This paper presents a study of the possibilities of evaluating thermal parameters of single and multilayer structures using dynamic thermography. It also discusses potential uses of lock-in thermography. It presents a simulation of a periodic excitation of a multilayer composite material. In practice, the described methods can be employed in various applications, for example, in multilayer nonwoven microelectronic components manufactured from hemp fibers, chemical fibers, with an addition of electrically conducting fibers, and in medicine and biology. This paper describes tests conducted with lock-in thermography on carbon fibre reinforced composites with implanted delamination defects. Lock-in thermography is a versatile tool for non-destructive evaluation (NDE). Lock-in thermography is a fast, remote and non-destructive procedure. Hence, it has been used to detect delaminations in the composite structure of aircraft. This method directly contributes to an improvement in safety.
One of the objectives of the European SUBZERO project was to study the influence of sweat evaporation and condensation on the heat transmission properties of cold protective clothing. With the sweating thermal manikin Coppelius, water vapour transfer through and water condensation in the clothing can be determined simultaneously with the thermal insulation. In this study, 4 cold protective ensembles, intended for use temperatures between 0 and -50 °C, were measured with the dry manikin and at 2 different sweating rates. In addition, the ensembles were measured with non-sweating thermal manikins and in wear trials.
The purpose of this research was to develop practical care procedures to help maintain the protective quality of flame resistant workwear laundered by workers in the field. Based on observed field conditions, experiments were conducted that simulated domestic laundry procedures. The first experiment involved two flame resistant (FR) fabrics, contaminated or not contaminated with oil. Independent variables also included detergent type and laundry pre-treatment. Other laundry parameters were controlled. Results indicated that it is easier to maintain the FR performance of the FR-treated blend than it is for the aramid fabric. It is hypothesized that energy generated by initial ignition of oil on the specimens triggers the FR mechanism of the treatment, which in turn inhibits further combustion. A second experiment using larger specimens and a domestic washing machine also supported the hypothesized mechanism.
The aim of this study was to analyse the transfer of steam through different types of textile layers as a function of sample parameters such as thickness and permeability. In order to simulate the human body, a cylinder releasing defined amounts of moisture was also used. The influence of sweating on heat and mass transfer was assessed. The results show that in general impermeable materials offer better protection against hot steam than semi-permeable ones. The transfer of steam depended on the water vapour permeability of the samples, but also on their thermal insulation and their thickness. Increasing the thickness of the samples with a spacer gave a larger increase in protection with the impermeable samples compared to semi-permeable materials. Measurements with pre-wetted samples showed a reduction in steam protection in any case. On the other hand, the measurements with a sweating cylinder showed a beneficial effect of sweating.
Penetration of liquid pesticides through textile materials is a criterion for determining the performance of protective clothing used by pesticide handlers. The pipette method is frequently used to apply liquid pesticides onto textile materials to measure penetration. Typically, analytical techniques such as gas chromatography (GC) are used to measure percentage penetration. These techniques are labor intensive and costly. A simpler gravimetric method was developed, and tests were conducted to compare the gravimetric and GC methods of analysis. Three types of pesticide formulations and 4 fabrics were used for the study. Diluted pesticide formulations were pipetted onto the test specimens and percentage penetration was measured using the 2 methods. For homogeneous formulation, the results of the 2 methods were fairly comparable. However, due to the filtering action of the textile materials, there were differences in the percentage penetration between the 2 methods for formulations that were not homogeneous.
The purpose of protective clothing and other personal protective equipment (PPE) is to provide escape time, to reduce the burn injury level, and to prevent aggravation of the consequences to workers during exposure to an electric arc. In this study the flammability properties of 12 different types of flame-retardant fabrics were compared with the normally used flame spread test method (EN 532:1994) and electric arc test method (ENV 50354:2001). In the arc test at the lower testing current level of 4 kA, the requirement was passed by materials which did not pass the flame spread test. These materials contained a large amount of melting fibres, and therefore tended to shrink or melt. In order to meet the current level of 7 kA, a rather thick and heavy flame-retardant fabric is needed to pass the requirement. Lighter fabrics tended to break open in the tests. The flame retardancy of the under layer fabric is therefore important to ensure the needed protection.
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