Composites are divided into types based on fiber length. In short-fiber reinforced composites, the fiber length is about 0.3 mm. This method reduces the weight of the finished product by up to 30% and the cost of production of aerospace attachment units by up to 40% as compared to their metal counterparts, scientists from the S.P. Korolev Samara National Research University have claimed. They said that such materials could be used to create structures for various purposes: from an electric drill body to an aircraft door bracket.
The strength and stiffness of short-fiber-reinforced composites along and across the casting differ by more than a factor of two, prompting the design of lightweight and strong products to require software that allows structures’ properties to be determined depending on the organization of the manufacturing process.
According to researchers, they are currently investigating options with different proportions of reinforcing fibers, and the properties of each are being studied individually.
The method of the Samara University scientists may determine the necessary fiber content at an early stage of the products’ design. It is based on the construction of a mathematical model of the mechanical characteristics of materials with an arbitrary fiber volume fraction. The results of their study were published
in the peer-reviewed scientific journal Polymers.
"The advantage of our university's approach lies in that when we determine the parameters of the model, we take into account the third dimension — the volume fraction of fiber. This allows us to obtain a unified model of the mechanical characteristics of a line of materials and predict the properties of materials beyond the experiment,” Evgenii Kurkin, associate professor at the Samara University’s Department of Aircraft Construction and Design, said.
The scientists conducted an experimental study of the mechanical properties of short-reinforced polyamide with a volume fraction of fiber from 10 to 30% and the characteristics of the binder. They performed plate casting on a thermoplastic machine, cut samples and their tear testing on a servo-hydraulic machine, and analyzed the material microstructure using an electron microscope. Micromechanics models were used to process the results of the experiment to determine the characteristics of the composite material based on data from the properties of the fiber and the binder.
According to researchers, the industry currently uses foreign-engineered solutions. The goal of the Samara University team is to develop its own system of designing products from short-fiber-reinforced composite materials, solving the problems of casting, stiffness, and strength of the products.
The study was carried out within the framework of the Russian Science Foundation’s project
, successfully completed in June 2022. The project team plans to continue the work and develop the methods and software for the design of the products from short reinforced composite materials in the framework of another Russian Science Foundation’s project
, which started this year.