Modeling and Testing of the Sandwich Composite Manhole Cover Designed for Pedestrian Networks

This research concerning the topic, pursues the design, manufacturing, analysis and testing of the manhole cover that may be used in pedestrian networks. Although there are certain commercially available manhole covers made of glass-reinforced composites, there are a few papers published related to the modelling, simulation and mechanical testing of such parts. Herein, the manhole cover is made of the sandwich composite. The novelty of this kind of cover is to use an oriented strand board (OSB) as the core between two sides containing layers, which are reinforced with glass fibers. The OSB core leads to the increase of the stiffness-weight ratio. The paper describes the materials corresponding to the layers of the composite cover, geometry of the cover, technology used to manufacture the bending specimens and cover tested. Specimens made of materials that correspond to each layer of the cover, are tested in bending in order to determine their mechanical properties (flexural strength and flexural modulus). Bending tests and testing of the cover are also described. The composite manhole cover is also analysed by the finite element method to obtain the state of stresses and strains. The strains of the manhole cover are experimentally measured by using the tensometric method. Finally, comparing the strains with the strains experimentally measured validates the numerical simulation model.

The influence of the ageing-fatigue degradation on the mechanical properties of glass-reinforced composites

Drawing up diagnostic relations between thermal characteristics determined in thermal imaging examinations and mechanical properties, allowing for forecasting the state of material during the use, was a purpose of the work. Research was performed on polyester – glass composites which were subjected to the ageing-fatigue degradation process in a device created specifically for that purpose. It was indicated how to assess the degree of the decline, taking into account the fall in material strength properties. The basis of a method was measurement of changes in temperature in activated thermal processes. Relations between changes of the speed of heating and cooling were related to the bending strength and the modulus of elasticity. Diagnoses were backed up with microscopic examinations.

The Structural Application of Bio-Composites: A Comparison of Mechanical Properties between Bio-Composites and Glass Reinforced Composites

Green composite or bio-composite refers to a type of composite materials that consists of natural fibres and bio-polymers as its constituents. The green composite has generated great interest in research world and industries due to its advantages of renewability, biodegradability and sustainability. However due to its low mechanical properties, bio-composites has limited structural application, the area that is dominated by glass reinforced composite. As such the aim of the numerous researches on the bio-composite is to prepare green composite to have properties that can replace GRP as structural components. This paper is to compare mechanical properties of bio-composite taken from vast literature and the glass reinforced polymer composite. The properties under consideration include the tensile strength and modulus, flexural strength and modulus, elongation at break and the impact strength. It was found that with careful consideration on the chosen types of fibres and matrix, the treatment given to fibres and matrix and the manufacturing process, bio-composites can be at par or better than the glass mat thermoplastic composite.