Specific heat capacity - A117
|Specific heat capacity|
|Foundational knowledge article|
Heat capacity, \(C\), is the material property representing a material’s ability to absorb heat from its external surroundings . It is the ratio of the heat that must be added to or withdrawn from a system for a resulting change in the system’s temperature . Specific heat capacity, \(c_p\), is defined as the quantity of energy required to raise the internal heat of a material one degree, per unit mass of material, without causing a phase change .
Scope[edit | edit source]
This page defines heat capacity, explains its significance in composites processing, and provides some typical values. Measurement and modelling methods are briefly discussed. Links to ASTM measurement techniques are provided, but are not discussed in great detail on this page as this is covered in CMH-17  and in the provided ASTM links.
Significance[edit | edit source]
In composites processing, the material property of specific heat capacity is involved in several thermal behaviour topics. Examples include the thermal mass of an object and the thermal diffusivity of a material.
|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|
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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.
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.