Analysis of Test Methods for Characterizing Skin/Stringer Debonding Failures in Reinforced Composite Panels PDF Download
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Author: PJ. Minguet
Publisher:
ISBN:
Category : Bond strength
Languages : en
Pages : 20
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Book Description
A simple test specimen configuration is proposed to evaluate the bond strength between a skin and secondarily bonded or co-cured stringer or frame when the dominant loading in the skin is flexure along the edge of the frame. The specimen consists of a flange bonded onto a skin, loaded either in a three- or four-point bending test fixture. Two configurations for the flange termination were examined, either square-ended or with a 20° taper. Observations show that failure initiates at the tip of the frame flange, either in the adhesive or in the topmost skin ply. Loads at which failure initiates were recorded, as well as the load at which a delamination propagates along the skin/flange interface. Detailed finite element models were built to examine the stress distribution in that critical area. Two failure modes were considered, failure in the adhesive material due to maximum tensile stress and formation of transverse cracks in the skin topmost ply due to maximum transverse principal tensile stress. When applying the experimentally measured failure initiation loads onto the finite element models, results show that the calculated transverse stress in the top skin ply is very close to the transverse strength of a unidirectional tape ply for all the configurations tested. Results also show that the stress levels in the adhesive are almost identical for all the configurations tested.
Author: PJ. Minguet
Publisher:
ISBN:
Category : Bond strength
Languages : en
Pages : 20
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Book Description
A simple test specimen configuration is proposed to evaluate the bond strength between a skin and secondarily bonded or co-cured stringer or frame when the dominant loading in the skin is flexure along the edge of the frame. The specimen consists of a flange bonded onto a skin, loaded either in a three- or four-point bending test fixture. Two configurations for the flange termination were examined, either square-ended or with a 20° taper. Observations show that failure initiates at the tip of the frame flange, either in the adhesive or in the topmost skin ply. Loads at which failure initiates were recorded, as well as the load at which a delamination propagates along the skin/flange interface. Detailed finite element models were built to examine the stress distribution in that critical area. Two failure modes were considered, failure in the adhesive material due to maximum tensile stress and formation of transverse cracks in the skin topmost ply due to maximum transverse principal tensile stress. When applying the experimentally measured failure initiation loads onto the finite element models, results show that the calculated transverse stress in the top skin ply is very close to the transverse strength of a unidirectional tape ply for all the configurations tested. Results also show that the stress levels in the adhesive are almost identical for all the configurations tested.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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Book Description
The objective of this work was to investigate the fatigue damage mechanisms and to identify the influence of skin stacking sequence in carbon epoxy composite bonded skin/stringer constructions. A simple 4-point-bending test fixture originally designed for previously performed monotonic tests was used to evaluate the fatigue debonding mechanisms between the skin and the bonded frame when the dominant loading in the skin is flexure along the edge of the frame. The specimens consisted of a tapered flange, representing the stringer, bonded onto a skin. Based on the results of previous monotonic tests two different skin lay-ups in combination with one flange lay-up were investigated. The tests were performed at load levels corresponding to 40%, 50%, 60%, 70%, and 80% of the monotonic fracture loads. Microscopic investigations of the specimen edges were used to document the onset of matrix cracking and delamination, and subsequent fatigue delamination growth. Typical damage patterns for both specimen configurations were identified. The observations showed that failure initiated near the tip of the flange in the form of matrix cracks at one of two locations, one in the skin and one in the flange. The location of the 90 deg flange and skin plies relative to the bondline was identified as the dominant lay-up feature that controlled the location and onset of matrix cracking and subsequent delamination. The fatigue delamination growth experiments yielded matrix cracking and delamination onset as a function of fatigue cycles as well as delamination length as a function of the number of cycles.
Author:
Publisher:
ISBN:
Category : Aerodynamic measurements
Languages : en
Pages : 62
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Book Description
Author: C. T. Sun
Publisher: CRC Press
ISBN: 0849315018
Category : Technology & Engineering
Languages : en
Pages : 1685
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Book Description
Author: Christos Kassapoglou
Publisher: John Wiley & Sons
ISBN: 1119957060
Category : Technology & Engineering
Languages : en
Pages : 303
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Book Description
Design and Analysis of Composite Structures enables graduate students and engineers to generate meaningful and robust designs of complex composite structures. Combining analysis and design methods for structural components, the book begins with simple topics such as skins and stiffeners and progresses through to entire components of fuselages and wings. Starting with basic mathematical derivation followed by simplifications used in real-world design, Design and Analysis of Composite Structures presents the level of accuracy and range of applicability of each method. Examples taken from actual applications are worked out in detail to show how the concepts are applied, solving the same design problem with different methods based on different drivers (e.g. cost or weight) to show how the final configuration changes as the requirements and approach change. Provides a toolkit of analysis and design methods to most situations encountered in practice, as well as analytical frameworks and the means to solving them for tackling less frequent problems. Presents solutions applicable to optimization schemes without having to run finite element models at each iteration, speeding up the design process and allowing examination of several more alternatives than traditional approaches. Includes guidelines showing how decisions based on manufacturing considerations affect weight and how weight optimization may adversely affect the cost. Accompanied by a website at www.wiley.com/go/kassapoglou hosting lecture slides and solutions to the exercises for instructors.
Author: Srinivasan Sridharan
Publisher: Elsevier
ISBN: 1845694821
Category : Technology & Engineering
Languages : en
Pages : 787
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Book Description
Given such advantages as low weight compared to strength and toughness, laminated composites are now used in a wide range of applications. Their increasing use has underlined the need to understand their principal mode of failure, delamination. This important book reviews key research in understanding and preventing delamination.The first part of the book reviews general issues such as the role of fracture mechanics in understanding delamination, design issues and ways of testing delamination resistance. Part two describes techniques for detecting and characterising delamination such as piezoelectric sensors, the use of lamb waves and acoustic emission techniques. The next two sections of the book discuss ways of studying and modelling delamination behaviour. The final part of the book reviews research on delamination behaviour in particular conditions such as shell and sandwich structures, z-pin bridging and resin bonding.With its distinguished editor and international team of contributors, Delamination behaviour of composites is a standard reference for all those researching laminated composites and using them in such diverse applications as microelectronics, aerospace, marine, automotive and civil engineering. - Reviews the role of fracture mechanics in understanding delamination, design issues and ways of testing delamination resistance - Discuss ways of studying and modelling delamination behaviour - A standard reference for all those researching laminated composites
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 182
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Book Description
Author: Ravi B. Deo
Publisher: ASTM International
ISBN: 080312404X
Category :
Languages : en
Pages : 419
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Author: Bryan Harris
Publisher: Elsevier
ISBN: 1855738570
Category : Technology & Engineering
Languages : en
Pages : 765
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Book Description
This major handbook is the first authoritative survey of current knowledge of fatigue behaviour of composites. It deals in detail with a wide range of problems met by designers in the automotive, marine and structural engineering industries. Compiled from the contributions of some of the best-known researchers in the field, it provides an invaluable, practical and encyclopaedic handbook covering recent developments. - Comprehensively discusses the problems of fatigue in composites met by designers in the aerospace, marine and structural engineering industries - Provides a general introduction on fatigue in composites before reviewing current research on micromechanical aspects - Analyses various types of composites with respect to fatigue behaviour and testing and provides in-depth coverage of life-prediction models for constant variable stresses
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 60
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Book Description
