In steel structure design, the calculation of component stability is more crucial than the calculation of component strength. Linear buckling analysis tends to be conservative, thus solely conducting a linear eigenvalue analysis is insufficient now. To achieve results closer to real-world engineering scenarios, it is essential to perform nonlinear buckling analysis. In Ansys, the STATIC analysis combined with the application of the arc-length method enables a comprehensive buckling analysis of the component throughout the buckling process.

Beam elements are recognized for their simplicity and efficiency, making them widely used in finite element analysis, especially within structural engineering. Utilizing beam elements avoids the requirement to model all components as solid elements, thereby reducing computational effort. Beam elements provide a straightforward structural format with relatively high accuracy. In Ansys, beam elements are generally classified into linear and quadratic elements, with different computational theories. The integration points for the classic quadratic element, BEAM189, are shown in the following image:

This article analyzes a tapered collet in operation. Tapered collets are commonly used mechanical devices that employ sleeve compression to clamp workpieces. This involves friction between the sleeve and the clamp, as well as between the clamp and the workpiece. The frictional force can be determined when the workpiece is pulled. This provides insight into the load-bearing capacity of the entire mechanical assembly. A cross-sectional view of the model is illustrated below,

In practical analyses, nonlinear contact between structures or components is frequently encountered. Contact problems, a type of nonlinear behavior, often require significant computational resources. To conduct a analysis, it is essential to establish an effective model. Setting up contact analyses in Ansys typically involves two main issues:

In structural engineering, Ansys is predominantly used for elastic analysis or elastic-plastic analysis of steel structures. However, when dealing with reinforced concrete frames, Ansys sometimes has issues, primarily because the concrete material in Ansys is intended to be used with the SOLID65 element. While most building structures consist of frames, simulating all elements/frames of a structure with SOLID65 requires substantial computational cost and also poses a convergence challenge.

During structural analysis, it is common to use multiple types of elements together. This leads to issues related to the connection between elements. General elements like beams, shells, and solid elements usually connect via shared nodes. However, due to the differences in degrees of freedom (DOF) between elements, such connections might not yield the desired results and can even lead to issues that prevent model convergence. Thus, it is necessary to create “compatibility conditions” between different elements.

Previously, when I analyzed a steel structure with residual stress, it is difficult to apply residual stresses correctly and could not identify the problem until I came across a case study on applying residual stresses. In Ansys, initial stresses can be considered as a load but are only applicable in static and transient analyses. Constant initial stresses can be applied using the ISTRESS command.

The Drucker-Prager (DP) material model in Ansys is a non-metallic material model that can consider volume expansion caused by yielding. Thus, it is suitable for simulating granular materials with friction, concrete, rocks, etc. Unlike metallic materials, the DP material model can use both associated and non-associated flow rules. However, the DP material does not have a hardening rule and its yield surface expands with an increase in hydrostatic pressure, exhibiting ideally elastic-plastic behavior. The equivalent stress for the DP model is defined by the following equation,

When conducting structural analysis in Ansys, modal analysis often does not consider the external loads applied to the model. Even when prestress is applied, Ansys usually does not consider the effect of prestress, which does not match the actual situation. Therefore, it is necessary to enable the prestress effects in the analysis to obtain more accurate results.

I have worked on several concrete analysis cases and I found that it is possible to establish a refined model of concrete, including models for concrete aggregates and mortar. This is quite interesting. So, I searched online and discovered many papers and studies on this topic. I also realized that the random generation of concrete aggregates indeed involves certain techniques. After reviewing some papers, I found that the random generation of aggregates mainly relies on coding skills. To achieve the required aggregate gradation, various “advanced methods” can be added to the generation algorithm, such as using the Monte Carlo method to generate graded concrete aggregate models, as well as generating irregular aggregates.