Bonded Repairs Archives - ESRD https://www.esrd.com/product-tag/bonded-repairs/ Engineering Software Research and Development, Inc. Thu, 07 Dec 2023 16:59:08 +0000 en-US hourly 1 https://wordpress.org/?v=6.6.2 https://www.esrd.com/wp-content/uploads/cropped-SC_mark_LG72ppi-32x32.jpg Bonded Repairs Archives - ESRD https://www.esrd.com/product-tag/bonded-repairs/ 32 32 Experimental Validation of DTA Modeling of Bonded Wing Skin Repairs https://www.esrd.com/resource-library/product/experimental-validation-of-dta-modeling-of-bonded-wing-skin-repairs/ Thu, 07 Dec 2023 16:41:37 +0000 https://www.esrd.com/?post_type=product&p=30469 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.]]>
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]]> DTA of Bonded Repairs on the Wing Skin of the C130 Using Finite Elements https://www.esrd.com/resource-library/product/dta-of-bonded-repairs-on-the-wing-skin-of-the-c130-using-finite-elements/ Thu, 08 Dec 2022 18:01:39 +0000 https://www.esrd.com/?post_type=product&p=26592 Abstract: Current methodologies for the design and application of repairs to damaged sections of aircraft wing skin can be lacking in analytical support, relying instead on accumulated practical experience to determine the effectiveness of a given patch design. These methods are, by their nature, effective, being based on observation, but inefficient, requiring a knowledge base acquired over years of experience. This can make sustainment organizations inflexible and vulnerable to gaps in knowledge between newer members and more seasoned experts. This approach is also problematic in its potential for wasted effort and material, applying repairs that may be more intensive than is required for a given situation. These problems can all be addressed by the introduction of an accessible, robust analysis methodology cast in the form of an Engineering Simulation Application for the verification of a repair’s performance qualities prior to an actual aircraft application. The finite element method is ideally suited to provide an analysis procedure for this type of problems that can be used by analysts with widely varying degrees of expertise both in numerical simulation and bonded repair application. This presentation will outline a proposed methodology for utilizing finite element analysis to assess the effectiveness of a given bonded repair. Originally presented as a technical paper at the 2022 ASIP conference in Phoenix, AZ.]]>
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]]> ASIP 2022 Training – Best Practices for the Modeling and Analysis of Bonded Doubler Repairs https://www.esrd.com/resource-library/product/asip-2022-training-best-practices-for-the-modeling-and-analysis-of-bonded-doubler-repairs/ Mon, 05 Dec 2022 15:01:02 +0000 https://www.esrd.com/?post_type=product&p=26512 Abstract: this 2-hour training course, originally presented at the ASIP 2022 conference in Phoenix, AZ, explored the following topics:
  • StressCheck’s FEA technology implementation enabling modeling of very thin domains, including adhesive layers with 3D-solid elements.
  • Best practices and guidelines for modeling and analyzing 3D bonded repair doubler variations (e.g. racetrack/rectangular, circular/elliptical, tapered, metallic, ply-by-ply, homogenized, etc.) for circular cutouts and grindouts.
  • Performing “what if?” logic-driven studies of a digital 3D bonded repair handbook solution via StressCheck API-powered Engineering Simulation App, in which user-defined input data is passed from Python or Excel VBA to StressCheck Professional to perform scripted “on-the-fly” model adjustments and repair-oriented computations.
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]]> Application Brief: Detailed Analysis of Bonded Repairs https://www.esrd.com/resource-library/product/application-brief-detailed-analysis-of-bonded-repairs/ Tue, 22 Nov 2022 14:48:26 +0000 https://www.esrd.com/?post_type=product&p=26453 Aircraft are commonly being flown well past their original expected service life, and the value derived from improving the productivity and reliability of DaDT analysis functions to support the inspection, maintenance, repair, and life-extension of today’s aerostructures is substantial. StressCheck's implementation of numerical simulation is designed to support solution verification, an essential technical requirement of Simulation Governance. The implementation makes it possible to encapsulate complexity, improve productivity, contain costs, and ensure the reliability of results for the expert simulation analyst as well as the non-FEA expert DaDT engineer.]]>
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]]> StressCheck Demo: Bonded Composite Repair Patch for Cracked Hole https://www.esrd.com/resource-library/product/stresscheck-demo-bonded-composite-repair-patch-for-cracked-hole/ Thu, 30 May 2019 00:55:43 +0000 https://esrd.com/?post_type=product&p=10602 Abstract: Modeling and linear analysis of an adhesively-bonded composite doubler repair patch over a hole with an elliptical part-thru crack. The goal is to reduce the SIF's at the crack front and extend the life of the plate.]]>

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]]> StressCheck Tutorial: Laminated Composite Repair Patch Part III – Geometric Nonlinear Analysis https://www.esrd.com/resource-library/product/stresscheck-tutorial-laminated-composite-repair-patch-part-iii-geometric-nonlinear-analysis/ Mon, 22 Oct 2018 21:11:42 +0000 https://esrd.com/?post_type=product&p=8171 Abstract: Modeling a laminated composite repair patch. Rectangular plate with circular cutout bonded with a rectangular laminated composite repair patch. Part III: comparison between linear and geometric nonlinear solutions. StressCheck Tutorial: Laminated Composite Repair Patch Part II - Materials, BC's & Results]]>
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]]> StressCheck Tutorial: Laminated Composite Repair Patch Part II – Materials, BC’s & Results https://www.esrd.com/resource-library/product/stresscheck-tutorial-laminated-composite-repair-patch-part-ii-materials-bcs-results/ Mon, 22 Oct 2018 15:08:54 +0000 https://esrd.com/?post_type=product&p=8155 Abstract: Modeling a laminated composite repair patch. Rectangular plate with circular cutout bonded with a rectangular laminated composite repair patch. Part II: material definition and assignment via automatic lamination, application of boundary conditions, solution by p-extension and live dynamic results. StressCheck Tutorial: Laminated Composite Repair Patch Part I - Geometry & Meshing]]>
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]]> StressCheck Tutorial: Laminated Composite Repair Patch Part I – Geometry & Meshing https://www.esrd.com/resource-library/product/stresscheck-tutorial-laminated-composite-repair-patch-part-1-geometry-and-meshing/ Fri, 19 Oct 2018 20:47:41 +0000 https://esrd.com/?post_type=product&p=8149 Abstract: Modeling a laminated composite repair patch. Rectangular plate with circular cutout bonded with a rectangular laminated composite repair patch. Part I: parametric geometry modeling and meshing with hexas and pentas.]]>
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]]> Conference Presentation: A System for Simulation Governance of Engineered Repairs of Composite Aircraft Structures https://www.esrd.com/resource-library/product/conference-presentation-system-simulation-governance-engineered-repairs-composite-aircraft-structures/ Thu, 02 Mar 2017 22:28:42 +0000 http://esrd.com/?post_type=product&p=2286 Abstract: Modern military aircraft = composite skins + metallic sub-structure. Verification of structural integrity of standard repairs is costly, and requires structural and strength analysis. Traditional closed-form analysis techniques are unrepresentative and unsuitable, but construction of detailed finite element models requires Finite Element Analysis (FEA) expertise. Therefore, computational system with these requirements is needed to accelerate decision-making:
  • Validated/certified methods
  • Closed-form and FEA-based
  • Readily employed
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