Linear Elasticity Solver Archives - ESRD

StressCheck Tutorial: New Assembly Meshing/Auto Contact Features in StressCheck v12.0

brent — Wed, 11 Sep 2024 20:11:43 +0000

A new and powerful assembly automeshing/automatic contact detection feature is now available with the release of StressCheck v12.0. Before automeshing an assembly of close-contacting solid bodies, users may enable the "Assembly Meshing" option to enforce element face matching between neighboring surfaces (to within a user-specified tolerance). Once the solid bodies have been automeshed, StressCheck will automatically create contact zones between matched neighboring element faces and assign contact pairs via the new Auto Contact constraint method to the current constraint ID (if existing, otherwise StressCheck will use "AUTO_CONT" as the constraint ID). Individual contact pairs generated via the Auto Contact method may specified as Contact (the default, traditional multi-body contact), Fused (if element face matching was 100% successful, matched element faces are bonded) or Free (matched element faces are free). Note that if individual contact pairs are specified as Contact, and a parameter is not used for the Contact Constant, the Contact Constant value is computed from the assigned material property data and will be updated if one or more of the material properties are modified. This tutorial revisits a previous 3D multi-body contact example and utilizes assembly automeshing/automatic contact detection to significantly reduce the amount of setup time for multi-body contact analysis. The tutorial also demonstrates how refining the automesh (or updating a parameter value which triggers a re-mesh) will result in the re-generation of the contact zones/contact pairs.

Experimental Validation of DTA Modeling of Bonded Wing Skin Repairs

brent — Thu, 07 Dec 2023 16:41:37 +0000

Abstract: This presentation is a follow-up to ESRD’s 2022 ASIP presentation titled “DTA of Bonded Repairs on the Wing Skin of the C-130 Using Finite Elements.” That presentation explored a robust method for finite element analysis of bonded skin repairs from the perspective of both static strength and fatigue crack growth. The proposed analysis methodology was presented in a comparative sense, examining a number of criteria in the skin in an undamaged state, a damaged state and a repaired state, in order to allow the analyst to make an assessment of repair effectiveness without detailed knowledge of either the exact boundary conditions of the problem, or of the intricacies of the model itself. One of the criteria for a patch to be deemed effective is that the fatigue life of the skin be at or above that of the pristine configuration. Given the sparse nature of research on the topic of crack growth under bonded repair patches, ESRD partnered with AP/ES to conduct an experimental program to investigate in detail how a small initial flaw propagates in the aluminum skin under a titanium repair up through failure. Experiments were performed alongside blind predictions of life and crack morphology using ESRD’s research tool, CPAT. Additionally, statistical analysis was performed to assess confidence in the predictions. Given the aleatory uncertainty associated with the available crack growth data for the specimen material, it was important that predictions of fatigue life be accompanied by a confidence level when comparing them with experimental outcomes. Because most of the crack propagation occurred under the repair, a marker band spectrum was used during the test and the crack-cycle data was constructed from fractographic examination. The experimental program covered three specimen configurations: (1) Undamaged skin with a surface crack or a corner crack at a hole; (2) Skin with a grindout (to remove hypothetical corrosion damage) and either a surface crack at the bottom of the grindout or a corner crack at a hole located at the center of the grindout; (3) Same as configuration (2) but including a bonded titanium repair. Experimental and predicted results will be presented. Originally presented as a technical paper at the 2023 ASIP conference in Denver, CO.

ASIP 2023 Training – Enhancements in StressCheck v12.0 for DaDT Analysis of 3D Fastened Connections

brent — Thu, 07 Dec 2023 15:55:57 +0000

Abstract: this 2-hour training course, originally presented at the ASIP 2023 conference in Denver, CO, explored the following topics:

StressCheck’s FEA technology implementation for the modeling, meshing and analysis of arbitrarily shaped 3D crack geometries, with and without the local effects of multi-body contact.
Strategies for automatic meshing of 3D cracks with high-aspect ratio, 3D-solid pentahedral and hexahedral elements to support high-quality SIF extractions at any location on the crack front.
New StressCheck 12.0 method to support multi-body contact assembly meshing, auto-detection of contact regions, and automatic assignment of contact pairs for 3D solid bodies.

StressCheck Demo: 2D Splice Joint Case Study

brent — Fri, 02 Jun 2023 16:15:21 +0000

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StressCheck Demo: Computing 2D and 3D Stress Concentrations for an Infinite Plate with Hole in Tension

brent — Wed, 24 May 2023 15:23:34 +0000

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StressCheck Tutorial: Importation and Assignment of Point Displacements & Rotations via the Fit-Auto Method

brent — Fri, 17 Mar 2023 15:58:28 +0000

Abstract: demonstration of 1) how to format an ASCII file containing nine (9) columns of tabular point displacement/rotation data (X, Y, Z, Ux, Uy, Uz, Rx, Ry, Rz) for importation into StressCheck, and 2) how to assign the imported point constraint data to the surfaces of an imported solid (via the Fit-Auto constraint method) for a global-local analysis. For more details, consult Point Displacements/Rotations Implementation.

StressCheck Tutorial: Improving Multi-Body Contact Efficiency and Quality via Hexa/Penta Boundary Layer Refinement

brent — Fri, 17 Mar 2023 15:41:01 +0000

Abstract: demonstration of how refining surfaces in contact with at least one hexa-dominant mesh layer (via the mixed Boundary Layer automesh method) improves the outcomes of multi-body contact solutions. The mixed Boundary Layer automesh method is available as of StressCheck v11.1. For more details, refer to MeshSim Automesh Generation Methods.

Webinar: Benefits of Mixed Meshing for Multi-Body Contact Applications

brent — Mon, 13 Mar 2023 20:42:18 +0000

[vc_row][vc_column width="1/2"][vc_message message_box_color="peacoc" icon_fontawesome="fa fa-lightbulb-o"]March 13, 2023 @ 1:00 pm EST[/vc_message][vc_column_text]Strategies for incorporating advanced mixed (hexa/penta) automeshing techniques for improved quality and efficiency of 3D multi-body contact applications will be explored.[/vc_column_text][vc_cta h2="" add_button="right" btn_title="WATCH NOW" btn_color="danger" btn_link="url:%23recording|||"]This webinar is now available to watch on-demand.[/vc_cta][/vc_column][vc_column width="1/2"] [caption id="attachment_27442" align="alignnone" width="1166"] 3D Splice Plate problem definition (top right), mixed mesh taking advantage of symmetry (top left) and plate von Mises stresses (bottom).[/caption] [/vc_column][/vc_row][vc_row][vc_column][vc_column_text]

WEBINAR SUMMARY

[/vc_column_text][vc_custom_heading text="In this 3-part, pre-recorded 40-minute webinar we will present how the automeshing enhancements now available in StressCheck v11.1 significantly aid in the rapid generation of penta- and hexa-dominant meshes for use in 3D multi-body contact applications. To realize these concepts in a practical setting, a 3D splice joint assembly will be constructed, analyzed and post-processed, with detailed commentary on each step in the workflow process." font_container="tag:p|text_align:left" use_theme_fonts="yes"][/vc_column][/vc_row][vc_row][vc_column][vc_column_text]

WEBINAR HIGHLIGHTS

[/vc_column_text][vc_column_text]Part 1: Model Definition & Parametric Geometry Construction

Problem definition, scope and use of symmetry to reduce model size
Importation of a parameter file (.par)
Construction of 3D parametric solid bodies (boxes, cylinders, cones, etc.)
Boolean union/subtraction operations between 3D solid bodies to define 3D splice joint parts
Copy operations to duplicate child fastener bodies from a single parent fastener body
Body-to-body imprints between all parts for optimization of contacting surfaces

Part 2: Part Definition, Contact Zone Setup, Mixed Mesh Generation, Material Properties & Boundary Conditions

Creation of Parts for efficient bookkeeping and visualization
Generation of the solid mixed meshes for each Part via Global, Boundary Layer and Thin Section automesh methods
Creation of contact zones for Part regions expected to be in contact
Definition and assignment of material properties to each Part
Assignment of boundary conditions (loads and constraints) to each Part
Assignment of contact pairs to allow gap and pressure computations between Part contact zones

Part 3: Solution Setup, Execution and Post-Processing

Linear multi-body contact solution setup and initiating the solver
Evaluation of max contact pressure error, solve time and degrees of freedom solved (DOF)
Plotting the deformation of the 3D splice joint assembly
Plotting of von Mises stresses for each Part in the 3D splice joint assembly
Unaveraged vs. averaged von Mises stresses for each plate Part
Computing the stress resultants to ensure quality load transfer between Parts
Summary and wrap-up

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What’s New and Improved in StressCheck Professional Webinar Slides (2023)

brent — Wed, 15 Feb 2023 15:54:08 +0000

This 2-hour webinar provided demonstrations of the "latest and greatest" enhancements in StressCheck v11.1, and a look toward future development activities happening in the next StressCheck release in Summer 2023. Some highlights of the webinar included:

Overview of recent features and enhancements already implemented in StressCheck Professional
Demonstration of key features and enhancements available in StressCheck v11.1
Overview of current development activities and future plans for StressCheck Professional
Demonstration of key features and enhancements expected with the next release of StressCheck
Open discussion and Q&A

To view the webinar recording, click here.

StressCheck Demo: Thermo-Mechanical Analysis with Temperature-Dependent Material Properties

brent — Wed, 18 Jan 2023 19:10:09 +0000

Abstract: A thermo-mechanical (Heat Transfer -> Elasticity) analysis is performed for a Handbook model of two Inconel 718 connected pipes connected by a thin fin (\Handbook\Tutorial\ConnectedPipes.scw). The parametric Handbook model contains formula-based, temperature-dependent coefficients of thermal conductivity (when the theory is Heat Transfer) as well as formula-based, temperature-dependent linear isotropic material properties (when the theory is Elasticity). The goals of the thermo-mechanical analysis are to:

Compute the linear (coefficient of thermal conductivity for a reference temperature T=200 °F) and material nonlinear (coefficient of thermal conductivity is allowed to be temperature-dependent) temperature distributions via steady-state conduction heat transfer
Apply the temperature distribution computed from the material nonlinear solution as a thermal load for all elements using a reference temperature of 0 °F
Solve a linear elastic solution using the thermal load, symmetry/rigid body constraints, and temperature-dependent linear isotropic properties
Extract the local stresses at the intersection of the fin and the pipes.

For the steady-state conduction heat transfer analysis, the following boundary conditions are assigned:

Cooling of the external pipe surfaces is by convection via parameters "Hc" (convective film coefficient) and "Tc"(convective temperature).
The left pipe inside temperature is given by parameter "To", and the right pipe inside temperature is given by parameter "Tp".

For the linear elastic analysis, the following boundary conditions are assigned:

Thermal loading of the connecting pipes + fin is defined by importing the temperatures from the material nonlinear steady state conduction heat transfer solution.
Double-symmetry conditions are used to model 1/4 of the connecting pipes + fin.
A nodal constraint in the global X direction restricts rigid body translation.