# Blog

### Different Topology optimization solvers used in Ansys

In Ansys commercial FE package, two topology optimization solvers are present based on the SIMP (Solid isotropic material with penalization) method. These solvers include Optimality Criteria (OC) and Sequential Convex Programming (SCP). Sequential Convex Programming: This method is an extension of the Method of Moving Asymptotes (MMA) solver. The MMA solver is a non-linear programming-based […]

### IGA 2: Computational Geometries /Mathematical Preliminaries

This post will deal with the fundamental difference in mathematics behind both FEM and CAD.

### Thin vs Thick Plates

Thin plates are flat structural members with two parallel planes called faces and a cylindrical surface called an edge or boundary. The plate’s thickness ” h” is defined as the distance between the plane faces. The plates can withstand static or dynamic loads that are mostly perpendicular to their faces. Thin plates have several advantages, […]

### Tuple in Python

Tuple is a type of data structure, which is a finite ordered sequence of entities or objects of different data types including numbers, strings, boolean, lists and other tuples. An $n$- tuple is typically an $n$ order tuple containing $n$ elements. Properties of tuple : Ordered – the items are defined in a definite positions […]

### How to use MeshX to convert the mesh file from Gmsh to XDMF file in FEniCS

In FEniCS we have an option of importing the mesh geometry in .xdmf format. This makes our job much more easier and simpler. As it allows us to use different packages (Gmsh, Ansys, Abaqus etc) for complex geometry modeling and meshing. Check this post  to know how to use Nastran file (.bdf) from Ansys to […]

### Variational Calculus: Deriving the strong and weak form

There are many ways in which we can obtain the weak form and the strong form. We focus on the Variational Principles to derive them because FEniCS works on the variational form

### Built-in meshes in FEniCS

In FEniCS, we can either work with the inbuilt meshes or we can also import the mesh file generated in another pre-processing tool as a xdmf format. In order to create inbuilt meshes, firstly, dolfin module is imported as: Matplotlib library is used to display the mesh plots. The different types of inbuilt meshes in […]

### A great advice that I found of the internet

Just keeping it here for future reference References http://www.cs.uni.edu/~wallingf/blog/archives/monthly/2017-08.html https://metarationality.com/rationalism-critiques https://twitter.com/sarahdoingthing/status/877018612447313920?s=20

### Boundary conditions in FEniCS

Boundary conditions (B.C.) are constraints necessary for the solution of a boundary value problem. A boundary value problem is a differential equation (or system of differential equations) to be solved in a domain on whose boundary a set of conditions is known. Boundary value problems are extremely important as they model a vast amount of […]

### A primer on shell structures

Through this post, I attempt to provide a starter pack for shell structures. This includes trying to understand their structural behaviour, a very brief overview of shell-kinematics and the basic methodology for shell analysis through FEM. The theory and implementation follows the widely popular Kirchhoff-Love theory described for thin shells (thickness/length < 20)