Reference - Process Simulated Laminate (PSL) : A Methodology to Internal Stress Characterization in Advanced Composite Materials
| Type | Journal |
|---|---|
| Title | Process Simulated Laminate (PSL) : A Methodology to Internal Stress Characterization in Advanced Composite Materials |
| Abstract | Solidification, under nonisothermal conditions and pressure gradients present during processing, is shown to be a major contributor to the generation of internal stresses in advanced composite materials. These stresses may be amplified in composite materials with significant anisotropic characteristics. Using the process simulated lami nate (PSL) technique, a methodology was developed for the evaluation of the residual stress distributions induced during processing. The PSL contained separation films placed between certain layers of the laminate, enabling separation of the laminate after process ing. Using a strain gage attached to the laminate, the residual stress distribution over the laminate was calculated. The detached laminates served as specimens for the evaluation of through-thickness morphological and property distributions. The direct relationship be tween the residual stresses and the investigation of stress releasing phenomena such as voids, microcracks and/or fiber buckling was important for a complete evaluation of pro cess induced effects. Different techniques for residual stress evaluation were presented and compared for pressformed 40-ply unidirectional composites cooled at a rate of 20-50°C/s. A pronounced skin-core stress profile was observed in unidirectional PEEK/AS4 compos ites demonstrating compressive stresses at the surface and tensile stresses at the center of the laminate. © 1992, Sage Publications. All rights reserved. |
| Authors |
|
| Date | 1992 |
| Issue | 3 |
| Pages | 405-431 |
| Journal | Journal of Composite Materials |
| Volume | 26 |
| DOI | 10.1177/002199839202600305 |
| ISBN | 0021-9983 |
| ISSN | 1530793X |
Welcome
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 factory
- Factory cells and/or the factory layout
- Process steps (embodied in the factory process flow) consisting 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.
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:
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.
Workflows
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.
