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Impact Damage Characterization And Damage Tolerance Of Composite Sandwich Airframe Structures
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Book Synopsis Impact Damage Characterization and Damage Tolerance of Composite Sandwich Airframe Structures by :
Download or read book Impact Damage Characterization and Damage Tolerance of Composite Sandwich Airframe Structures written by and published by . This book was released on 2002 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: The impact responses and the damage states in flat composite sandwich panels with thin face sheets were investigated in Phase I and were found to be dependent on the diameter of the spherical steel impactor. The residual strength of impact-damaged sandwich panels under static in-plane compressive loads was reported to be dependent on the nature of the damage state. The impact damage due to blunt impactors is difficult to detect in service and depending on the size of the damage, can degrade the residual strength more than a punctured skin. The detectability of impact damage states using different field inspection techniques was experimentally investigated for different facesheet and core combinations. The impact damage in honeycomb core sandwich panels was better detected using instruments that exploit the local vibrational characteristics of the sandwich structure, while the damage in foam core panels was more amenable to acoustic-based techniques. The effect of facesheet stiffness on the sensitivity of the field inspection techniques was investigated and the results are reported. The behavior of the sandwich panels with impact damage and subjected to the in-plane static compressive loads was investigated in detail. The impact damage behaved in a characteristic sequence of events leading to contrasting final failure modes. The sequence of events was found to be dependent on the facesheet stiffness and the transverse compressive properties of the core material. The effects of panel curvature on the impact damage resistance of sandwich panels were experimentally investigated for limited sandwich configurations. The effects of the radius of cylindrical panels, boundary conditions, facesheet type, and core type were also examined. The decreasing radius of curvature increased the global bending stiffness but decreased the local contact stiffness due to the radial compressive properties of the honeycomb core.
Book Synopsis Damage Tolerance of Composite Sandwich Airframe Structures by : J. S. Tomblin
Download or read book Damage Tolerance of Composite Sandwich Airframe Structures written by J. S. Tomblin and published by . This book was released on 2005 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: The behavior of sandwich panels with open holes subjected to in-plane tensile and compressive loads were investigated experimentally. The objective of this study was to establish whether the open-hole damage was more severe compared to an impact damage of equal planar size. The experimental results indicated that the open holes are more severe when compared to impact damage created with different impactor sizes. Comparison with past data revealed that residual strengths of impact damaged sandwich panels tend to approach that of the open hole with increasing residual indentation depth.
Book Synopsis Damage Tolerance of Composite Sandwich Airframe Structures by :
Download or read book Damage Tolerance of Composite Sandwich Airframe Structures written by and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The behavior of sandwich panels with open holes subjected to in-plane tensile and compressive loads were investigated experimentally. The objective of this study was to establish whether the open-hole damage was more severe compared to an impact damage of equal planar size. The experimental results indicated that the open holes are more severe when compared to impact damage created with different impactor sizes. Comparison with past data revealed that residual strengths of impact damaged sandwich panels tend to approach that of the open hole with increasing residual indentation depth.
Book Synopsis Analysis of the mechanical response of impact loaded composite sandwich structures with focus on foam core shear failure by : Tim Berend Block
Download or read book Analysis of the mechanical response of impact loaded composite sandwich structures with focus on foam core shear failure written by Tim Berend Block and published by Logos Verlag Berlin GmbH. This book was released on 2014 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sandwich structures are an economically and structurally efficient way of designing large integral composite parts. In the aerospace industry pre-impregnated face sheets and honeycomb core structures can be considered as industry standard while e.g. naval structures and wind turbine blades typically use vacuum infusion technology with polymer foam cores. Application of the less costly infusion technology in the aeronautical industry requires a thorough understanding of the damage tolerance including low velocity impact as a frequent source of damaging events. At low impact energies damage in composite foam core sandwich structures is limited to core crushing and local face sheet delaminations. Higher impact energies may initiate the competing failure modes face sheet rupture and core shear failure depending on impact, geometric and material parameters. Face sheet rupture leads to severe local damage with typically good visibility, while core shear failure leads to cracks and rear face sheet debonding of the foam core with less visibility. This work investigates the low velocity impact response of sandwich structures with carbon fiber reinforced plastic (CFRP) face sheets and a polymeric foam core using experiments at room temperature and at -55° Celsius. An analytically derived failure mode map is presented as a simple tool for design guidelines while the explicit finite element method is applied for a more detailed description of the sandwich impact process. Both models are used to analyze the impact response and describe relevant sensitivity parameters of sandwich structures.
Book Synopsis Damage Tolerance Characterization of Sandwich Composites Using Response Surfaces by :
Download or read book Damage Tolerance Characterization of Sandwich Composites Using Response Surfaces written by and published by . This book was released on 2002 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modeling the Effect of Damage in Composite Structures by : Christos Kassapoglou
Download or read book Modeling the Effect of Damage in Composite Structures written by Christos Kassapoglou and published by John Wiley & Sons. This book was released on 2015-05-06 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensively covers new and existing methods for the design and analysis of composites structures with damage present Provides efficient and accurate approaches for analysing structures with holes and impact damage Introduces a new methodology for fatigue analysis of composites Provides design guidelines, and step by step descriptions of how to apply the methods, along with evaluation of their accuracy and applicability Includes problems and exercises Accompanied by a website hosting lecture slides and solutions
Book Synopsis Damage Tolerance of Composite Sandwich Structures by :
Download or read book Damage Tolerance of Composite Sandwich Structures written by and published by . This book was released on 2000 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Damage Tolerance of Composite Sandwich Airframe Structures - Additional Results by : J. S. Tomblin
Download or read book Damage Tolerance of Composite Sandwich Airframe Structures - Additional Results written by J. S. Tomblin and published by . This book was released on 2005 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Damage Tolerance in Advanced Composites by : Golam Newaz
Download or read book Damage Tolerance in Advanced Composites written by Golam Newaz and published by Routledge. This book was released on 2018-12-13 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: This recent book provides a detailed presentation of damage tolerance assessment and characterization methods for advanced composites, as well as an examination of the role of damage tolerance in the design of composites. Included are analytical models for different types of damage in different composite materials. Tables provide helpful reference
Book Synopsis Review of Damage Tolerance for Composite Sandwich Airframe Structures by :
Download or read book Review of Damage Tolerance for Composite Sandwich Airframe Structures written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of composite sandwich construction is rapidly increasing in current and future airframe designs especially for general aviation aircraft and rotorcraft. Typically, sandwich constructions for these applications use thin-gage composite facesheets (0.020" to 0.045") which are cocured to honeycomb and foam cores. Due to the nature of these structures, damage tolerance is more complex than conventional laminated structures. Besides typical damage concerns such as through penetration and delamination, additional modes including core crushing and facesheet debonding must also be addressed. This complicates the certification process by introducing undefined Allowable Damage Limits (ADL) and Critical Damage Thresholds (CDT) as related to the ultimate and limit load carrying capability of the structure. This document provides a background review of previous damage tolerance investigations including an overview of traditional metallic damage tolerance methodologies. illustrative summaries are presented which show the scope of previous investigation parameters such as impact energy, facesheet thickness, and core thickness of typical sandwich constructions. Also included is a compilation of damage tolerance certification procedures and regulations taken from FAR Part 23-29 for composite damage tolerance as well as recommendations from associated Advisory Circulars. Past and current airframe industry sandwich constructions which show the scope of current and future sandwich designs were also surveyed. In conclusion, a proposed future research approach and its methodology are presented which should aid in establishing certification guidelines and confidence involving the damage tolerance of sandwich constructions as they apply to general aviation aircraft and rotorcraft.
Book Synopsis Improving Damage Tolerance of Composite Sandwich Structures Subjected to Low Velocity Impact Loading by : Ravi B. Gondaliya
Download or read book Improving Damage Tolerance of Composite Sandwich Structures Subjected to Low Velocity Impact Loading written by Ravi B. Gondaliya and published by . This book was released on 2016 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sandwich structures with composite facing skins have seen applications in variety of sectors including aerospace and automobile, owning to their high specific mechanical properties. However, there is a need to develop better damage tolerant sandwich structures since conventional composite facing skins exhibit low impact resistance in the transverse direction. Here, composite skin sandwich structures with three different impact resistant core materials were fabricated and tested both experimentally and numerically. Neat CFRP and 2024-T3 aluminum alloy sheets were also investigated. Cores utilizing impact resistant D30® were found to have very favorable weight specific energy absorbing properties at higher impact velocities as compared to those made from Nomex® or Sorbothane® cores. Nonlinear finite element analysis was also performed using Hypermesh/LS-DYNA for 2024-T3 aluminum alloy sheet, neat CFRP and sandwich with Nomex core with CFRP faceskins. Numerical vs Experimental impact results were compared and comments regarding impact behavior of different candidate materials were made. CAI tests were performed for CFRP sandwich structures. Sandwiches with cores made out of D30® and Sorbothane® showed more ductility when compared with Nomex® core sandwich composite.
Book Synopsis Structural Sandwich Composites by : Composite Materials Handbook – 17 (CMH-17)
Download or read book Structural Sandwich Composites written by Composite Materials Handbook – 17 (CMH-17) and published by SAE International. This book was released on 2013-09-18 with total page 353 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last volume of this six-volume compendium is an update to the cancelled Military Handbook 23, which was prepared for use in the design of structural sandwich polymer composites, primarily for flight vehicles. The information presented includes test methods, material properties, design and analysis techniques, fabrication methods, quality control and inspection procedures, and repair techniques for sandwich structures in military and commercial vehicles. The Composite Materials Handbook, referred to by industry groups as CMH-17, is a six-volume engineering reference tool that contains over 1,000 records of the latest test data for polymer matrix, metal matrix, ceramic matrix, and structural sandwich composites. CMH-17 provides information and guidance necessary to design and fabricate end items from composite materials. It includes properties of composite materials that meet specific data requirements as well as guidelines for design, analysis, material selection, manufacturing, quality control, and repair. The primary purpose of the handbook is to standardize engineering methodologies related to testing, data reduction, and reporting of property data for current and emerging composite materials. It is used by engineers worldwide in designing and fabricating products made from composite materials.
Book Synopsis Impact Resistance and Damage Tolerance of Composite Sandwich Panels by : Pui Ho Wilson Tsang
Download or read book Impact Resistance and Damage Tolerance of Composite Sandwich Panels written by Pui Ho Wilson Tsang and published by . This book was released on 1994 with total page 868 pages. Available in PDF, EPUB and Kindle. Book excerpt: Work was conducted to better understand the damage created in sandwich panels subjected to indentation/impact loading and the subsequent failure process under compressive loads. Three different damage states were created by indenting sandwich panels to a 3 mm indentation depth with indentors of three different diameters: 12.7 mm, 25.4 mm, and 38.1 mm. The sandwich panels were 89 mm wide and 356 mm long with (0/90) and (±45) facesheets made from AW193/3501-6 graphite/epoxy plain weave fabric. The Nomex honeycomb core has a density of 48 kg/m3 , a thickness of 25.4 mm, and a cell size of 3.2 mm. The damage states were characterized by various techniques in terms of geometric facesheet damage (shape of permanent dimple as a result of indentation), material facesheet damage (fiber damage, delaminations, and matrix cracks), and core damage (buckled/crushed cell walls). Damage inspection shows that the permanent dimple is deeper, more localized, and contains more extensive material facesheet damage for the smaller indentor diameter. Based on the damage characterization results, specimens with simulated damage types were designed and manufactured to separately model the core damage and geometric facesheet damage (simulated core damage) and the material facesheet damage (simulated facesheet damage) observed in the indented specimens. Uniaxial compression tests were conducted to failure and monitored with the shadow moire method to obtain quantitative measurements of the out-of-plane deformation of the dimple. Existing analytical models were adapted to predict the damage propagation and the residual strengths of the specimens tested. The failure mechanism of specimens with simulated core damage and those with static indentation damage is via dimple propagation primarily perpendicular to the loading direction, followed by catastrophic failure in the form of facesheet fracture across the width of the specimens. The dimple propagation is driven by load redistribution in the presence of out-of-plane eccentricity (i.e. the dimple), a combination which causes local bending of the facesheet and progressive core crushing perpendicular to the loading direction. The dimple propagation model successfully predicts the evolving dimple profiles for specimens with (0/90) facesheets and simulated core damage. Material facesheet damage and nonlinear stress-strain behavior of the ( 45) facesheets cause a local reduction in facesheet stiffness which induces more severe load redistribution and, hence, greater rates of dimple propagation. Such local reduction in facesheet stiffness needs to be included in the dimple propagation model to improve the predictions for specimens with material facesheet damage and/or (±45) facesheets. The final failure in specimens with static indentation damage and simulated core damage is caused by high longitudinal stress due to load redistribution in the facesheet within the dimple. The applied stress levels at which the calculated peak longitudinal membrane stress along the centerline through the dimple and perpendicular to the loading direction reaches the compressive strength of the corresponding undamaged specimens correlates well with the residual strengths of specimens with (0/90) facesheets and simulated core damage. Failure predictions for specimens with (0/90) facesheets and static indentation damage is not as good because the model does not account for the interaction between the geometric facesheet damage, core damage, and material facesheet damage. Visibility of the dimple and dimple depth alone are not good metrics for damage because barely visible damage can cause equally significant or greater reduction in compressive strength as easily visible damage. Proper three-dimensional damage characterization of all damage types is necessary to facilitate better assessment of damage tolerance.
Book Synopsis Damage-Tolerance Characteristics of Composite Fuselage Sandwich Structures with Thick Facesheets by : David M. McGowan
Download or read book Damage-Tolerance Characteristics of Composite Fuselage Sandwich Structures with Thick Facesheets written by David M. McGowan and published by . This book was released on 1997 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Defects and Damage in Composite Materials and Structures by : Rikard Benton Heslehurst
Download or read book Defects and Damage in Composite Materials and Structures written by Rikard Benton Heslehurst and published by CRC Press. This book was released on 2014-04-21 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: The advantages of composite materials include a high specific strength and stiffness, formability, and a comparative resistance to fatigue cracking and corrosion. However, not forsaking these advantages, composite materials are prone to a wide range of defects and damage that can significantly reduce the residual strength and stiffness of a structure or result in unfavorable load paths. Emphasizing defect identification and restitution, Defects and Damage in Composite Materials and Structures explains how defects and damage in composite materials and structures impact composite component performance. Providing ready access to an extensive, descriptive list of defects and damage types, this must-have reference: Examines defect criticality in composite structures Recommends repair actions to restore structural integrity Discusses failure modes and mechanisms of composites due to defects Reviews NDI processes for finding and identifying defects in composite materials Relating defect detection methods to defect type, the author merges his experience in the field of in-service activities for composite airframe maintenance and repair with indispensable reports and articles on defects and damage in advanced composite materials from the last 50 years.
Book Synopsis Damage Tolerance Characterisitics of Composite Sandwich Structures by : L. Lazzeri
Download or read book Damage Tolerance Characterisitics of Composite Sandwich Structures written by L. Lazzeri and published by . This book was released on 2000 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current damage tolerance requirements impose strict constraints on the design of composite aircraft structures, since the various forms of defects taken into consideration must show no-growth' characteristics in the environmental and loading conditions expected in the operative life. A research activity was carried out by Agusta, in collaboration with the University of Pisa, with the purpose of assessing the damage tolerance characteristics of typical composite sandwich structures used by the helicopter industry. A particular effort was dedicated to the study of delamination growth under compression loading, a basic step for understanding the damage tolerance behavior of composite structures. The results of the numerical analysis carried out show that G, the Strain Energy Release Rate, is a suitable parameter for describing the behavior of the delamination, but it is essential to consider its partition according to the fundamental modes.
Book Synopsis Damage Tolerance of Metallic Aircraft Structures by : Sérgio M. O. Tavares
Download or read book Damage Tolerance of Metallic Aircraft Structures written by Sérgio M. O. Tavares and published by Springer. This book was released on 2018-08-06 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a state-of-the-art review of the fail-safe and damage tolerance approaches, allowing weight savings and increasing aircraft reliability and structural integrity. The application of the damage tolerance approach requires extensive know-how of the fatigue and fracture properties, corrosion strength, potential failure modes and non-destructive inspection techniques, particularly minimum detectable defect and inspection intervals. In parallel, engineering practice involving damage tolerance requires numerical techniques for stress analysis of cracked structures. These evolved from basic mode I evaluations using rough finite element approaches, to current 3D modeling based on energetic approaches as the VCCT, or simulation of joining processes. This book provides a concise introduction to this subject.
