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.

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.

Engineered Repairs of Composite Structures provides a detailed discussion, analysis, and procedures for effective and efficient repair design of advanced composite structures. It discusses the identification of damage types and the effect on structural integrity in composite structures, leading to the design of a repair scheme that focusses on the restoration of the structural integrity and damage tolerance. This book teaches the reader to better understand effective and efficient repair design, allowing for more structurally effective repairs of damaged composite structures. It also discusses the application of the repair and what is needed in the forming of the composite repair to meet the engineering design requirements. Aimed at materials engineers, mechanical engineers, aerospace engineers, and civil engineers, this practical work is a must have for any industry professional working with composite structures.

Over 8,300 pages .... Just a SAMPLE of the CONTENTS: NONDESTRUCTIVE INSPECTION METHODS. Published by the Departments of the Army, Navy and Air Force on 1 March 2000 - 771 pages and June 2005 - 762 pages; Metallic Materials and Elements for Aerospace Vehicle Structures 1,733 pages Designing and Developing Maintainable Products and Systems - Revision A 719 pages Sampling Procedures and Tables for Inspection by Attributes 75 pages Nondestructive Testing Acceptance Criteria 88 pages Environmental Stress Screening Process for Electronic Equipment 49 pages Handbook for Reliability Test Methods, Plans, and Environments for Engineering, Development, Qualification, and Production - Revision A 411 pages Human Engineering - Revision F 219 pages Sampling Procedures and Tables for Life and Reliability Testing (Based on Exponential Distribution) 77 pages Test Method Standard: Electronic and Electrical Component Parts 191 pages Reliability Testing for Engineering Development, Qualification and Production - Revision D 47 pages Electroexplosive Subsystem Safety Requirements and Test Methods for Space Systems (150 pages, 8.64 MB) Reliability Prediction of Electronic Equipment- Notice F 205 pages Reliability Program for Systems and Equipment Development and Production - Revision B 88 pages Electronic Discharge Control Handbook for Protection of Electrical and Electronic Parts, Assemblies and Equipment (Excluding Electrically Initiated Explosive Devices) - Revision B 171 pages Electrical Grounding for Aircraft Safety 290 pages Fuze and Fuze Components, Environmental and Performance Tests for - Revision C 295 pages Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment - Revision E 253 pages Maintainability Verification/Demonstration/Evaluation - Revision A 64 pages Failure Rate Sampling Plans and Procedures - Revision C 41 pages Maintainability Prediction 176 pages Definition of Terms for Reliability and Maintainability - Revision C 18 pages Semiconductor Devices 730 pages Reliability Modeling and Prediction - Revision B 85 pages Established Reliability and High Reliability Qualified Products List (QPL) Systems For Electrical, Electronic, and Fiber Optic Parts Specifications - Revision F 17 pages Environmental Test Methods and Engineering Guidelines 416 pages) Test Methods for Electrical Connectors - Revision A 129 pages Environmental Engineering Considerations and Laboratory Tests - Revision F 539 pages System Safety Program Requirements 117 pages Test Method Standard Microcircuits - Revision E 705 pages Test Method Standard Microcircuits - Revision F 708 pages Procedures for Performing a Failure Mode Effects and Criticality Analysis - Revision A 54 pages

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.

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.