A study of ease distribution in relation to jacket pattern alteration

Abstract

Apparel industry conventionally uses empirical procedures for pattern design and prototype construction, which are time consuming and cost intensive. This research work is dedicated to upgrading the current practice of trial and error approach to engineering design. The researcher attempted to develop an Ease Distribution Model (EDM), so that pattern alteration could be implemented by inserting appropriate ease into the basic sloper at the corresponding positions according to the desired jacket style. The first step towards modeling ease distribution was the identification of ease allowance at 3D garment shape and 2D garment pattern. Segmental Girth Ease Allowance (SGEA) was newly defined in the current study to facilitate the insertion of ease into the basic sloper during pattern alteration. Owing to the limited resources and time, this study is confined to women's jacket only. Sixty-three princess-seam women' jackets were produced and their patterns were constructed by draping method according to the standard fitting criteria. Both the 3D surface data of the dress-dummy with and without different jackets were obtained by body scanner (TC2). The cross-sectional curves of different parts of the dummy body and jacket with dummy inside were generated by fitting the surface data with cubic spline equations. From the cross-sectional shape of dummy and jacket, it was divided into different portions and their corresponding SGEA were determined. By using the surface fitting approach, the function of the combinations of trigonometry functions of angle and polynomial function of girth measurement was formulated which facilitates prediction on ease distribution. The EDM with single variable of girth measurement was proposed for a given style jacket. The EDM with two variables including two girth measurements was developed to predict the SGEA of various styles. The models were verified by comparing the experimental data with the predicted data. Furthermore, the width and thickness of the cross-section were also investigated, which were related to the jacket silhouette. The effect of fabric properties on the cross-sectional shape was also investigated. The prediction can be enhanced by adding fabric bending rigidity into the model. Based on the distribution of SGEA, pattern alteration could be implemented by effectively adding SGEA into the basic sloper at the corresponding positions. Different SGEA were inserted into the bustline, waistline and hipline instead of the traditional way to add girth ease allowance to the edge of the pattern. SGEA was also added into the armhole by pivoting the bust dart and shoulder dart. Pattern alteration using the EDM was evaluated by comparing eighteen parameters of the newly produced patterns with those of the draped patterns. Fitting of the patterns was then visually assessed by three experts in garment design. This research work provided an alternative approach of pattern alteration based on Ease Distribution Model (EDM) for women's jacket. The developed models offered crucial information of ease distribution when the three-dimensional jacket style is transformed to two-dimensional jacket patterns. Although the present study is only limited to women's jacket, the original methodology can still be applied to other types of garments for future studies.