Study
Final ProductionHigh ImpactStrong effect

Porosity in Carbon/Epoxy Composites Significantly Reduces Fatigue Life

Introducing porosity into carbon/epoxy laminates through manufacturing defects drastically compromises their resistance to fatigue-induced delamination.

OhioLink ETD Center (Ohio Library and Information Network) · 2017

01

Key Findings

  • 01Porosity significantly degrades the fatigue life of carbon/epoxy laminates.
  • 02Delamination, a critical failure mode, is exacerbated by the presence of manufacturing-induced porosity.
  • 03NDE methods can effectively quantify porosity levels.
02

Application

Design takeaway

Implement stringent quality control measures during composite manufacturing to minimize porosity, and consider its impact on fatigue performance in design calculations.

How to apply

When designing with carbon fiber composites, specify acceptable porosity limits and ensure that manufacturing processes are validated to meet these standards. Utilize NDE for in-process inspection and final quality assurance.

Project actions

  • 01When fabricating composite samples, pay close attention to vacuum bagging pressure and resin infusion to minimize voids.
  • 02Explore different NDE techniques to assess the internal quality of your composite parts.
03

Method & Evidence

AimTo investigate the impact of varying levels of porosity on the fatigue interlaminar fracture behavior of carbon fiber reinforced epoxy composites.
MethodExperimental analysis and non-destructive evaluation (NDE).
ProcedureCarbon/epoxy laminate samples were fabricated using a hand layup vacuum bagging process with three different vacuum levels (0%, 50%, and 100% of full vacuum) to introduce varying degrees of porosity. The porosity content was then quantified using multiple NDE techniques, and the fatigue interlaminar fracture behavior of these samples was assessed.
ContextAerospace, automotive, and sporting goods manufacturing using carbon fiber composites.

Variables

IVPorosity level (controlled by vacuum levels during manufacturing).
DVFatigue interlaminar fracture behavior (e.g., fatigue life, delamination growth rate).
CVComposite material type (carbon/epoxy), layup sequence, curing cycle, specimen geometry, loading conditions.
04

Strengths & Limitations

Strengths

  • +Investigated a critical failure mode (delamination) in composites.
  • +Utilized multiple NDE methods for porosity assessment.

Limitations

It can be challenging to precisely control and quantify the exact amount of porosity introduced, and the fatigue testing itself can be time-consuming.

Reliability & validity

The use of multiple NDE methods increases the validity of porosity assessment. Fatigue testing, if conducted with sufficient sample numbers and controlled conditions, can provide reliable data on fracture behavior.

Think critically

How might different types of porosity (e.g., micro-voids vs. larger voids) have varying impacts on delamination resistance?

05

Design Principles

"Material integrity, particularly the absence of internal defects, is paramount for achieving predictable and reliable performance in composite structures under cyclic loading."

Understanding and controlling manufacturing defects like porosity is crucial for ensuring the long-term durability and safety of composite structures. Designers must account for the potential degradation of mechanical properties, especially under cyclic loading, to prevent premature failure in critical applications.

06

What This Means for Your Design

If there are air bubbles (porosity) inside a carbon fiber part, it will break much faster when it's bent or stressed repeatedly.

How to use in your project

  • 1.Reference this study when discussing the importance of manufacturing quality and its effect on material properties in your design project.
07

Add to My Project

08

Quick Cite

(2017). Non-destructive Evaluation Measurements and Fracture Effects in Carbon/Epoxy Laminates Containing Porosity. OhioLink ETD Center (Ohio Library and Information Network). Retrieved from https://designdex.org/study/b0944f9b-8c6d-4b62-8fb5-41826cf04f13/porosity-in-carbon-epoxy-composites-significantly-reduces-fatigue-life

Paragraph starter

The presence of porosity, a common manufacturing defect in composite materials, has been shown to significantly degrade fatigue performance by promoting delamination. This highlights the critical need for rigorous quality control during fabrication to ensure the structural integrity and longevity of composite components in demanding applications.

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Source

OhioLink ETD Center (Ohio Library and Information Network)

Non-destructive Evaluation Measurements and Fracture Effects in Carbon/Epoxy Laminates Containing Porosity

journal · 2017

View source

Questions about this research

What does the research say about porosity in carbon/epoxy composites significantly reduces fatigue life?
Implement stringent quality control measures during composite manufacturing to minimize porosity, and consider its impact on fatigue performance in design calculations. Evidence: OhioLink ETD Center (Ohio Library and Information Network) (2017).
Why does "Porosity in Carbon/Epoxy Composites Significantly Reduces Fatigue Life" matter for design?
Understanding and controlling manufacturing defects like porosity is crucial for ensuring the long-term durability and safety of composite structures. Designers must account for the potential degradation of mechanical properties, especially under cyclic loading, to prevent premature failure in critical applications.
How can designers apply this research?
Implement stringent quality control measures during composite manufacturing to minimize porosity, and consider its impact on fatigue performance in design calculations.
What were the main findings?
Porosity significantly degrades the fatigue life of carbon/epoxy laminates.. Delamination, a critical failure mode, is exacerbated by the presence of manufacturing-induced porosity.. NDE methods can effectively quantify porosity levels.
What research method was used?
Experimental analysis and non-destructive evaluation (NDE)..
How strong is the evidence?
Evidence strength is rated Strong effect, based on a 2017 journal from OhioLink ETD Center (Ohio Library and Information Network).
What should I do differently in my next project?
When designing with carbon fiber composites, specify acceptable porosity limits and ensure that manufacturing processes are validated to meet these standards. Utilize NDE for in-process inspection and final quality assurance.
What are the limitations?
The study focused on a specific composite system (carbon/epoxy) and manufacturing method (hand layup vacuum bagging). Results may vary for different material combinations or fabrication techniques.
Is there evidence that carbon epoxy affects design outcomes?
The study found that even moderate levels of porosity, introduced during the manufacturing of carbon/epoxy composites, lead to a substantial reduction in their ability to withstand repeated stress cycles before failing due to delamination. Understanding and controlling manufacturing defects like porosity is crucial for Source: OhioLink ETD Center (Ohio Library and Information Network) (2017).
Where does this porosity research apply?
Aerospace, automotive, and sporting goods manufacturing using carbon fiber composites. It sits within final production research on designdex.org.

Related research topics

carbon epoxy design research · evidence on carbon epoxy · does carbon epoxy improve design outcomes · porosity studies for designers · carbon epoxy and porosity findings · final production research evidence