[Article]: The most common mistakes in designing composite reinforcements

Designing elements made of mixed materials is a complex process that requires a precise understanding of both the material’s properties and the conditions in which it will operate. Even small errors in the design phase can reduce the durability of the structure, affect its performance, and in extreme cases lead to failure. It is worth taking a closer look at the mistakes that appear most often when developing projects based on this type of solution.

Improper selection of geometry and fibre orientation

One of the most common mistakes in designing composite reinforcements is mismatching the fibre layout with the direction of the applied loads. In these materials, fibres act as load-bearing components and determine the strength of the structure. When their orientation is random or inconsistent with the direction of forces, local weaknesses and stress concentrations occur.
Equally important is the selection of layer thickness and shape. Too few layers lead to excessive deformation, while too many may result in unnecessary weight and increased cost.

Omitting environmental factors

Designers often overlook the fact that composite reinforcements must withstand environmental influences such as moisture, UV radiation or temperature fluctuations. Failing to consider these aspects during the design stage leads to gradual material degradation, especially in polymer-resin structures.
Long-term water exposure can alter mechanical properties, while UV radiation causes brittleness and loss of cohesion between fibres and the matrix. When designing a structure, it is necessary to consider not only mechanical loads but also the operating environment.

Incorrect numerical modelling and oversimplified calculations

Another common issue is the use of excessive simplifications in numerical analyses. Computer models should accurately reflect the real behaviour of structures, yet aspects such as material anisotropy or interlayer interactions are often disregarded. As a result, the calculations fail to represent actual stresses, which may lead to faulty design decisions.

In the case of composite reinforcements, it is particularly important to use appropriate material models that account for directional stiffness and strength.

Lack of quality control and insufficient supervision over production

Even the best-designed composite reinforcements can fail if the production process is not properly controlled. Incorrect layer placement, air pockets, contamination or improper curing conditions all contribute to structural defects. Every stage—from mould preparation to final inspection - should be strictly supervised. The absence of quality-control procedures often undermines the entire effort put into the design and calculations.

How to avoid errors and design with full awareness?

Although errors in designing complex structures cannot be completely avoided, they can be significantly reduced. The key is an interdisciplinary approach: cooperation between the designer, technologist and material specialist makes it possible to identify potential issues already at the concept stage. It is also worthwhile to invest in prototype testing and numerical validation. This allows composite reinforcements to achieve maximum durability and efficiency.