Engineering article
Thicker does not mean proportionally stronger
How thickness affects the flex of CFRP laminate and why choosing a 5mm sheet starts with span, supports and cutouts, not just a number.
Thickness significantly increases rigidity, but does not cancel geometry
The plate resists bending not only because of the material, but also because of the distribution of the material relative to the midplane. Therefore, increasing the thickness usually greatly reduces the deflection for the same support pattern. However, the actual part is rarely a perfect continuous strip: holes, pockets, narrow bridges and loose edges change its performance. A 5 mm sheet can be rigid in a short span and not stable enough in a long cantilever. The choice should be related to the geometry of the part and the method of fastening.
Why doesn't strength increase according to a simple proportion?
An experimental study of CFRP laminates shows a pronounced thickness effect in flexural tests. When the number of layers changes, not only the cross section changes: the distribution of defects, the proportion of surface layers, and the mechanism of damage development are different. In one sample, tension of the outer layer appears earlier, in the other - compression, interlayer delamination or a local defect. Therefore, doubling the thickness cannot be mechanically translated into doubling the permissible load without calculation and data on the specific laminate.
When a sheet becomes a blank for a mechanical part
With a thickness of 5 mm, the material is often chosen not only as a cladding panel, but also as a base for a milled part. Then the result is influenced by the minimum radii of the internal contour, the depth of the pockets, the direction of the fibers at bottlenecks and the method of fastening on the machine. Removing a significant portion of the thickness locally turns the five-millimeter sheet into a thinner wall, and it is this that can determine the stiffness. It is useful for the designer to evaluate the remaining section after all machining rather than the original thickness of the blank.
What initial data provide an honest choice?
To supply sheets, please indicate format, quantity and surface requirements. For the part, attach STEP or DXF, control PDF, support diagram and main load direction. If a maximum deflection is specified, it must be reported along with the span and anchorage conditions. Check the stock section for the specific available specification; price and supply terms are confirmed with your enquiry. If a data sheet, certificate or photograph of a specific batch is required, request them separately: the document must refer to the actual material being offered, and not to the general name of carbon fiber.