1、 NOT MEASUREMENTSENSITIVECMH-17-6 Volume 6 of 6July 2013COMPOSITE MATERIALS HANDBOOKVOLUME 6. STRUCTURAL SANDWICH COMPOSITESCopyright 2013 - Composite Materials Handbook 17 (CMH-17). All rights reserved. Unauthorized duplication or distribution may violate the Copyright Laws of the United States and
2、 of other jurisdictions. Published by SAE International on behalf of CMH-17,a division of Wichita State University.Copyright 2013 SAE International eISBN: 978-0-7680-8062-9 CMH-17-6 Volume 6, Foreword ii FOREWORD The Composite Materials Handbook, CMH-17, provides information and guidance necessary t
3、o design and fabricate structural components from composite materials. Its primary purposes are a) the standardi-zation of engineering data development methodologies related to testing, data reduction, and data report-ing of property data for current and emerging composite materials, b) guidance on
4、material and process specifications and procedures for utilization of the material data presented in the handbook, and c) meth-odologies for the design, analysis, certification, manufacture, and field support of composite structures. In support of these objectives, the handbook includes composite ma
5、terials properties that meet specific data requirements. The Handbook therefore constitutes an overview of the field of composites technology and engineering, an area that is advancing and changing rapidly. As a result, the document will be continually revised as sections are added or modified to re
6、flect advances in the state-of-the-art. CMH-17 Mission The Composite Materials Handbook organization creates, publishes and maintains proven, reliable engi-neering information and standards, subjected to thorough technical review, to support the development and use of composite materials and structu
7、res. CMH-17 Vision The Composite Materials Handbook will be the authoritative worldwide focal point for technical infor-mation on composite materials and structures. Goals and Objectives to Support CMH-17 Mission x To periodically meet with experts from the field to discuss critical technical issues
8、 for composite structural applications, with an emphasis on increasing overall product efficiency, quality and safety. x To provide comprehensive, practical engineering guidance that has proven reliable for the design, fabrication, characterization, test and maintenance of composite materials and st
9、ructures. x To provide reliable data, linked to control of processes and raw materials, thereby being a com-prehensive source of material property basis values and design information that can be shared within the industry. x To provide a resource for composite material and structure education with e
10、xamples, applications and references to supporting engineering work. x To establish guidelines for use of information in the Handbook, identifying the limitations of the data and methods. x To provide guidance on references to proven standards and engineering practices. x To provide for periodic upd
11、ates to maintain the all-inclusive nature of the information. x To provide information in formats best-suited for user needs. x To serve the needs of the international composites community through meetings and dialogue be-tween member industries, which use teamwork and the diverse member engineering
12、 skills to pro-vide information for the handbook. CMH-17-6 Volume 6, Foreword iii Notes 1. Every effort has been made to reflect the latest information on polymer (organic), metal, and ce-ramic composites. The handbook is continually reviewed and revised to ensure it is complete and current. 2. CMH-
13、17 provides guidelines and material properties for polymer (organic), metal, and ceramic matrix composite materials. The first three volumes of this handbook currently focus on, but are not limited to, polymeric composites intended for aircraft and aerospace vehicles. Metal matrix composites (MMC),
14、ceramic matrix composites (CMC) including carbon-carbon composites (C-C), and sandwich composites are covered in Volumes 4, 5, and 6, respectively. 3. The information contained in this handbook was obtained from materials producers, industry companies and experts, reports on Government sponsored res
15、earch, the open literature, and by contract with research laboratories and those who participate in the CMH-17 coordination activity. The information in this handbook has undergone vigorous technical review and was subject to membership vote. 4. Beneficial comments (recommendations, additions, delet
16、ions) and any pertinent data which may be of use in improving this document should be addressed to: CMH-17 Secretariat, Materials Sciences Corporation, 135 Rock Road, Horsham, PA 19044, by letter or email, hand-bookmaterials-. ACKNOWLEDGEMENT Volunteer committee members from government, industry, an
17、d academia develop, coordinate and review all the information provided in this handbook. The time and effort of the volunteers and the support of their respective departments, companies, and universities make it possible to insure the handbook re-flects completeness, accuracy, and state-of-the-art c
18、omposite technology. Support necessary for the development and maintenance of the Composite Materials Handbook (CMH-17) are provided by the handbook Secretariat, Materials Sciences Corporation. The primary source of funding for the current Secretariat contract is the Federal Aviation Administration.
19、 CMH-17-6 Volume 6, Foreword / Table of Contents iv TABLE OF CONTENTS Page FOREWORD ii CHAPTER 1 GENERAL INFORMATION . 1 1.1 INTRODUCTION TO THE HANDBOOK . 1 1.2 OVERVIEW OF HANDBOOK CONTENT . 1 1.3 INTRODUCTION . 2 1.4 NOMENCLATURE AND DEFINITIONS 3 1.4.1 Loads, geometry, and material properties 3
20、1.4.1.1 Subscripts . 7 1.4.1.2 Superscripts . 8 1.4.1.3 Assumptions and definitions 8 1.4.2 System of units . 9 REFERENCES . 10 CHAPTER 2 GUIDELINES FOR PROPERTY TESTING . 1 2.1 INTRODUCTION . 1 2.2 DATA REDUCTION AND PRESENTATION 1 2.3 EVALUATION OF CORE MATERIALS . 1 2.3.1 Introduction 1 2.3.2 Mec
21、hanical properties 2 2.3.3 Environmental effects . 2 2.3.4 Test methods 5 2.4 EVALUATION OF CORE-TO-FACE SHEET BONDS . 6 2.4.1 Introduction 6 2.4.2 Mechanical properties 6 2.4.3 Environmental effects . 6 2.4.4 Test Methods 6 2.5 EVALUATION OF FACE SHEET PROPERTIES 7 2.5.1 Introduction 7 2.5.2 Mechan
22、ical properties 7 2.5.3 Environmental effects . 8 2.5.4 Test methods 8 2.6 EVALUATION OF SANDWICH PANELS 8 2.6.1 Introduction 8 2.6.2 Mechanical properties 9 2.6.3 Environmental effects . 9 2.6.4 Damage resistance 9 2.6.5 Damage tolerance 10 2.6.6 Repair . 10 2.6.7 Test methods 10 2.7 EVALUATION OF
23、INSERTS AND FASTENERS 11 2.7.1 Introduction 11 2.7.2 Environmental effects . 11 2.7.3 Test methods 11 2.7.4 Mechanical properties 11 2.8 EVALUATION OF OTHER FEATURES 14 2.8.1 Introduction 14 2.8.2 Mechanical properties 14 2.8.3 Environmental effects . 14 CMH-17-6 Volume 6, Foreword / Table of Conten
24、ts v 2.8.4 Test methods 14 REFERENCES . 16 CHAPTER 3 MATERIAL DATA 1 3.1 CORES . 1 3.1.1 Description of cores . 1 3.1.2 Core specifications . 1 3.1.3 Honeycomb Cores . 2 3.1.4 Cross-banded core. 5 3.1.5 Corrugated core . 6 3.1.6 Waffle-type core . 6 3.1.7 Foam cores 6 3.1.8 Wood cores 7 3.1.9 Core p
25、roperties 8 3.1.9.1 Estimation of core properties . 16 3.2 FACE SHEETS . 17 3.2.1 Description of face sheets 17 3.2.1.1 Adhesively-bonded pre-fabricated face sheets . 17 3.2.1.2 Co-cured or co-bonded face sheets with adhesive . 17 3.2.1.3 Self-adhesive face sheets . 18 3.2.2 Face sheet properties 18
26、 3.3 ADHESIVES 18 3.3.1 Description of adhesives 19 3.3.2 Adhesive specifications 19 3.3.3 Adhesive forms/types and uses . 20 3.3.3.1 Resins from self-adhesive face sheets 20 3.3.3.2 Film adhesives . 20 3.3.3.3 Paste adhesives 20 3.3.3.4 Liquid resins . 21 3.3.3.5 Foaming adhesives . 21 3.3.4 Adhesi
27、ve chemistries . 21 3.3.4.1 Epoxy . 21 3.3.4.2 Bismaleimide . 21 3.3.4.3 Phenols . 22 3.3.4.4 Polyester . 22 3.3.4.5 Polyimide . 22 3.3.5 Adhesive properties . 23 REFERENCES . 24 CHAPTER 4 DESIGN AND ANALYSIS OF SANDWICH STRUCTURES . 1 4.1 INTRODUCTION . 1 4.2 DESIGN AND CERTIFICATION 2 4.2.1 Basic
28、design principles 2 4.2.2 Design process 3 4.2.3 Aircraft damage tolerance 4 4.3 CERTIFICATION . 8 4.3.1 Introduction to certification issues 8 4.3.2 Approach to certification testing . 9 4.3.3 Analysis validation 9 4.3.4 Conformity oversight 9 4.3.5 Nondestructive testing (NDT) . 10 4.3.6 Documenta
29、tion requirements . 10 4.3.7 Continued airworthiness 10 4.4 SANDWICH PANEL FAILURE MODES 10 CMH-17-6 Volume 6, Foreword / Table of Contents vi 4.5 STIFFNESS AND INTERNAL LOADS 13 4.5.1 Beam stiffness analysis 13 4.5.2 Plate stiffness analysis . 16 4.5.3 Combined transverse and in-plane loadings . 18
30、 4.5.4 Face sheet internal loads . 18 4.6 LOCAL STRENGTH ANALYSIS METHODS 19 4.6.1 Face sheet failure . 19 4.6.2 Core shear . 20 4.6.3 Flatwise tension and compression . 22 4.6.4 Flexural core crushing 24 4.6.5 Intracell buckling (dimpling) . 24 4.6.5.1 Sandwich having cellular (honeycomb) core . 25
31、 4.6.5.2 Sandwich having corrugated core . 26 4.6.5.3 Shear intracell buckling . 40 4.6.5.4 Combined compression and shear intracell buckling 40 4.6.6 Face sheet wrinkling 40 4.6.6.1 Wrinkling of sandwich face sheets under edgewise load 40 4.6.6.2 Sandwich with core supporting face sheets continuous
32、ly . 41 4.6.6.3 Sandwich with honeycomb core 44 4.6.6.4 Shear face sheet wrinkling 45 4.6.6.5 Face sheet wrinkling - combined loads . 45 4.6.6.6 Face sheet wrinkling - curved panels 46 4.6.7 Core shear crimping . 49 4.6.8 Attachments and hard points . 49 4.6.8.1 Design of flat circular sandwich pane
33、ls loaded at an insert 49 4.7 FLAT PANEL INTERNAL LOADS AND STRESSES - PRESSURE LOADING 56 4.7.1 Design of flat rectangular sandwich panels under various normal loadings 56 4.7.2 Design of flat sandwich panels under uniformly distributed normal load . 57 4.7.2.1 Determining face sheet thickness, cor
34、e thickness, and core shear modulus for simply supported flat rectangular panels under uniform load . 57 4.7.2.1.1 Use of design charts 68 4.7.2.1.2 Determining core shear stress 70 4.7.2.1.3 Checking procedures 74 4.7.2.2 Determining face sheet thickness, core thickness, and core shear modulus for
35、simply supported flat circular panels under uniform load . 86 4.7.2.2.1 Use of design charts 90 4.7.2.2.2 Determining core shear stress 91 4.7.2.2.3 Checking procedure 92 4.8 CURVED SANDWICH PANEL INTERNAL LOADS AND STRESSES . 92 4.8.1 General equations and analysis method 92 4.9 FLAT PANEL STABILIT
36、Y ANALYSIS METHODS . 95 4.9.1 Buckling of flat rectangular sandwich columns 96 4.9.2 Design of flat rectangular sandwich panels under edgewise compression load 97 4.9.2.1 Determining face sheet thickness 97 4.9.2.2 Determining core thickness and core shear modulus . 97 4.9.2.2.1 Determining minimum
37、value of d . 99 4.9.2.2.2 Determining actual value of d 101 4.9.2.3 Checking procedure for determining buckling stress, Fcr108 4.9.3 Design of flat rectangular sandwich panels under edgewise shear load . 129 4.9.3.1 Determining face sheet thickness 129 4.9.3.2 Determining core thickness and core she
38、ar modulus . 129 4.9.3.2.1 Determining minimum value of d . 131 CMH-17-6 Volume 6, Foreword / Table of Contents vii 4.9.3.2.2 Determining actual value of d 138 4.9.3.3 Checking procedure for determining buckling stress, Fcr. 140 4.9.4 Design of sandwich strips under torsion load 149 4.9.4.1 Determin
39、ing face sheet thickness, core thickness and core shear modulus for sandwich strips of trapezoidal and rectangular cross section . 149 4.9.4.1.1 Determining minimum values of d and t 156 4.9.4.1.2 Determining actual values of d and t . 156 4.9.4.1.3 Checking procedure for sandwich strips of trapezoi
40、dal and rectangular cross section 157 4.9.4.2 Determining face sheet thickness and core shear modulus for sandwich strips of triangular cross section 161 4.9.4.2.1 Determining minimum value of t 163 4.9.4.2.2 Determining actual value of t . 166 4.9.4.2.3 Checking procedure for sandwich strips of tri
41、angular cross section . 166 4.9.5 Design of flat rectangular sandwich panels under edgewise bending moment 168 4.9.5.1 Determining face sheet thickness 169 4.9.5.2 Determining core thickness and core shear modulus . 171 4.9.5.2.1 Determining minimum value of d . 172 4.9.5.2.2 Determining actual valu
42、e of d 175 4.9.5.3 Checking procedure for determining buckling stress, Fcr178 4.10 DESIGN OF FLAT RECTANGULAR SANDWICH PANELS UNDER COMBINED LOADS . 183 4.10.1 Combined load buckling . 183 4.10.1.1 Biaxial compression 183 4.10.1.2 Bending and compression 183 4.10.1.3 Compression and shear 183 4.10.1
43、.4 Bending and shear 184 4.10.2 Combined in-plane and transverse loads 184 4.11 DESIGN OF SANDWICH CYLINDERS 184 4.11.1 Introduction 184 4.11.2 Sandwich cylinders under external radial pressure . 184 4.11.2.1 Determining face sheet thickness, core thickness, and core shear modulus for sandwich cylin
44、ders under external radial pressure. 185 4.11.2.2 Final design . 188 4.11.3 Sandwich cylinders under torsion 193 4.11.3.1 Determining face sheet thickness for sandwich cylinders under torsion 193 4.11.3.2 Determining core thickness and core shear modulus for sandwich cylinders under torsion 194 4.11
45、.3.3 Check to determine whether sideways buckling will occur . 202 4.11.4 Sandwich cylinders under axial compression or bending 204 4.11.4.1 Determining face sheet thickness, core thickness, and core shear modulus . 204 4.11.4.2 Checking procedure for determining cylinder wall buckling stress, Fcr.
46、210 4.11.4.3 Check to determine whether column buckling will occur 210 4.11.5 Sandwich cylinders under combined loads 210 4.11.5.1 Axial compression and external lateral pressure 211 4.11.5.2 Axial compression and torsion 211 4.11.5.3 Torsion and lateral external or internal pressure . 211 4.12 FINI
47、TE ELEMENT MODELING OF SANDWICH STRUCTURE 211 4.12.1 Introduction 211 4.12.2 Global models 212 CMH-17-6 Volume 6, Foreword / Table of Contents viii 4.12.3 Layered models 213 4.12.4 Solid models . 214 4.12.5 Sandwich element models . 215 4.13 OPTIMUM SANDWICH . 215 4.13.1 Sandwich weight 215 4.13.2 S
48、andwich bending stiffness 216 4.13.3 Sandwich bending moment capacity . 218 4.13.4 Sandwich panel buckling . 220 REFERENCES . 222 CHAPTER 5 FABRICATION OF SANDWICH STRUCTURES (MATERIALS AND PROCESSES) 1 5.1 INTRODUCTION . 1 5.2 MATERIALS 3 5.2.1 Cores 3 5.2.2 Face sheets 4 5.2.3 Adhesives . 6 5.2.4
49、Surfacing and sealing 7 5.3 PROCESSES 8 5.3.1 Core . 8 5.3.1.1 Cleaning . 8 5.3.1.2 Drying . 9 5.3.1.3 Forming . 11 5.3.1.4 Splicing . 12 5.3.1.5 Potting . 15 5.3.1.6 Septums . 15 5.3.1.7 Core stabilization for machining 16 5.3.1.8 Machining . 16 5.3.1.9 Tolerances . 18 5.3.2 Face sheets - co-cure vs. pre-cure and resin pressure . 18 5.3.3 Adhesive 21 5.3.3.1 Impression check . 21 5.3.3.2 Bonding . 23 5.3.3.3 Filleting . 25 5.4 HONEYCOMB CORE CRUSH . 28 5.4.1 Core crush during cure 28 5
