Polymeric layered composites exhibit a variety of damages following in service loading conditions, like delamination, matrix cracking or even fibre breaking. Detection of such damages and assessing their extension and severity is vital during maintenance cycle, in view of keeping the normal operational reliability. For local inspections, IR thermography and ultrasonic scanning are among the best valued NDT methods. The paper describes the inspections performed by IR active thermography, in different variants, and pulse-echo ultrasonic scanning on GFRP. A variety of layered composites and defects/damages were inspected and the results are evaluated independently, in some cases being compared each other, with valuable conclusions for the users of the mentioned NDI techniques.
The paper presents some aspects concerning the use of infrared thermography (IRT) in the evaluation of composite pipes integrity. Composite pipelines made up of glass fibres reinforced epoxy resins are increasingly used, especially in oil and gas industry, for their good mechanical properties, combined with reduced weight and excellent behaviour under hostile environment conditions. Taking into account that high reliability is required for such pipe networks, it is mandatory to choose reliable non-destructive inspection (NDI) methods to achieve efficient structural health monitoring. The main advantages of the IRT inspection are: non-contact and non-dangerous examination. In order to characterize the integrity of composites pipes, first of all the researches were interested in obtaining a set of reference images and then to examine the samples before and after the impact stress test. The conclusions point out the schemes and the optimal parameters of evaluation as well as the application limits of thermographic inspection
Composite materials are large used today in various industrial fields such as: aeronautics, military equipment, pipelines for oil transport; frequently must meet serious requirements about the quality. This paper presents the results of an experimental study on the possibilities and limits of flaws detection and measurement in composite materials by infrared thermography. In a research contract developed in our university were designed and processed samples with artificial defects in composite materials: CFRP, GRFP and Dyneema. The main aim of experimental research was to assess size of flaws positioned at different depths related to the examination area. The samples were investigated by infrared thermography and then the results were verified by different ultrasonic methods.
The mechanical and physical properties of metallic composites with aluminium matrix and alumina particles as complementary material have made them a good candidate for automotive, aerospace and many other applications. Some calculus regarding main aspect of wetting conditions between aluminium and alumina are made by using special literature information. Also, some improvement techniques of wetting conditions are described.
Abstract. The paper presents some theoretical and experimental data regarding the directional solidification, revealing the main factors (especially those which are related to the heat transfer process) which have influence on the crystals size and morphology. The crystalline structure of alloys is determined by three important factors: chemical composition, thermal conditions, and characteristics of germination and growth from liquid of solid nuclei. The solidification structure can be influenced by acting on the mould properties or directly on the cast material, both of these actions being based upon the change of temperature distribution in the alloy-mould system. Experimental data demonstrated the major influence of the thermal regime on the crystallization-solidification process, on the transcrystallization zone and they pointed out the limits to direct the crystals formation (size and shape) by changing the cooling regime.
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