The aim of this research was to investigate the influences of different test methods on the transverse and longitudinal deformations of specimens and the introduction of the strip quadratic method for the determination of the Poisson's ratio. The research was conducted in two parts. In the first part strip biaxial and strip quadratic methods were investigated. Based on the test results the longitudinal and transverse deformations under tensile loading in the elastic range (Hook law) were analyzed, which resulted in a proposal for modifying the test method for determining the Poisson's ratio. In the second part the Poisson's ratios for five different fabrics were determined using a strip quadratic method. The analyses of the results showed that this test method influenced the values of longitudinal and transverse deformations for the test specimen and its constituents. The proposed new method, which is based on a square-shaped specimen, assures determination of the actual values for transverse deformation during the loading.
COBISS.SI-ID: 18626838
The paper explores the relationship between subjective assessment of wearing comfort and objectively determined physiological parameters (mean skin temperature, skin relative humidity, amount excreted in sweat absorbed in clothing) in a warm environment. The experiment involved five young girls who wore two different models of women’s summer clothing (women’s dresses and women’s blouse plus shorts) made from five different raw materials, but of nearly identical structural characteristics. The investigation consisted of 450 individual tests. All wearing trial tests were performed under artificially designed ambient conditions within a computer-controlled climatic chamber. It was found that there existed a relationship between subjective assessment of wearing comfort and objectively determined physiological parameters of the test subjects. The statistical analysis results showed that coefficients of multiple linear regression in dependence of the subjective assessment of the degree of skin moisture Wskin on climatic conditions had the value of R2 = 0.87, based on physiological parameters, such as skin temperature Tskin and skin relative humidity RHskin (R2 = 0.90), and on the amount of excreted sweat Esweat and the amount of sweat absorbed within clothing Wsweat (R2 = 0.87).
COBISS.SI-ID: 20031510
The successfully solving the challenges of interdisciplinary research themes of the program requires the involvement of experts from the field of materials characterization especially from the area of electron microscopy. Electron microscopy and microchemical analysis allow visualization and analysis of textile fibres, films, and coatings on fibres. One of the advanced methods of characterization is the analysis of the double-beam electron and focused ion beam (FIB/SEM), which enables the analysis of thin films and nanoparticles on the surface of the fibres and in the cross section. For example the use of modern method SEM/FIB is described in the article; where the method SEM/FIB was used for analyse the copper surface treated with a pulsed nanosecond UV laser. Experience and knowledge will be applied to other materials in the context of a research program in the characterization of the textile materials. This work studied the effect of thin copper plate temperature on its surface morphology after irradiation using a pulsed nanosecond UV laser. The surface characteristics were investigated using scanning electronmicroscopy, energy dispersive X-ray spectroscopy, focused ion beam and stylus profilometry. When a target was at room temperature, a crater and the radial flow of molten Cu from the crater was observed. When the thin target was warm (about 360◦C ± 20◦C), a crater was smaller, and quasi-semicircular waves with the periodicity of around 3m appeared in its vicinity. The origin of the waves is Marangonieffect, causing thermocapillary waves, which in same occasions had a structure of final states of chaos in Rayleigh–Bénard convection. Experience and knowledge will be applied to other materials in the context of a research program in the characterization of the textile materials.
COBISS.SI-ID: 19470870
This paper presents research into simulating parameters effects on 3D garment drape simulations with the aim of examining influential parameters regarding the accuracies of the appearances of virtual garments. The effects on the modified appearances of 3D virtual garments due to the simulated parameters, i.e. the solver setting, soft bending and resolution were investigated. Drape simulations of fabrics and garments were analysed by using the OptiTex 3D commercial CAD system for different fabrics, of which low-stress mechanical properties were measured by using the FAST measuring system and drape parameters by a Cusic Drape Tester. A comparison between the orthogonal projections of the real and virtual fabric drapes based on the Cusic method was performed and between the appearances and dimensions of the real and 3D virtual garments. The simulation parameters observed influence drape simulations of the 3D virtual fabrics and 3D garments depending on the fabric properties and pattern piece sizes.
COBISS.SI-ID: 20113430
Woven fabrics represent unique constructions of flexible materials made from a joint bundle of fibres by interlacing them together. Their behaviour depends on structural characteristics, such as the type and properties of yarns used, yarn count, yarn twist direction, type of weave, density and contact surfaces at the areas of the interlacing points. The paper presents an effect of yarn twist direction on structural characteristics of fabrics and their particular mechanical properties. The investigation is subdivided into two parts. The first part deals with the study of contact surfaces at the areas of the interlacing points from the point of view of contact mechanics, whereas the second is focused on studying the effect of yarn twist direction on structural and mechanical characteristics of woven fabrics. The analysis of the results shows that yarn twist determines the position of the fibres on the surface. This is directly reflected in the geometries of the contact area (in the case of the Z-S twist yarns point contact occurs, in the case of the Z-Z or S-S twist yarns come into liner contact) The results show that the contact that occurs when two surfaces have the same or different yarn twist direction in contact and move relative to each other directly influences fabric behaviour when stress is applied. It was established that the stress, i.e. the force acting on the fabric, as well as the geometry and size of the contact area, generates contact compression (stress field is created in the contacts areas), causing stress at both surfaces, together with tension and deformation in the fabric. These stresses are sometimes completely elastic, but when they are high enough they can cause plastic deformations.
COBISS.SI-ID: 19888406