AFGROW User Workshop 2022

Davis Conference Center Davis Conference Center
1651 North 700 West
Layton, Utah 84041

The next AFGROW Workshop will be held at Davis Conference Center in Layton, UT on September 13-14, 2022.

Are you, or someone you know, interested in learning about the latest developments happening right now in Fracture Mechanics? Would you like the chance to meet a wide range of experts from across the industry? Do you want to know more about the uses and capabilities of Crack Growth Analysis tools? All of these opportunities and more are available to you at the AFGROW Users Workshop.

The purpose of the Workshop is to provide a forum for AFGROW Users to come together to exchange information and best-practices, network with peers from the industry, and get a chance to talk with the AFGROW developers and community.

Group discussions will also provide direction for new capabilities and improvements, best practice methods, and tips and tricks from the experts. The AFGROW team will also provide information on our latest development efforts for the upcoming year.

Who should attend: Engineers, researchers, technologists, managers who are users of AFGROW, and/or anyone that has an interest in Crack Growth Analysis tools.

The Davis Conference Center is close to the Hill AFB South Gate, and is conveniently close to several hotels in Clearfield and Layton. Continental breakfast and afternoon refreshments will be provided.

You can register for the User Workshop online or alternatively you can download the registration form and fax or email it to us.

Register Online for Workshop

Workshop Agenda (in progress)

8:00 AM
9:00 AM
10:00 AM
11:00 AM
12:00 PM
1:00 PM
2:00 PM
3:00 PM
4:00 PM
5:00 PM
AFGROW release 5.4 8:30AM- 9:30AM

 James Harter, Alex Litvinov, James Lambert, Mathew Gross, Yevhen Saltovets (LexTech, Inc.)

AFGROW Future Development Discussion 9:30AM- 10:00AM

 James Harter, Alex Litvinov (LexTech, Inc)

Continuing Damage Testing and Modeling 10:30AM- 11:00AM

 Matt Andrus (USAF, T-38 Structural Integrity & Analysis Group)

Multisite Damage Solution 11:00AM- 11:30AM

 James Harter (LexTech, inc.)

Determination of bearing stress equivalent width 11:30AM- 12:00PM

 Luciano Smith*, Ghadir Haikal*, and Kaylon Anderson** ( *SwRI, ** USAF, A-10 ASIP Analysis Group )

Fatigue-Crack-Growth Testing on Two Aluminum Alloys under Single-Spike Overloads and Constraint-Loss Behavior 1:00PM- 2:00PM

 J. C. Newman, Jr.*, K. F. Walker** (*Fatigue & Fracture Associates, LLC, **QinetiQ)

Spectrum manager overview 1:00PM- 1:30PM

 Matthew Gross (LexTech, Inc.)

BAMpF Consortium Group Meeting 3:00PM- 4:30PM

 Joshua Hodges (Hill Engineering)

Reconstruction of B-52 DTA Using AFGROW 3:30PM- 4:00PM

 Casey Scott (Modern Technology Solutions, Inc.)

Solution for Combinations of Corner and Straight Through Cracks At Hole 4:00PM- 4:30PM

 James Lambert, Alex Litvinov, Yevhen Saltovets (LexTech, Inc.)

If you would like to make a 20 or 40 minute presentation, please submit an abstract to . If you have a topic that requires more time, let us know and we will do our best to accommodate you.

AFGROW release 5.4
James Harter, Alex Litvinov, James Lambert, Mathew Gross, Yevhen Saltovets - LexTech, Inc.

AFGROW, Release 5.4 includes several new features and capabilities. The most important new capabilities/features include: a new, advanced solution for combinations of a corner crack and through crack on either side of a hole; new MSD solutions; new weight function solutions for single corner crack and a single corner crack at hole with the stress distribution in C direction and double/single through crack(s) at hole.

AFGROW Future Development Discussion
James Harter, Alex Litvinov - LexTech, Inc

Validation of 3D FEM based solutions using fatigue crack growth measurements in piping specimens
Adrian Loghin - Simmetrix Inc.

Accurate Finite Width Correction Functions for a Crack at a Straight Shank Hole
Börje Andersson - BARE, AB Sweden

Available finite width correction functions Fw that have been used in aircraft community for decades were developed based on a very limited number of FE-solutions, often of unknown accuracy and by mixing 2D/3D solutions with partly unverified assumptions used for inter-/extrapolation. The accuracy of the Fw-functions obtained in this way was in most cases estimated from comparisons with the FE-solutions that was used to derive the Fw-functions. Hence, the accuracy of the existing Fw-functions in the entire parameter space (R/t, W/R, a/t, a/c) has remained unknown until now.

In the present lecture we derive very accurate finite width correction functions Fw (R/t, W/R, a/t, a/c) for a single quarter-elliptical crack (dimensions (a, c)) at a straight shank hole (radius R) in a plate (thickness t, width 2·W and height 10·W) subject to tension, bending and pin loading.

Fatigue-Crack-Growth Testing on Two Aluminum Alloys under Single-Spike Overloads and Constraint-Loss Behavior
J. C. Newman, Jr.*, K. F. Walker** - *Fatigue & Fracture Associates, LLC, **QinetiQ

In 1966, Schijve found that the transition from flat-to-slant (plane-strain to plane-stress) crack-growth behavior occurred at a "constant" crack-growth rate, independent of the stress ratio (R). Others had proposed that ΔK or Kmax controlled the transitional behavior. Newman (1966) had provided additional test data from the NASA Langley Research Center to support Schijve’s conclusion that crack-growth rate was the controlling parameter. In 1968, Elber discovered the crack-closure phenomenon, whereby the crack surfaces are partially-closed under tensile loading. Cracks only grow when the crack tip is fully open. Elber proposed to modify the Paris expression as

dc/dN = C (ΔKeff)n (1)

Since the crack-closure concept correlated fatigue-crack-growth-rate data on a unique ΔKeff-rate curve, independent of R, the flat-to-slant crack transition is controlled by ΔKeff. In 1992, Newman developed an expression for the flat-to-slant (constraint-loss) regime in terms of ΔKeff, as

(ΔKeff)T = 0.5 σo sqrt(B) (2)

where σo is the flow stress (average between yield stress and ultimate tensile strength) and B is sheet or plate thickness. Currently, the range of the constraint-loss regime (rate at the start of transition and rate at the ending of transition) and the associated constraint factors have to be determined by a trial-and-error method from test data under variable-amplitude loading. The objective of the current study is to “experimentally” determine the constraint-loss regime from constant-amplitude tests by measuring crack-opening stresses under low stress ratio (R = 0 or 0.1) conditions. In addition, it has been determined that the crack-growth delays after a single-spike overload may be caused by constraint-loss behavior. Thus, experiments on both 2024-T3 and 7075-T6 thin-sheet aluminum alloys will be conducted to measure the constraint-loss regime and to conduct repeated single-spike overload tests on M(T) specimens. A method will be developed to experimentally determine the constraint-loss regime either by measurements and/or by single-spike overload tests.

A-10 DTA Update - Correlation of the Willenborg Retardation parameter (SOLR)
Kaylon Anderson - USAF, A-10 ASIP Analysis Group

B-52 spectrum development and validation for organic DTA support
Brian Boeke - USAF, A-10 ASIP Analysis Group

Reconstruction of B-52 DTA Using AFGROW
Casey Scott - Modern Technology Solutions, Inc.

Solution for Combinations of Corner and Straight Through Cracks At Hole
James Lambert, Alex Litvinov, Yevhen Saltovets - LexTech, Inc.

Fatigue Loads & Spectrum Development Overview
James Burd - Aeronautica

Harnessing the Power of AFGROW in a Commercial Environment - New Capabilities and Post Processing Techniques
Reinier de Rijck - Gulfstream Aerospace Corporation

Continuing Damage Testing and Modeling
Matt Andrus - USAF, T-38 Structural Integrity & Analysis Group

A primary goal of this project was to generate continuing damage test data for comparison to different continuing damage modeling approaches. Two different coupon forms were fatigue tested to specimen failure with crack length measurements taken throughout the testing process. The first sample form was manufactured with an offset hole and had two cracks embedded on each side of the hole. The flaw size closer to the free edge measured 0.050-in., while the crack opposite the short ligament side measured 0.005-in. These coupons more closely replicate the continuing damage model process. The second coupon form had a severed ligament from a previous test project. No artificial flaw was embedded on the side of the hole opposite the short ligament. Several models, including the currently used USAF approach, were compared with the test data.

Multisite Damage Solution
James Harter - LexTech, inc.

Determination of bearing stress equivalent width
Luciano Smith*, Ghadir Haikal*, and Kaylon Anderson** - *SwRI, ** USAF, A-10 ASIP Analysis Group

Spectrum manager overview
Matthew Gross - LexTech, Inc.

This presentation will give an overview of the upcoming Spectrum Manager v 1.2. Some of the features include Spectrum Generation from Exceedance data, a new preview selector and spectrum chart, improved application speed, and COM support.

Implementation of Commercially Available MPFM Codes Within Existing Crack Growth Analysis Toolsets
Juan Perez-Narvaez, Cassidy Fitzpatrick - Northrop Grumman

BAMpF Consortium Group Meeting
Joshua Hodges - Hill Engineering

The previous workshop proceedings are available online ↷