Composite Structures: Process Analysis, Progressive Damage, Failure Analysis, and Advanced Software

compositestructures

Instructed by Anthony M. Waas, Professor of Aerospace Engineering & Richard A. Auhll Department Chair, Emeritus, at the University of Michigan, & Professor, Mechanical Engineering, AIAA, ASME, ASC and AAM Fellow. Director of SEMTE, Arizona State University from Jan 1, 2024. Founding partner of Digital Blue, a software company. 

  • This practical course taught by premier experts in Composite Aircraft Structures will cover advanced topics in composite analysis and use software from Digital Blue to demonstrate example frameworks
  • All students will receive an AIAA Certificate of Completion at the end of the course.
     

OVERVIEW
High-strength and high-stiffness carbon fiber-reinforced polymer composite laminates (CFRP) are being increasingly used for primary load bearing structures in many industries. The most common material system used is based on thermoset resins (matrix material), which come in the form of prepreg tapes allowing high flexibility and productivity using advanced automated manufacturing technologies. Engineers must be equipped with mechanism based mechanical models for the deformation response and progressive failure of these materials and structures. The mechanisms responsible for progressive damage accumulation and failure are (intralaminar) matrix cracks, which can lead to delamination initiation and spreading resulting in ultimate failure. Interlaminar fracture in CFRP, often called delamination, is defined as an out-of-plane discontinuity between two adjacent plies of a laminate. Delamination behavior has been studied by many researchers and now can be characterized in a standardized manner. Fracture properties of Mode I, Mode II, and mixed-mode (between Mode I and Mode II) delamination can be obtained from ASTM standard tests in conjunction with finite element analysis (FEA). In a CFRP structural component, the intralaminar and interlaminar modes of failure interact, therefore developing a computational model to accurately replicate the failure mechanisms and their interaction has been challenging. In this short course, the attendees will be able to learn the basic equations that given the deformation response of laminated composite structures, followed by a modeling framework that can capture the progressive damage and failure of a ply (the basic building block of laminates) when subjected to in-service loads. The manufacturing process induced residual stresses will also be discussed and the modeling that is needed to determine this initial stress (and strain) state will also be provided. Basics of the finite element modeling framework that uses a probabilistic description of the materials and a novel meshing strategy will also be presented. Elements of this framework, referred to as the enhanced semi-discrete formulation (see Ref. 1&2) will be provided. Finally, a series of experimental results that delineate the different mechanisms of failure will be presented. Based on these results, associated computational modeling and results will be presented.

Attendees will use Digital Blue (DB) software associated with the modeling framework to run several examples. The DB software works as a plug-in with the commercially available ABAQUS finite element software package. Though these commercial software products will be used in the course to illustrate example models, the course content will cover generalized principles and be applicable to all.

LEARNING OBJECTIVES
  • To understand deformation response and calculate basic laminated composite structural properties
  • To understand the thermomechanical effects incurred during the manufacturing process of tape composite laminates and textile composite laminates
  • To understand damage accumulation – mechanisms, analysis and modeling
  • To be able to characterize the mechanical properties & damage accumulation characteristics of intralaminar and interlaminar damage and failure in tape laminates
  • To understand the relation between matrix damage properties and composite damage properties
  • To understand the formulation of the finite element method and its application to computing deformation response, while incorporating damage and failure of composite laminates and textile composites
  • To understand and learn the modeling details, including novel meshing techniques for analyzing tape-based composites and textile composites
  • To understand and learn the enhanced Schapery theory and Crack band method in modeling damage and failure of composites
  • To use the Digital Blue software and interpret outcomes associated with the results obtained for example cases for tape laminates
  • To use Digital Blue software and interpret outcomes associated with results obtained for example cases for textile composites

AUDIENCE: This course is useful for engineers that deal with the design and analysis of composite aerospace structures that are made with tape-based laminated composites and textile composites. Engineers who are engaged in methods development, assessing damage tolerance and structural integrity. Basic composite materials knowledge will be helpful but is not required.

COURSE INFORMATION
Type of Course: Instructor-Led Short Course
Course Level: Fundamentals
Course Length: 2 days
AIAA CEU's available: Yes

This course is also available on-demand. Register here.

Outline

Basics:

  • Introduction to the types of aerospace composites; length scales
  • Stress-strain relationships for isotropic and transversely isotropic solids
  • Concentric cylinder model (CCM) results as a building block for tape laminates and tows in textile composites,
  • Reduction of 3D stress-strain relations to plane stress-strain relations for a lamina
  • Classical lamination theory
  • Thermal and hygrothermal stresses in lamina and laminates
  • CHILE model for curing of thermoset matrix simulation
Damage and fracture:
  • Introduction to damage and failure in composites
  • Lamina/laminate-based failure initiation theories
  • Schapery theory for a damaging lamina; obtaining Schapery parameters from tests
  • Crack band theory for post-peak response of a lamina and handling mesh objectivity
  • Basic fracture mechanics in terms of modes I, II and III for interlaminar failure
FEA:
  • Finite element method as a means to solving the 3D equations of continuum solid mechanics
  • Fiber-matrix micromechanics simulations for obtaining effective properties; periodic boundary conditions.
  • Application of the finite element method to modeling tape laminates and textile composites
  • Various aspects of FEA: Explicit/implicit, mass scaling, element types
  • Traction separation laws and their embedment in finite element applications
  • All of the topics will be supplemented by examples and when necessary, the use of software to obtain solutions to progressive damage and failure of tape laminates and textile composites.
Materials

MATERIALS

  • Attendees will use Digital Blue (DB) software associated with the modeling framework to run several examples. The DB software works as a plug-in with the commercially available ABAQUS finite element software package. Therefore, participants must have access to ABAQUS. hose who have DB licenses for the plug-in will be able to run the examples in real time. Others who have access only to ABAQUS, will be provided with the Zoom demonstration of the examples that require DB software. All participants will receive an ABAQUS .odb file of all examples for processing results.
Instructors

Anthony M. Waas

Anthony M. Waas is the Felix Pawlowski Collegiate Chair, Emeritus, in Aerospace Engineering at the University of Michigan. He is also a Professor of Mechanical Engineering, Emeritus and Adjunct Professor of Aerospace Engineering, from January 1, 2024, at the Uniersity of Michigan. Effective Jan 1, 2024 he assumed the role of Director of the School for Engineering of Matter, Transport and Energy (SEMTE) at Arizona State University. Prior to that he was the Richard A. Auhll Department Chair (2018-2023), and Boeing Egtvedt Endowed Chair Professor and Department Chair in the William E. Boeing, and Department of Aeronautics and Astronautics at the University of Washington (UW), Seattle (2015-2018). His current research interests are: robotically manufactured lightweight structures, including in-space manufactured structures, computational modeling of composite aerostructures, 3D printed lightweight structures, damage tolerance of composite structures, affordable textile composites, hydrogen storage for mobility, and data science applications in modeling of materials and structures.

Professor Waas was the Director, Composite Structures Laboratory at the University of Michigan, from 2018-2023 & 1988 to 2014, prior to joining UW in January 2015. Professor Waas is a Fellow of the American Institute of Aeronautics and Astronautics (AIAA), the American Society of Mechanical Engineering (ASME), the American Society for Composites (ASC), the American Academy of Mechanics (AAM) and the Royal Aeronautical Society, UK. He is a recipient of several best paper awards, the 2016 AIAA/ASME SDM award, the AAM Jr. Research Award, the ASC Outstanding Researcher Award, and several distinguished awards from the University of Michigan, including the Stephen S. Attwood award for Excellence in Engineering, one of the highest honors for an Engineering faculty member at the University of Michigan. He received the AIAA-ASME-ASC James H. Starnes, jr. Award, 2017, for seminal contributions to composite structures and materials, and for mentoring students and other young professionals. In 2017, Professor Waas was elected to the Washington State Academy of Sciences, and in 2018 to the European Academy of Sciences and Arts. He is the recipient of the AIAA ICME Prize, 2020, the ASME Warner T. Koiter Medal, 2020, the ASME/Boeing Structures & Materials Award, 2020, and the AIAA Dryden Lecture in Research, presented at the International Scitech Conference, 2022. Recently, Prof. Waas was elected to the US National Academy of Engineering - Aeronautics and Space Engineering Board and was awarded the CT Sun Medal, American Society of Composites, 2023.
 

Royan D’Mello, Founding Partner, Digital Blue

Dr. Royan Dmello is an Assistant Research Scientist in the Aerospace Engineering Department at the University of Michigan – Ann Arbor. He obtained his Ph. D. in Aerospace Engineering from the University of Michigan in 2014 for thesis on composite honeycomb structures for energy absorption applications. He also has a master’s in Civil Engineering (Structures) from the University of Michigan. He is currently working on modeling cure response and failure in composite pressure vessels for automotive applications and also development of fatigue modeling framework for of composite pressure vessels. He is also working on finite element failure modeling and fatigue modeling of composite textiles using progressive damage analysis methods. He was part of the team that received the American Institute of Aeronautics & Astronautics’ 2020 ICME Prize. He was a Research Associate in the William E. Boeing Department of Aeronautics & Astronautics at the University of Washington – Seattle (2015 – 2019). Apart from process modeling, he has extensive background in mechanics of energy absorbing structures (such as foams and honeycombs), stability analysis of structures as well as using micromechanics of composite materials.


Minh Hoang Nguyen, Founding Partner, Digital Blue

Dr. Minh Hoang Nguyen is currently a Postdoctoral Research Fellow at the Department of Aerospace Engineering of the University of Michigan, specifically at the Composite Structures Laboratory led by Prof. Waas. He received his BSc in Mechanical Engineering and MSc in Aeronautics from the Technical University of Berlin (TU Berlin). Dr. Nguyen completed his PhD at the University of Michigan under the supervision of Prof. Waas with the thesis titled “A novel computational framework for high-fidelity probabilistic progressive failure analysis of composite laminates”. His research interests primarily focus on fiber-reinforced polymer composites, involving both experimental and computational methods. His current projects deal with progressive damage and failure analysis via finite element methods (FEM) including probabilistic modeling and process-induced residual stresses. He led the technical development of the Digital Blue virtual testing software. Dr. Nguyen also has experience with toughened aerospace composite materials, automated fiber placement (AFP) manufacturing and studied the effects of defects. Furthermore, Dr. Nguyen is also passionate about teaching and supervising undergraduate and graduate students. He is a recipient of the ASME/Boeing Structures & Materials Award in 2020.

 

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