Digital Image Correlation for Cement-based Materials and Structural Concrete Testing

This paper presents the application of a low-cost digital image correlation (DIC) system for automated crack mapping. The system employed makes use of a conventional digital camera, a remote image recording controller, and an open-source digital image correlation MATLAB software Ncorr. To showcase the potential of the proposed system, two case studies involving general structural and material testing were undertaken. In the first series, the DIC system was used to study the fracture processes in a reinforced concrete beam and to investigate the influence of key input parameters on the spatial quality of strain maps obtained from the DIC analysis. In the second series, the application of the DIC method was expanded to assist in the study of complex multiple micro-crack formations in ductile cement composite testing. It is shown that the strain maps obtained from the DIC technique have a close resemblance to the actual crack patterns

Comparison of Composite Laminates Machining Methods and its Influence on Process Temperature and Edge Quality

The article presents the description of technological trials and the results of three methods of machining carbon fiber reinforced composites panels. It also reviews the literature concerned heat affected zone in composites and its influence on material properties. As a part of the research, the cutting method using diamond coated saw was tested, as well as the milling method with two different types of carbide milling cutters. The processing of the panels was done using 4-axis CNC machine with special adapter for cutting discs in Composite Testing Laboratory (Center for Composite Technologies, Warsaw Institute of Aviation). The methods were compared in terms of machined edge quality and panel temperature during the processes. For this purpose, thermocouples were mounted into panels. Records from thermocouples were included. Edge quality and surface roughness have been checked by microscopic observation. Additionally, samples machined by each evaluated processing method were tested using differential scanning calorimetry (DSC). The method was used to determine the glass transition temperature of the tested material. The article conclusions contain a comparison of three processing methods in terms of cutting quality, process temperature, processing method productivity as well as DSC tests results.

Manufacturing and Testing of PAN Nano Fibres, Banana Epoxy Nanocomposite

Over past few decades composite materials, ceramics and plastics have been leading emerging materials. The applications of composite material and the area in which they are being used is growing day by day. The curiosity has gained substantially towards the use of natural fibres in composites in recent few decades. Natural fibre composites are eco-friendly and often used in engineering application such as in construction, automobile, aerospace and household applications. Nano fibres are responsible for a connection between the Nano scale and the macro scale, since their diameters are in the nanometre range and the length is continuous. Nanofibre are attracting very high interest due to their extraordinary micro and Nano structural characteristics, high porosity, mechanical strength, Flexibility and integrally large total surface area. There is increased curiosity about natural fibre based epoxy composites properties to short out engineering necessities. Hence, a matter of concern to overview and check the exiting position and put efforts for sustainable and possible commercial exploitation and additional improvements. This research work shows comparison of strengths with and without added Nano fibres to the Banana fibres composite. Testing data clearly indicates the enhancement in mechanical properties when Nano fibres are added in to Natural fibre reinforced composite..

Implementation of Automatic Sample and Composite Element Cutting Technologies

The article presents the methodology of introducing automatic carbon fiber panel cutting technologies at the Composite Testing Laboratory of the Institute of Aviation. It describes the process of implementing the new cutting technology which boosts the efficiency of preparing composite samples for strength testing, with the requirements applicable to edge smoothness and dimension tolerances taken into consideration. It also reviews the literature concerned with three most popular composite material cutting methods: laser cutting, abrasive water jet cutting and machining, presenting the strong and the weak points of each one of them. After selecting the machining technology relying on a disc, cutting tests have been performed. Cutting discs coated with diamond particles, and carbon fiber panels were used during the tests. The tests were performed with the use of the INFOTEC CNC machine, with an adapter enabling the installation of cutting discs with the maximum diameter of 150 mm.