in CalculiX if needed. ---
**Author:** ![yvan](https://avatars.discourse-cdn.com/v4/letter/y/3ab097/32.png) [@yvan](https://prepomax.discourse.group/u/yvan)\ **Post date:** [March 23, 2026, 10:39pm UTC](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359/27 "2026-03-23T22:39:49Z")
Many thanks. I was then able to see my error (I did not applied Simpson’s distribution rule for load force values on nodes). [Previous page](https://prepomax.discourse.group/t/incorrect-displacement-results-with-shell-edge-load-on-shell-composite-model/3359.md?page=1)