A composite laminate is a laminate material which has multiple different layers. Determine minimum bend radius in composite laminates with help from an applied physics professional in this free video clip.

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A composite laminate is a laminate material which has multiple different layers. Determine minimum bend radius in composite laminates with help from an applied physics professional in this free video clip.

Part of the Video Series: Such Great Physics

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Hello, my name is Walter Unglaub. And this is how to determine minimum bend radius in composite laminates. A composite laminate is a laminate material which has multiple different layers. These different layers can have different physical properties with different types of stresses and strains. So, if we try to bend this composite laminate, which will typically two or three at least different material layers. We have to understand that the bending isn't necessarily arbitrary. As we bend the material, parts of it on the outer end will stretch where as components inside will bend inwards and shrink. So, there are multiple properties that we have to identify. One is the thickness, T, another is the distance from the inner wall or inner side of the composite laminate to what we call the neutral line. So this distance right here can be denoted by lower T and the neutral line represents the part of the space inside of the composite laminate. Where all the internal forces cancel out. So there are no internal forces here. Finally we have to understand the composite laminate will have what's called a K factor. So this K factor represents a neutral access offset. And the K factor can formulated in terms of this distance, lower case T and the total thickness of your composite laminate. So, we can define the K factor as lower case T divided by capital T. Now, we can use the equation for the bend allowance. The bend allowance is given by L is equal to A times capital R plus KT. L is the bend allowance, A is the angle. So, if we draw a circle, this is the angle A and this would be R, our minimum bend radius. Now, if we solve for R, which is what we're interested in, we end up with R is equal to L over A minus KT. And if we substitute in our definition for the K factor, then we end up with R is equal to L minus A, little T over big T. So, the thickness cancels out, all over A. So we have a simplified expression. We have the bend allowance minus the angle for which we can draw a circle in the part of the laminate that bends. Times this distance to the neutral line divided by our angle again. An angle can be measured in either in radiance or degrees. But if you want to switch from radiance to degrees, you have to use the conversion factor, 180 over Pi. my name is Walter Unglaub. And this is how to determine minimum bend radius in composite laminates.