1、Additive Manufacturing of Aerospace Composite Structures: Fabrication and ReliabilityOther SAE Books of Interest: Studies into Additive Manufacturing for In-Space Manufacturing By Rani Elhajjar and Tracy Gill (Product Code: SRP-001) Economics of Composites By George Bullen, Carrol Grant, Alan Hiken,
2、 Dan Day, e-mail: copyrightsae.org; phone: +1-724-772-4028; fax: +1-724-772-9765. Library of Congress Catalog Number 2017937319 SAE Order Number PT-181 http:/dx.doi.org/10.4271/pt-181 Information contained in this work has been obtained by SAE International from sources believed to be reliable. Howe
3、ver, neither SAE International nor its authors guarantee the accuracy or completeness of any information published herein and neither SAE International nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the u
4、nderstanding that SAE International and its authors are supplying information, but are not attempting to render engineering or other professional services. If such services are required, the assistance of an appropriate professional should be sought. ISBN-Print 978-0-7680-8405-4 ISBN-PDF 978-0-7680-
5、8406-1 ISBN-epub 978-0-7680-8408-5 ISBN-prc 978-0-7680-8407-8 To purchase bulk quantities, please contact SAE Customer Service e-mail: CustomerServicesae.org phone: +1.877.606.7323 (inside USA and Canada) +1.724.776.4970 (outside USA) fax: +1.724.776.0790 Visit the SAE Bookstore at books.sae.org 400
6、 Commonwealth Drive Warrendale, PA 15096 E-mail: CustomerServicesae.org Phone: +1.877.606.7323 (inside USA and Canada)+1.724.776.4970 (outside USA) Fax: +1.724.776.0790v Table of Contents Introduction . vii High Speed Tow Placement System for Complex Surfaces with Cut / Clamp / M. Torres Disenos Ind
7、ustriales Production Implementation of Multiple Machine, High Speed Fiber Placement for Large Structures (2010-01-1877) 7 Todd Rudberg, Rob Flynn, and Justin Nielson; Electroimpact Inc. Enhanced Robotic Automated Fiber Placement with Accurate Robot Technology and Modular Fiber Placement Head (2013-0
8、1-2290) 15 Kyle A. Jeffries, Electroimpact Inc. Composites Design Optimization for Automated Fiber Placement Process (2014-01-2261) 21 Yvan Blanchard, Coriolis Software TruPLAN Advanced Simulation for Material Kinematics Behavior during Manufacturing Layup Processes (2012-01-1856) 27 Massimiliano Mo
9、ruzzi and Dylan MacLean, Magestic Systems Incorporated; Rob Blackburn, Cytec Engineered Materials Automated In-Process Inspection System for AFP Machines (2015-01-2608) . 35 Joshua Cemenska, Todd Rudberg, and Michael Henscheid; Electroimpact Inc. Future Directions Relative to NDE of Composite Struct
10、ures (2004-01-2817) 43 Donald D. Palmer, Jr., Roger W. Engelbart, and Christopher M. Vaccaro; The Boeing Company Emerging Technologies for Use in Aerospace Bonded Assemblies (2013-01-2134) . 49 Richard J. Crossley, Svetan Ratchev, and Anthony Smith; University of Nottinghamvi The Manufacture of Adva
11、nced Composite Parts to Rigid Industrial Specifications - Can it be Made? (2013-01-2218) 59 Dennis Michael Crowley, Carwyn Ward, and Kevin Potter; University of Bristol A Status of Acceptance Criteria and Process Requirements in Advanced Composites Manufacturing, and Whether They are Fit for Purpose
12、 (2013-01-2144) 69 Dennis Michael Crowley, Carwyn Ward, and Kevin Potter; University of Bristol About the Editor 79vii Introduction Many articles have been written about the benefits of composite materials compared to traditional aluminum materials used in the aerospace industry. It is certainly tru
13、e that composites are lighter, stronger, have excellent corrosion resistance and fatigue properties and, in general, have lower costs to operate. However, those factors alone do not explain why the commercial aerospace industry did not quickly adopt composites since their widespread use in military
14、aircraft during the Cold War period. Boeing had been using small amounts of composites in commercial airplanes since the 1970s, but it would take developments in additive manufacturing of composites, and especially the advanced fiber placement processing methods, to realize the large developments se
15、en in the last few years. Before we delve into this topic, we must consider historical parallels in how the Boeing 787 (first flight in 2009) and the Airbus A350 (first flight in 2013) airplane models represent monumental shifts in material selection design by incorporating composites in large parts
16、 of the airplane fuselage and wings. Just like in the 1930s, the Boeing 247D and the Douglas DC-3 were also themselves revolutionary by introducing the semi-monocoque all-metal fuselage and cantilevered wing construction over the traditional favored wood construction. These airplanes, however, large
17、ly used the innovations in structural design of the wooden airplanes, such as the monocoque construction method (see, for example, the Loughead Aircraft Manufacturing Method of 1918). It is not the material alone that drives development or innovation, but it certainly facilitates the advancement and
18、 utilization of the material properties to the maximum extent possible. Just as the 247D and DC-3 in the 1930s marked the departure from wood to metal, today we are witnessing the departure from metal to composite in large parts of the modern commercial airliner. And just as the developments in meta
19、l technology could drive the incredible performance of airplanes from the 1930s to this day, the potential for advancements in airplanes using composites is only in its beginning stages. Ultimately, it is the development of new and efficient production methods for composites that has enabled this tr
20、ansition. In the aerospace industry, progress in automation has resulted in the development of automated fiber placement (AFP) for additive manufacturing in composite structures. AFP is closely related to automated tape laying (ATL) which is generally used for laying large amounts of composite tape
21、materials on relatively flat surfaces. AFP has seen more growth because of its ability to respond to various design requirements, such as the need to deposit short courses of material or to deposit composites on complex contours. While advanced composites have made inroads into aerospace, wind, auto
22、motive, and marine industries, only the aerospace industry has thus far been the leader in advancing additive manufacturing techniques for composites. The directional strength characteristics of composites can best be captured by using advanced automation tools to deposit the glass or carbon fibers,
23、 layer by layer, under tight tolerances for thickness, orientation, and direction. Designers are capable of modeling the structure to achieve variable strength and stiffness properties depending on the location desired. AFP results in the ability to produce large structures, such as the wing or the
24、large one-piece fuselage section used in the Boeing 787 airplane. The main advantage of the AFP technology is the ability to steer the material to address the curvature issues. It also offered the ability to optimize the design by introducing spatial variation in the stacking sequence arrangements d
25、epending on the strength and stiffness requirements. Currently, however, designs are usually made using standard quasi-isotropic stacking sequences that produce structures that are not optimized. This is done to make the design easier resulting in the common designation of these composite designs to
26、 be labeled as “black aluminum” or “black metal.” There is also a growing awareness of the need to improve quality and design by being able to predict the occurrence of defects, and to inspect and account for them effectively, thus reducing unnecessary conservatism in the designs. The use of AFP is
27、expected to continue to grow because it viii can optimize the fabrication process to allow non-traditional layups. AFP advancements in depositing prepreg tows and in-situ non- destructive evaluation (NDI) will make manufacturing high-quality, large, and complex composite structures possible. Overvie
28、w This book aims to introduce the reader to the current state of technologies involved in processing and design of polymer-reinforced fiber composites using additive manufacturings automated fiber placement methods. At both the academic and professional levels, I have been involved in the subject of
29、 design of composite structures and what to do when the structure contains defects. In my view, quality can only be appreciated if we understand and value the modern tools available to produce, inspect, and assist in the design of composite structures. Understanding these tools will allow us to desi
30、gn safer and more efficient structures in the future. Composite parts can be expensive to produce, and part of that expense comes from the difficulty to repair defects or the costs associated with scrapping parts. The chapters from seminal SAE International papers selected in this book will introduc
31、e the reader to the technology of AFP and some of the most exciting technological advancements using robotics and control. Even with the latest AFP technologies, composite structures still cannot be manufactured without the presence of many possible types of defects. For this reason, it is vital to
32、appreciate the question of manufacturability and the importance of having thoughtful discussions about acceptable process limits on these defects. While also examining the latest trends in incorporating nondestructive evaluation during the manufacturing process, the innovative design tools, such as
33、those presented, can minimize risk by predicting the location of defects before manufacturing. In a competitive environment with a variety of material choices available, minimizing time to market is as important as providing managers the ability to monitor the product through the development cycle.
34、Currently, the material layup strategy in terms of process selection and manufacturability are usually not prioritized in the design phase. Engineers do not have a good way to see how their design choices can affect the manufacturing process beyond their initial structural-level considerations. For
35、example, it is not always evident how design engineers can relate to how their design interacts with the feasibility of the stacking sequence considered, production rates, and material formability. The neglect of these factors can lead to low processing times and expensive defects in composite parts
36、. The result is typically a large amount of experimental testing necessary to qualify the materials and structures typified in the classical building-block approach. Such an environment makes mistakes difficult to solve and, should redesign be required, obtaining reliable information is hard to piec
37、e together. The ability of designers to visualize the possible defects in a virtual environment can help validate the design proposed against different manufacturing strategies. Given the need to understand the new production methods and the challenges involved in design and manufacturing, the follo
38、wing papers have been selected to introduce the reader to the question of quality in these interesting and advanced structures. In the following sections, an explanation is provided on what to expect as you go through this book. Automated Fiber Placement Composites Additive Manufacturing The first t
39、hree papers are concerned with charting the trajectory of automated fiber placement, each paper separated by a few years and written by experts in companies producing the state-of-the-art equipment in the field used by leading aerospace industries. High Speed Tow Placement System for Complex Surface
40、s discusses the unique characteristics of a carbon-fiber/epoxy tow placement system that can deposit 30-45 kg at a speed of 85 meters per minute. The paper traces early developments in the field, including similarities of the fiber placement system to old cinema heads, and how the new characteristic
41、s of the modern machine enable additive manufacturing ix of composites. Production Implementation of Multiple Machine, High Speed Fiber Placement for Large Structures describes developments for speeding the rate of manufacturing by using a cell system with multiple machines. The system can use detac
42、hable heads allowing for swapping the tow widths or changing the material type if desired. The concept of the machine reference system can be used to coordinate multiple machines for faster rates. This section is concluded with Enhanced Robotic Automated Fiber Placement with Accurate Robot Technolog
43、y and Modular Fiber Placement Head which outlines how developments in more accurate robot technologies and modular AFP heads can drive the costs down of this technology, while also improving speed, cost, and reliability. Design Optimization The realization of modern composites using AFP is a multipl
44、e-constraints problem between contradicting material, engineering, and manufacturing specifications. In Composites Design Optimization for Fiber Placement Process, an integrated systems approach for optimization of the AFP structure is presented that addresses the five constraints involved when usin
45、g AFP in the design of a composite structure. The system proposed addresses at the design stage, the constraints of material isotropy, fiber orientation, steering, gaps/ overlaps, and the manufacturing process itself. For example, computer algorithms are able to evaluate and predict fiber steering i
46、ssues, and to perhaps evaluate different material widths or to reduce the velocity of the machine in certain regions where wrinkling or tow buckling may occur. Knowing how the quality of the composite structure will turn out can allow the designers additional tools for optimization. For example, iso
47、tropy can be factored into the structural design, by mapping of the fiber centerlines to those in the finite element models used in the early design so that the properties contain the “true” material angle for each element. Similarly, the gaps or overlaps can be exported to finite element models for
48、 applying strength or stiffness reduction factors into the models for simulations performed before the manufacturing stage. In TruPLAN Advanced Simulation for Material Kinematics Behaviour during Manufacturing Layup Processes, a software application is presented to provide manufacturing analyses at
49、the conceptual design phase that makes it possible to assess the manufacturability of a composite part. The manufacturability addresses the difficulties in choosing the methods given the variables such as size, material type, and production rates desired. When using robotics and automated methods, the benefits and disadvantages of certain designs, subject to material and manufacturing constraints, are important to understand before initiating the manufacturing process. This software provides a good example of how manufacturers can reduce risks and associated costs of composite producti
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