## Evaluating Stresses and Forces in Threaded Fasteners with ANSYS Mechanical, Part 2

Fasteners are one of the most common and fundamental engineering components we encounter.

Proper design of fasteners is so fundamental, every Mechanical Engineer takes a University course in which the proper design of these components is covered (or at least a course in which the required textbook does so).

With recent increases in computational power and ease in creating and solving finite element models, engineers are increasingly tempted to simulate their fasteners or fastened joints in order to gain better insights into such concerns as thread stresses

In what follows, PADT’s Alex Grishin digs deeper into how to leverage ANSYS Mechanical to better model fasteners and obtain accurate results. If you did not review Part 1, do so here.

## Evaluating Stresses and Forces in Threaded Fasteners with ANSYS Mechanical

Fasteners are one of the most common and fundamental engineering components we encounter.
Proper design of fasteners is so fundamental, every Mechanical Engineer takes a University course in which the proper design of these components is covered (or at least a course in which the required textbook does so).

With recent increases in computational power and ease in creating and solving finite element models, engineers are increasingly tempted to simulate their fasteners or fastened joints in order to gain better insights into such concerns as thread stresses

In what follows, PADT’s Alex Grishin demonstrates a basic procedure for doing so, assess the cost/benefits of doing so, and to lay the groundwork for some further explorations in Part 2, which can now be found here.

## Can ANSYS Mechanical Handle My Required Modeling Precision?

Sometimes you need to use ANSYS Mechanical to model a big part as a way to determine a very small deflection.  The most common situation where this happens is optics. A lens that is around a meter in diameter may have nanometer distortions from mechanical or thermal loads that impact the optics. A customer asked if ANSYS Mechanical can handle that.  Please find Alex’s interesting and in-depth response in the attached presentation.   There is theory that explains the situation, then an example of how to determine if you can get the information you need, followed by advice on how to view the results.

## Extracting Relative Displacements in ANSYS Mechanical

A recurring theme in ANSYS Technical Support queries involves the separation of rigid-body from material deformations without performing an additional analysis. Many users simply assume this capability should exist as a simple post-processing query(or that in any case, this shouldn’t be a difficult operation). “Rigid-Body” displacements implies a transient dynamic analysis (as such displacements should not occur in static analyses), but as we’ll see, there are contexts within static structural environments where this concept DOES play an important engineering role. In static structural contexts, such rigid-body motion implies motion transmitted across multiple-bodies. There are two important and loosely related contexts we’ll look at; zero strain rotations of the CG and those rotations combined with strain-based displacement.

The following presentation explains the issues including the math behind it, offers solutions including useful APDL marcros, and then gives examples.

The models and macros used are in this zip file: PADT-ANSYS-Extract-Dsp-Files

Find this interesting? This is just a small sample of PADT deep and practical understand of the entire ANSYS Suite of products.  Please consider us for your training, mentoring, and outsourced simulation services needs.

## Estimating Structural Response to Random Vibration in ANSYS Mechanical: Reaction Forces

One of the key outputs from any random vibration analysis is determining the response of the object you are analyzing in terms of reaction forces.  In the presentation below. Alex Grishin shares the theory behind getting accurate forces and then how to do so in ANSYS Mechanical.

## Using External Data in ANSYS Mechanical to Tabular Loads with Multiple Variables, Part 2

ANSYS Mechanical is great at applying tabular loads that vary with an independent variable. Say time or Z.  What if you want a tabular load that varies in multiple directions and time. In part one of this series, I covered who you can use the External Data tool to do just that. In this second part, I show how you can alternatively use APDL commands added to your ANSYS Mechanical model to define the tabular loading.

## Secant or Instantaneous CTE? Understanding Thermal Expansion Modeling ANSYS Mechanical

One of the more common questions we get on thermal expansion simulations in tech support for ANSYS Mechanical and ANSYS Mechanical APDL revolve around how the Coefficient of Thermal Expansion, or CTE. This comes in to play if the CTE of the material you are modeling is set up to change with the temperature of that material.

This detailed presentation goes in to explaining what the differences are between the Secant and Instantaneous methods, how to convert between them, and dealing with extrapolating coeficients beyond temperatures for which you have data.