Modelling of the strength properties of woven spatial preforms based on their structural parameters

Abstract

The aim of the study was to investigate strength formation mechanism and the development of the method for modelling the bending strength of the T-shape woven reinforced composite by means of the woven structural parameters. The T-shape reinforcements were woven and impregnated with epoxy resin by using a vacuum bagging technique to form composite. It is assumed that the determination of the impact of various woven structural parameters will allow the prediction of mechanical properties of the composite on the stage of its design. The tests were conducted using the modified three-point-bending procedure. The T-shape woven structure was manufactured with high tenacity continuousfilament PES. The results of studies were presented in the range of T-shape single and strengthened structure. Three stages of experimental work were introduced:
- the first stage was to study the impact of structural parameters of reinforcing fabrics, such as e.g. the density of the warp and weft, the number of warp threads in various parts of T-shape section, crimp of threads, on the strength properties of the composite. Reinforcing fabric was a single fabric in each T-shape section,
- the second stage of the work was to study the bending strength of the T-shaped reinforced composites, while, on the basis of the first stage conclusions, reinforcing fabric was strengthened by the laminate in the join region between web and flange,
- the third stage of the work, referring to the second one, consisted in an examination of the bending strength of the T-shaped reinforced composites, wherein the join region between web and flange in reinforcing fabric was strengthened by the monolithic multilayer structure.
The result of my research is that the evidence exists to show, that:
1. Structure "density", expressed as the density of warp and weft threads, has an impact on the strength properties of the composite.
2. The properties of the spatial composite structure depend on the join region between web and flange.
3. The level of degradation (delamination) of the composites depends on the reinforcing fabric structure parameters, such as: coefficient of filling the section with warp and weft threads, and the way of connecting web and flange.
4. In the case of composites reinforced with fabric strengthened by the laminate and monolithic multilayer structure, the element of the web and the join region between web and flange are essential for the bending strength of the composite.
5. Modification of structure of the fabric can significant by influence bending strength, and can forecast the destruction process. It is possible to program the destruction process of construction material after the limit load is exceeded.