2D AND 3D PROCESSING OF THE INTERDEPENDENCE BETWEEN THE COMFORT MAIN INDICATORS

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1 BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI Publicat de Universitatea Tehnică Gheorghe Asachi din Iaşi Tomul LVII (LXI), Fasc. 1, 2011 SecŃia TEXTILE. PIELĂRIE 2D AND 3D PROCESSING OF THE INTERDEPENDENCE BETWEEN THE COMFORT MAIN INDICATORS BY IONUł DULGHERIU, CRISTIAN-CONSTANTIN MATENCIUC, NICOLETA CIUHAT and STAN MITU Gheorghe Asachi Technical University of Iaşi, Faculty of Textiles & Leather Engineering and Industrial Management Received: November 3, 2010 Accepted for publication: December 10, 2010 Abstract. In many cases it is necessary to establish some statistical correlations between two or three variables that are experimentally determined. These correlations are identified by means of the statistical processing of a great number of measurements, the traditional methods of calculus involving a considerable workload. When determining the comfort and the function of the clothing items, a special importance is placed upon the establishment of relationships between the defining parameters and the characteristics of structure of the plane surfaces from the ensemble, their correlation as well as the manner in which some of the textile and physical features condition some of the interdependences. The values of the physical characteristics that are to be processed are generally obtained following their measurement or their calculation and the comparison, if the case may be, with another measure of the same type taken as a reference unit. In the present paper the authors calculated two sets of experimental data regarding textile and physical characteristics used to determine the main comfort indicators in the case of garments intended for men for the cold season that include a coat and a raincoat. The paper also presents the interdependence equations as well as the correlation coefficients determined for the experimental data. Key words: garment, comfort, thermal insulation, vapour permeability, resistance to air passage, air permeability, data processing. Corresponding author; idulgheriu@tex.tuiasi.ro

2 32 IonuŃ Dulgheriu et al. 1. Introduction When determining the comfort and the function of clothing items, a special importance is played by the relations between the defining parameters and the structure characteristics of the plain surfaces of the ensemble, their correlation as well as the way some of the textile physical features condition some of these interdependencies (Mitu, 2000). The paper studies this interdependence considering a multitude of clothing layers, types and ensembles. The garments are intended for the halfseason for men and include coat and raincoat. The structural variants and their interaction with the environment are illustrated in Fig. 1. Two structural variants were considered for the study, based on the assembly technology used: classic sewing and heat welding. Fig. 1 Structure of the garments Two sets of data were calculated pertaining to the textile and physical features. These are useful when establishing the main indicators of comfort influencing the studied clothing structures. In conformity with the known methodology (Mitu, 2000), the clothing structures for which the comfort parameters were determined are obtained using two technological variants, namely: classic technologies and thermal pressing technologies, in both cases the choice being an appropriate base fabric. This specification must be made because many variants contain new fabrics based on micro fibres or adequate blends (Mitu & Mitu, 2005).

3 Bul. Inst. Polit. Iaşi, t. LVII (LXI), f. 1, The following comfort characteristics were taken into consideration: R vmed the resistance to vapour passage under normal conditions; R sumlab the total thermal resistance under laboratory conditions; R summed the total thermal resistance under normal conditions; R p the resistance to air passage; P a the air permeability. The calculi were done both under normal and laboratory conditions, which provided a wide field of investigation and allowed the introduction of comparison elements. As a rule, the functional dependence of a variable y on another variable x can be empirically studied, in an experimental manner, performing a series of measurements on the variable y for different values of the variable x. In the current case, the results correspond also to the point cloud from the representations. The problem that arises in this case is to find an equation that models the comfort behaviour of the garments, based on the experimental data. The input variables are the air permeability and thickness, while the output variables are given by the thermal resistances of the ensembles. 2. Experimental Work and Interpretations The results of the experimental research lay at the basis of the estimation of the interdependence mathematical models as accurate as possible (Person, 1997). Fig. 2 Air permeability in relation to thickness. With regards to the interdependence between air permeability and thickness, as Fig. 2 reveals, there is a linear interdependence between these

4 34 IonuŃ Dulgheriu et al. parameters and the correlation coefficients are close to 0.85 in both cases. The orientation of the regression straight lines highlights a reduction in the air permeability in relation to thickness while by testing the equality with the average values the two equation terms are identical. From the Figs. 3 and 4 results the variation of the thermal resistance with thickness, for both testing conditions (laboratory and normal environment), as well as for both types of garment technologies. In all the situations, the thermal resistance varies within reasonable limits specific to the season, that is m 2.h.ºC/ kcal, while the thickness varies between mm. The resistance to vapour permeability also increases in relation to thickness for the variants made using both technologies and the limits are between mm.h.m 2 /g. This variation is shown in Fig. 5. Fig. 6 illustrates the variation of the resistance to air passage in relation to thickness. If the resistance to air passage varies between mm.h.m 2 /kg, the limits for the ensemble thickness remain the same, that is mm. Fig. 3 Thermal resistance in relation to thickness, first variant. Fig. 4 Thermal resistance in relation to thickness, second variant.

5 Bul. Inst. Polit. Iaşi, t. LVII (LXI), f. 1, Fig. 5 Resistance to vapour passage in relation to thickness. Fig. 6 Resistance to air passage in relation to thickness. Fig. 7 presents the variation of the resistance to vapour passage with thickness This can be explained from a physical point of view by defining the notion of resistance to vapour passage. When considering the body clothing environment relation, this variation shows that when the air flow increases the body discharges a smaller quantity of humidity, decreasing thus the resistance to vapour passage within small interval. Figs. 8 and 9 present the relation between the thermal resistance and the thickness There is an increase in relation to the thickness and a variation within very strict limits in relation to air permeability that also varies within very narrow limits. One can remark (Fig. 10) an obvious interdependence between the thermal resistance, the resistance to vapour passage and the resistance to air

6 36 IonuŃ Dulgheriu et al. passage. Thus, if the thermal resistance is high, the values for the resistance to vapour and air passage are also increasing. In Fig. 11, one can observe the way in which the resistance to vapour permeability increases at thickness increase, remaining in almost constant limits in relation to air permeability, which for the clothing structures under analysis is maintained within very narrow limits. The total thermal resistance calculated under laboratory conditions also increases in relation to thickness and decreases when air permeability increases. The 3D representation system highlights this (Fig. 12). The same evolution of the total thermal resistance is evident for normal environmental conditions, noticing an obvious increase in relation to the thickness and a decrease in relation to air permeability (Fig. 13). In Fig. 14 it is represented the complex function that expresses the interdependence between the resistance to air passage and air permeability, increasing according to the thickness and decreasing with air permeability. The thermal resistance calculated for normal environmental conditions (Fig. 15), increases in relation to the resistance to vapour passage calculated under the same conditions, having the same evolution in relation to the resistance to air passage. Fig. 7 Variation of the resistance to vapour passage with thickness

7 Bul. Inst. Polit. Iaşi, t. LVII (LXI), f. 1, Fig. 8 Variation of the resistance to vapour passage with thickness Fig. 9 Variation of the resistance to vapour passage with thickness

8 38 IonuŃ Dulgheriu et al. Fig. 10 Variation of resistance to air passage with thickness Fig. 11 Variation of the thermal resistance with resistance to vapour and air passage.

9 Bul. Inst. Polit. Iaşi, t. LVII (LXI), f. 1, Fig. 12 Variation of resistance of air passage with resistance air passage and thickness. Fig. 13 Variation of the resistance to vapour passage with thickness

10 40 IonuŃ Dulgheriu et al. Fig. 14 Variation of resistance to air passage with thickness Fig. 15 Variation of the thermal resistance with resistance to vapour and air passage.

11 Bul. Inst. Polit. Iaşi, t. LVII (LXI), f. 1, Conclusions The paper studies the interdependence between thermal comfort characteristics for male garments intended for the intermediate season that include rain coat and coat. The two structural variants were tested to determine comfort properties related to thermal resistances based on air and vapour permeability. The graphical interpretation of the experimental data shows the way that the input variables (air and vapour permeability) influences the thermal behaviour of the garment ensembles. This interdependence was also characterised by the regression equations. REFERENCES Mitu S., Confortul şi funcńiile îmbrăcămintei. Edit. Gh. Asachi, Iaşi (2000). Mitu S., Mitu M., Bazele tehnologiei confecńiilor textile. Edit. Performantica, Iaşi (2005). Person R., Utilizare Excel (Manual de utilizare complet). Edit. Teora, Bucureşti (1997). INTERPRETĂRI 2D ŞI 3D ALE INTERDEPENDENłEI DINTRE PRINCIPALII INDICATORI DE CONFORT (Rezumat) În multe cazuri este necesară stabilirea unor corelańii statistice între două sau trei mărimi determinate experimental. Aceste corelańii se determină prin prelucrarea statistică a unui număr mare de măsurători, metodele clasice de calcul presupunând, un volum de muncă considerabil. La determinarea confortului şi funcńiei îmbrăcămintei, o importanńă deosebită o are stabilirea legăturilor dintre parametrii de definire şi caracteristicile de structură ale suprafeńelor plane din ansamblu, corelarea lor, precum şi modul în care o serie dintre caracteristicile textil fizice condińionează unele dintre interdependenńe. Valorile numerice ale mărimilor fizice ce urmează a fi prelucrate se obńin în general ca rezultat al măsurării sau calculării acestora şi compararea, dacă este posibil cu o altă mărime de acelaşi gen luată ca unitate. În lucrarea de fańă au fost calculate două seturi de date obńinute în baza unui număr foarte mare de determinări aferente caracteristicilor textil-fizice utile în stabilirea indicatorilor principali de influenńă a confortului pentru structuri vestimentare specifice semisezonului, destinate bărbańilor, ce conńin sacou şi impermeabil. Indiferent că este vorba de reprezentarea în sistemul 2D sau 3D, în fiecare figură se înscrie şi ecuańia de interdependenńă, cât şi coeficientul de corelańie.