Nowadays, composite materials are becoming more and more popular. One of the primary composite materials for modern structures is glass fiber reinforced plastic (GFRP), which is commonly used in aviation, modern transport, wind power plants, etc. Scientists of South Ural State University carried out extensive studies in order to research ballistic properties of this composite material, which is to allow improving the efficiency of its use in the future.
Strength test
Glass fiber reinforced plastic (GFRP) is a popular material due to the fact that it is comparatively cheap while possessing high strength. Many papers are dedicated to research of this material’s properties. However, practically all well-known results regarding ballistic characteristics of glass fiber reinforced plastic do not take into account various loads occurring when operating the structures, or consider comparatively low impact loading speeds. At the same time, the more important and frequently encountered problem is an impact at a high speed. The team of scientists from SUSU’s Institute of Engineering and Technology managed to determine ballistic characteristics of glass fiber reinforced plastic under its exposure to operational loads at a high speed of impact loading.
“It is often that nozes of modern trains, which are produced out of composite materials, are exposed to impacts during the train’s movement. We have set the task to study the influence of the impact force on a plate made of composite material under the normal operational load. We stretched the sample. i.e. created a strained condition, and then we performed an impact and determined its ballistic properties,” says one of the project authors, Mikhail Zhikharev.
A compact acceleration test bench was used for studying the ballistic properties. During the experiment, a ballistic stand was placed inside the testing machine which helped performing stretching of the sample till the given value of preliminary load. Speed of the projectile varied from 100 till 800 m/s for each level of loading.
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Experiments for upcoming research
In order to receive the full picture of properties of the composite glass fiber reinforced plastic, a simulation was carried out using the method of finite elements of preloaded plates made of glass fiber reinforced plastic and exposed to a ballistic impact using the ANSYS Workbench package. At that, results of numerical modeling were sufficiently close to the data obtained in the course of the real experiment.
“We determined dependencies of ballistic limit value on the value of preload,” explains Mikhail Zhikharev. “This is how we determined that the ballistic limit of a plate made of glass fiber reinforced plastic reduces for 15% under loading up to 50% from the ultimate strength limit. Provided taking into account the obtained data, modern trains and trams made of glass fiber reinforced plastic are going to be designed as more resistant to operational loads. This will increase their reliability and service life.”
The work on researching the properties of glass fiber reinforced plastic was carried out by scientists from South Ural State University in the frameworks of a grant by the Russian Science Foundation. The obtained results have been published in Composites Part B: Engineering high-rank scientific journal, which is included in Scopus (Q1) citation database. The obtained technique on research of properties of materials is to be used when designing new composite materials, which are planned to be created at SUSU.