抄録
In order to study sewing buttons systematically, the conditions of the wear and tear of the thread and cloth concerning buttoning were analyzed. It is considered that there are three cases : 1) Woven yarns of the fabric where the button is sewn are broken ; 2) the button thread is broken ; 3) The buttonhole is torn. The first two cases are discussed in this paper. Through the mechanical investigation on the strength of the specimen on which a button having two perforations is sewn with button thread, the following theoretical expression which shows the relation between the strength of the woven yarns and that of the button thread has been obtained :
t1 λTt/2υn×1/cosθm+B (n-1)
where λ is the number of turns of the button thread through perforations of the button and yarns of the fabric, Tl is the loop strength of the button thread, υ is the number of fabrics through which a button is sewn, n is the number of the woven yarns that is sewn by the button thread, θm is the angle between the central yarn and the farthest yarn which is inclined by sewing button, B is a constant determined by structual factors of the fabric, and t1 is the tensile strength of one woven yarn.
The expression shows that when the left side is larger than the right side, the button thread isbroken, and in the opposite case, the woven yarns are broken.
