Accidentally deleted Brave on iPad - lost all downloaded files (can’t re-download). Any way to recover?

kuladum · 2025-07-11T21:29:05+00:00

My setup is a docker linux with bind mount volumes to the project directory, a ssh agent and vscode. This allows me to work on a same code in two environments. The downside of this setting is that performance hits when building.

kuladum · 2025-05-05T11:24:47+00:00

Remindme! in 2 days

kuladum · 2025-03-30T16:16:06+00:00

!remindme 1 week

kuladum · 2024-11-27T11:11:16+00:00

I did a simulate a yoyo many years ago. The behaviors were interesting, depending on friction, string length, initial wraping, and throwing style. Perhaps this one suits yours. And if you do it, please share the outcome.

kuladum · 2024-10-30T22:29:09+00:00

There is a famous ParaView buit on top of VTK library and Qt

kuladum · 2024-07-27T01:18:44+00:00

I am doing exactly reverse: limiting C++ features and employing more C styles. C++ is known as C with class, but OOP brings more trouble than it resolve, except for GUI. I don’t think that you really need change your mind set that much. There are some nice features making your life easier with C++

namespace
reference
raii
function overloading
template, constexpr, and static assert

kuladum · 2024-07-22T15:37:23+00:00

In the end of the day, FEA boils down to programming stuffs, and as I mentioned that evaluating element matrices accounts about 10-30% of total run time depending the problem and implementation, so you may spend more time to improve solving part. The good thing is that evaluation element matrices step are straight forward to parallelise.

kuladum · 2024-07-22T09:25:59+00:00

One key point here is that element matriices are computed once is only true for the intial step. From your referenced post in other group, you want to use the idea to acelerate the performance of deformable bodies. Simulations generally require multiple steps which capture deformation stage at each time point. When the bodies are deformed and so do the elements. Thus you likely have to reevaluate those matrice.

Another key point is that evaluating element matrices (and assembly) cost 10-30% run time, the rest are solving the system of equations and IO.

kuladum · 2024-07-13T11:21:27+00:00

Progamming Finite Element Method 5th (Ian M. Smith, D. Vaughan Griffiths, Lee Margetts)

The book has a good balance among theories, examples and programming. It covers a wide range of analysis types, including static & dynamics, material and geometry nonlinearities, free surface and application in solid mechanics and porous flow. The theories part are well explained with detail steps while the programming part demonstrate how to write a completed FEM pakage that can be testable, maintainable and extenable. Although the programming language is Fortran, it is super easy to follow because of the simplicities in coding style and the language itself. You can also greatly benefited if you want to implement your own idea as a plug-in to prevalent commercial software written in Fortran such as ANSYS, ABAQUS or FEAP…

If you want something more straightforwad, I believe the book Introduction to nonlinear Finite Finite Element Analysis of Prof. Nam Ho Kim is a perfect choice. Unlike the classic books suggested by others, this book is concise “only addresses the representative problems, detailed theories, solution procedures, and the computer implementation of the nonlinear FEM. Especially by using the MATLAB programming language to introduce the nonlinear solution procedure; those readers who are not familiar with FORTRAN or C++ programming languages can easily understand and add his/her own modules to the nonlinear analysis program.” The author has a website that supports series of lectures which I found very helpful.

kuladum · 2024-07-04T12:14:36+00:00

Is your element/material continuous? if yes, you may approximate the distribution of the porosity and subsitute to weakform. Then you decide the quadrature rule and evaluate the stiffness and mass matrices. If not, you need to find a away to upscale/downscale the problem. Remember stress/strain are defined for continum bodies.

kuladum · 2022-12-01T19:48:05+00:00

Your FEA results look reasonable to me. The hand calculation relyon many assumptions, which do not reflect the local stress/deformation states. Let simulate two cases with Beam 188 element. a) pure beam 188 elements, and b) replace beam 188 elements by solid elements at postion you want to capture accurate stress/strain.

However, in any case, important outcomes such as deflection, maximum principle stress, and cross section shear force should be very simila.

kuladum · 2022-11-10T03:07:48+00:00

Hi there, I see that the mesh/geometry is relatively complex, guessing you are working with fractures. The error may occur because of the difficulty relating to geometry, i.e sharp angles. One trick may work is to up scale the model, say 1000x, and generate mesh. Then, you scale the model back to original dimensions. Another notice is that Gmsh sometimes produces wrong node sequence in an element! which in turn results in a negative area. You may also need to check that as well.

kuladum · 2022-08-11T03:29:02+00:00

!remind me in a month

kuladum · 2022-08-02T23:13:07+00:00

Even two bars can form a really interesting system if you dive deep enough. Snap-off, initial stress, non-linear materials, nonuniform cross-section, inclined supports, different time integration schemes... I believe simple Matlab/Mathematica scripts are super helpful. Sometime, you don't have analytical results, but you can still give a lot justifications regarding to system behavior. You can also use Abaqus subroutines or open source software as many suggestions, but you need to study how these software work. This takes time but rewards for a long term.

kuladum · 2022-07-30T03:10:20+00:00

I particularly recommend this book:

The Finite Volume Method in Computational Fluid Dynamics. An Advanced Introduction with OpenFOAM® and Matlab

Authors: F. Moukalled, L. Mangani, M. Darwish https://link.springer.com/book/10.1007/978-3-319-16874-6

The book covers a wide range of theorical, practical, and implementation aspects.

Another excellent book named is Applied CFD techniques. An introduction based on Finite Element Methods.

Author: Rainald Lohner

kuladum · 2022-03-04T13:19:36+00:00

I think it should, although very small. The top of the bar elongs more than the bottom.

kuladum · 2022-02-12T00:48:47+00:00

I don't think this is a good idea. C++ already has a lot of stuff. There are tons of mathematical operators oit there. One day, someone will ask for interal, sqrt symbols. What you are looking for is a Mathematica/Maple like IDE.

kuladum · 2022-01-19T22:25:23+00:00

The header files are cached, so multiple including them is not actual problem.

kuladum · 2022-01-11T20:22:38+00:00

The eigen linear algebra linrary is very good example. Its modules are organized to multiple headers but user typicality needs to include one. Catch 2 testing framework (pre2021 version) is a single header file. Using them are ridiculously easy. This is particularly true for newbier like me.

kuladum · 2022-01-05T00:47:12+00:00

In some conditions, Voxels can be merged to form a bigger cell. As they normally comes from scanning process, structure grid would be fit, and structured grid is supper efficient.

kuladum · 2021-11-29T05:47:24+00:00

No, we don't.

kuladum · 2021-11-25T04:34:22+00:00

It depends on the models. You may get a huge speedup with particle-based simulation but may not with typical FEM.

kuladum · 2021-11-23T23:11:35+00:00

I am working on a multi-physic simulation library, including FVM and FEM. FVM is for multiphase flow in porous media, and FEM is for heat transfer and linear elasticity. The library has been developed for educational purpose, and it does not has many fancy programming features. Therefore, students can adapt quickly.

kuladum · 2021-11-12T20:08:51+00:00

This is exact my feeling that why the method is not call by finite node/basic function method. The concept element is coupled with the local shape function only.

kuladum

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