1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-03-09a71 Center Point of Contact: MSFCa71 Submitted by: Wil HarkinsSubject: Design and Manufacturing Guideline for Aerospace Composites Practice: Composites must be considered as unique materials in the design and manufacturi
2、ng process because manufacturing equipment, tooling, and inspection equipment and processes have a pronounced effect on design. Since the material is formulated while the part is being built; (1) multidisciplinary, concurrent engineering design principles and (2) careful material selection and fabri
3、cation processes must be used to obtain optimum properties in aerospace composites.Programs that Certify Usage: N/ACenter to Contact for Information: MSFCImplementation Method: This Lesson Learned is based on Reliability Guideline Number GD-ED-2205 from NASA Technical Memorandum 4322A, NASA Reliabil
4、ity Preferred Practices for Design and Test.Benefits:Conscientious adherence to proven concurrent engineering principles and careful design and material selection guidelines in the design, manufacture, and testing of aerospace composites will result in low rejection rates and high product integrity.
5、 Successful composite designs can provide design flexibility, lightweight parts, ease of fabrication and installation (generally fewer parts), corrosion resistance, impact resistance, high fatigue strength (compared to metal structures with the same dimensions), and product simplicity when compared
6、to conventional fabricated metal structures.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Implementation Method:Introduction:Composites are combinations of two or more distinct materials present as separate phases and combined to form desired struc
7、tures. They take advantage of the desirable properties of each component. The manufacturing technique used to fabricate a composite structure is dependent upon material performance requirements, structure configuration, and production rates. The composite design and manufacturing methods discussed i
8、n this guideline are primarily for structural and mechanical applications and are composed of a resin (matrix) and a fiber reinforcement. Typical reinforcements are shown on Figure 1.refer to D descriptionD Performance of composite materials in aerospace applications is superior to conventional stru
9、ctural materials such as steel and aluminum. Composite materials and their manufacturing processes can be tailored specifically to given design constraints. The superior physical properties of composites allow for design with minimum concern for dimensional stability, corrosion, and crack formation.
10、 While it is possible to tailor the properties of a composite structure to minimize problems in these areas, it is imperative that this be taken into consideration during the design process. Composite materials are significantly superior to conventional materials in strength-to-weight ratio, one of
11、the most important requirements of aerospace structures.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Design:Concurrent engineering principles (i.e., the team approach to design using designers, thermal and structural analysts, manufacturing engine
12、ers, materials process engineers, tool designers, machinists, quality engineers, quality control specialists, and reliability engineers) contribute noticeably to the success of a composite materials program. Designs of composite components which are fault tolerant to known manufacturing conditions a
13、nd variables should be selected.The success of a composite program is dependent upon establishing material properties early in the program. Establishing an accurate and reliable material property data base is one of the most important steps toward achieving a functional design. Experience indicates
14、that the basic material allowables of a specific composite product should be determined utilizing the manufacturing facilities where production will take place prior to finalizing design. The preferred process should approximate the following: (1) define environmental and performance requirements; (
15、2) review available materials against requirements to determine the family of material to be used; (3) determine materials; (4) determine materials allowables using material processed at the intended manufacturer; (5) proceed with design based on known material allowables; (6) test geometric configu
16、rations (i.e., special joints, specific contours, special ply layups, etc.); (7) along with nondestructive evaluation (NDE), use destructive evaluation to determine voids, ply dropoff, resin rich areas, etc., during initial manufacturing process development; (8) begin manufacturing production. Typic
17、al mechanical and impact damage properties of selected composites are shown in Tables 1 and 2.Table 1. Typical Mechanical Properties of Selected Composites Material Type NomenclatureTensile Strength (ksi)Modulus (Msi) Strain (%)Carbon/Epoxy Glass/Epoxy Kevlar/Epoxy Carbon/PEEK Carbon/PhenolicT300/93
18、4 IM7/8551-7 P75/934 AS4/3501-6 IM6/3501-6 E-glass/934 K-49/7934 IM7/APC-2 FM5055 245 400 135 100 330 150-170 80-85 419 15-20 20 24 44 10 23 6-8 4 24 2.6-2.8 1.0-1.2 1.62 0.2-0.5 1.0 1.5 2.75 1.85 1.6 1.0-1.2 PEEK= Polyetheretherketone Note: All samples were prepared from 16-ply quasi-isotropic layu
19、ps.Table 2. Typical Impact Damage Properties of Selected Composites (1), (4) Nomenclature Max Impact Load (lb)Energy at Max Load (ft-lb)Compression After Impact (CAI) (ksi) (2)Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IM6/3501 IM7/SP500 IM7/F39
20、00 IM7/977-2 T300/934 T650-42/1939-3 IM7/8551 IM8/8553850 1100 1080 1170 560 1010 1240 900 9.2 9.1 9.7 10.3 3.7 8.5 12.1 7.4 23.2 36.2 39.9 47.1 (3) (3) 50 (3) Notes: (1) All samples prepared from 16-ply quasi-isotropic layups. (2) CAI values are normalized to approximately 125 ft-lb impact energy p
21、er inch thickness. MSFC M for example, BJSFM is used for bearing loads, and JOINT is used for elastoplastic multiple bolt joints.Below is a list of representative commercial computer programs that are available for analyzing stresses and strains in composite materials under various conditions. The o
22、nes most often used by MSFC are indicated as: MSFC. These computer programs are available from the company or source shown in parentheses.1. ABAQUS (Hibbitt, Carlson (2) material characteristics; (3) in-process fabrication/handling/tooling effects; (4) cure process control and documentation; (5) pos
23、t cure machining.Visual inspection is used to inspect bond lines that are visible in the various bond stages and to detect any Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-visible surface discontinuities and/or delaminations. Mechanical inspection
24、 is used to verify design dimensions, acoustics, input resistance, static loads and dynamic loads. Non-destructive evaluation is perhaps the most important inspection technique for determining defects in composites, particularly the defects specified in Table 7.Table 7. NDE Techniques for Detecting
25、Defects in Composite Materials Defect/ Composite Method*X-rayUltrasonicsComputer TomographyAlcohol WipeThermographyEddy CurrentDye PenetrantDelaminations/ All 8X X X X X Density Variations/ #5X X Resin Rich-Resin Poor/All 8X X Voids/#1 X X X Crazing (Micro-cracks)/ All 8X X X Wrinkles/ All 8X X Cond
26、uctive Materials/ #2X * Composite Methods:1. Filament winding 2. Fiber placement 3. Pultrusion 4. Tape laying5. Tape wrapping 6. Press molding 7. Hand layout 8. Resin transfer moldingTechnical Rationale:MSFC experience with composites includes filament winding, tape laying, fiber placement, hand lay
27、up, computerized pultrusion, and automated tape wrapping. Computer programs are available to assist in the composite design process. The mechanical properties and impact damage properties that have been derived Provided by IHSNot for ResaleNo reproduction or networking permitted without license from
28、 IHS-,-,-from tests of various composite materials can be used by designers to select the proper material and configuration for the job. Research is continuing to expand the available storehouse of design guidelines, leading to the production of reliable aerospace composite components. Valuable refe
29、rences which provide detailed design and analysis parameters for composite materials are provided in this guideline.References:1. Agarwal, B.D., Broutman, L.J.: “Analysis and Performance of Fiber Composites,“ John Wiley and Sons, Inc., Second Edition, 1990.2. ASM International Handbook Committee: “C
30、omposite, Engineered Materials Handbook,“ Volume 1, Third Printing, August 1989.3. DOD/NASA: “Advanced Composites Design Guide,“ Volume I-IV, 1989.4. Jones, W.K.: “Test Report Graphite/Bismalemide Allowables Data Base,“ Martin Marietta Composites Technology Group, August 1987.5. Lubin: “Handbook of
31、Composite Materials,“ 1982.6. MSFC-HDBK-505A: “Structural Strength Program Requirements,“ January 1981.7. MSFC-HDBK-1453: “Fracture Control Program Requirements,“ October 1987.8. Morgan, Jr. L., Sigur, W.A.: “Fastening Techniques for Composite Materials,“ Martin Marietta Composites Technology Group,
32、 August 1985.9. NHB 8071.1: “Fracture Control Requirements for Payloads,“ September 1988.10. Sherrouse, M., Blum, C.: “Recommend Practices for Composites, Design and Analysis,“ Martin Marietta, Michoud, LA, March 1992.11. Strong, Dr. A. Brent: “Fundamentals of Composites Manufacturing; Materials; Me
33、thods, and Applications,“ Society of Manufacturing Engineers, Dearborn, MI, 1989.12. Whitney, J.M., Daniel, I.M., Pipes, R.B.: “Experimental Methods of Fiber Reinforced Composite Materials,“ SESA Monograph Number 4, Prentice-Hall, Englewood Cliffs, NJ, 1982.13. Applications of Ablative Composites in
34、 Solid Rocket Motor Nozzles Reliability Preferred Practice No. PD-ED-1218; Marshall Space Flight Center.14. Structural Laminate Composites for Space Applications Reliability Preferred Practice No. PD-ED-1217; Marshall Space Flight Center.Impact of Non-Practice: Failure to use state-of-the-art design
35、 techniques, tooling, manufacturing techniques, and automated manufacturing and inspection techniques for composite materials could result in the choice of inappropriate materials, costly scrappage, and potential failures in use. Failure to use composites in appropriate applications could result in
36、noncompetitive products with greater complexity, weight, or damage susceptibility.Related Practices: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Additional Info: Approval Info: a71 Approval Date: 2000-03-09a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
