Detecting microscopic defects in aged thermoplastic using thermoelastic technique
An experimental investigation into the thermoelastic technique applied on a thermoplastic material is presented. The TSA response in PEEK polymer after it has been exposed to methane at elevated temperatures was used to establish whether microscopic defects in the PEEK material can be detected using thermoelastic measurement. Utilising a combination of high resolution lenses and sensitivity of the detectors, the TSA method was able to detect and sizing of surface damage. The size of the defect was approximately 300 μm. However the subsurface damage was untraceable by the technique.
Introduction to thermoelastic stress analysis
The theory of thermoelastic stress analysis is reviewed and the assumptions in developing the theory are assessed. The equipment for thermoelastic stress analysis is based on infrared detection systems. The commercially available systems are described and appraised. Techniques for calibrating the output from the detectors are also provided.
A New Vacuum Pressure Infiltration CFRP Method and Preparation Experimental Study of Composite
In order to prepare a carbon-fiber-reinforced polymer composite (CFRP) with ideal microstructure and properties, a new vacuum pressure infiltration CFRP method is proposed based on an analysis of existing CFRP preparation process methods. Research on composite material preparation systems was carried out by using this new method principle. The system mainly includes a fiber pre-forming module, a vacuum heating infiltration module, a hot-press curing molding module, and a data acquisition control module. Under the conditions of natural curing at 0 MPa + 6 h + 25 °C, vacuum heating curing at –0.05 MPa + 30 min + 80 °C, and hot-press curing at 0.7 MPa + 5 min + 50 °C, a two-dimensional (2D) CFRP with excellent microstructure and properties was successfully prepared. Observing the microstructure of the prepared composite material, it can be found that the inside of the composite material was sufficiently and uniformly infiltrated, and common preparation defects such as holes and delamination were effectively controlled. Through the performance test, the bending strength of the material reached 790 MPa.