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Porosity in Composite Materials - Part I - A336

From CKN Knowledge in Practice Centre
Perspectives - A8AIM Events - Webinars - A115Porosity in Composite Materials - Part I - A336
Porosity in Composite Materials - Part I
Perspectives article
A336 Video Thumbnail Image-qjRQafG3Ho4zCR.png
Document Type Article
Document Identifier 336
Webinar Date
  • April 26, 2023
  • Dr. Casey Keulen
  • Gavin Tao

Introduction[edit | edit source]

Defects are inherent in composite materials. They are a source of variability and often become the limiting factor of mechanical properties. Porosity is one of the most common defects found in composite materials. It can compromise the structural integrity and negatively affect aesthetics. It’s presence and extent are a direct outcome of processing parameters.

In this webinar, a comprehensive list of sources and sinks of porosity are presented and explained. Common causes of porosity are examined along with considerations for reducing or eliminating them. A number of case studies are presented to demonstrate the process of identifying the sources of porosity in a composite part.

This presentation is part of CKN’s ongoing Application + Impact (AIM) webinar series. Content discussed in the webinar is linked to the Knowledge in Practice Centre, allowing users to access this and other content in a consistent and coherent manner.

Presenter[edit | edit source]

Dr. Casey Keulen
Assistant Professor of Teaching, Department of Materials Engineering, The University of British Columbia
Director, CKN Knowledge in Practice Centre

Gavin Tao, M.A.Sc.
Research Engineer, Composites Research Network, Materials Engineering, The University of British Columbia

Webinar[edit | edit source]

Webinar slides[edit | edit source]

Webinar slides available by clicking on the icon below

PDF Icon-LK6QpdpqPx9B5d.svg

Additional information for select chapters[edit | edit source]

Chapter Chapter Title Links to related information in the Knowledge in Practice Centre
1 Welcome & introductions N/A
2 Knowledge in Practice Centre
3 Overview
4 Introduction
5 Effect of porosity on mechanical properties
6 Surface vs bulk porosity
7 The framework of sources and sinks
8 Manufacturing steps
9 Fibre/resin incompatibility
10 Entrapped gas in the setup and consumables
11 Resin over-bleeding
12 Empty space from geometry (bridging, ply drop-off)
13 Tooling dimensional error
14 Porosity in sandwich structure
15 Undissolved gases and volatiles in resin
16 Resin shrinkage
17 Lack of consolidation
18 Acknowledgement N/A
19 Summary & wrap-up N/A
20 Q&A N/A

Related pages

Page type Links
Introduction to Composites Articles
Foundational Knowledge Articles
Foundational Knowledge Method Documents
Foundational Knowledge Worked Examples
Systems Knowledge Articles
Systems Knowledge Method Documents
Systems Knowledge Worked Examples
Systems Catalogue Articles
Systems Catalogue Objects – Material
Systems Catalogue Objects – Shape
Systems Catalogue Objects – Tooling and consumables
Systems Catalogue Objects – Equipment
Practice Documents
Case Studies
Perspectives Articles

About Help
CKN KPC logo


Welcome to the CKN Knowledge in Practice Centre (KPC). The KPC is a resource for learning and applying scientific knowledge to the practice of composites manufacturing. As you navigate around the KPC, refer back to the information on this right-hand pane as a resource for understanding the intricacies of composites processing and why the KPC is laid out in the way that it is. The following video explains the KPC approach:

Understanding Composites Processing

The Knowledge in Practice Centre (KPC) is centered around a structured method of thinking about composite material manufacturing. From the top down, the heirarchy consists of:

The way that the material, shape, tooling & consumables and equipment (abbreviated as MSTE) interact with each other during a process step is critical to the outcome of the manufacturing step, and ultimately critical to the quality of the finished part. The interactions between MSTE during a process step can be numerous and complex, but the Knowledge in Practice Centre aims to make you aware of these interactions, understand how one parameter affects another, and understand how to analyze the problem using a systems based approach. Using this approach, the factory can then be developed with a complete understanding and control of all interactions.

The relationship between material, shape, tooling & consumables and equipment during a process step

Interrelationship of Function, Shape, Material & Process

Design for manufacturing is critical to ensuring the producibility of a part. Trouble arises when it is considered too late or not at all in the design process. Conversely, process design (controlling the interactions between shape, material, tooling & consumables and equipment to achieve a desired outcome) must always consider the shape and material of the part. Ashby has developed and popularized the approach linking design (function) to the choice of material and shape, which influence the process selected and vice versa, as shown below:

The relationship between function, material, shape and process

Within the Knowledge in Practice Centre the same methodology is applied but the process is more fully defined by also explicitly calling out the equipment and tooling & consumables. Note that in common usage, a process which consists of many steps can be arbitrarily defined by just one step, e.g. "spray-up". Though convenient, this can be misleading.

The relationship between function, material, shape and process consisting of Equipment and Tooling and consumables


The KPC's Practice and Case Study volumes consist of three types of workflows:

  • Development - Analyzing the interactions between MSTE in the process steps to make decisions on processing parameters and understanding how the process steps and factory cells fit within the factory.
  • Troubleshooting - Guiding you to possible causes of processing issues affecting either cost, rate or quality and directing you to the most appropriate development workflow to improve the process
  • Optimization - An expansion on the development workflows where a larger number of options are considered to achieve the best mixture of cost, rate & quality for your application.