Theoretical and experimental study of braid pattern in mandrels with arbitrary cross-sections

Abstract

Braid angle is a key factor associated with the mechanical properties of braided composites, so accurate prediction of this angle is of vital importance for the design and manufacture of braided preforms. This paper presents a theoretical model for the prediction of braid angle at any point of a mandrel with constant arbitrary cross-section by taking into account the kinematic parameters of circular braiding machine. The proposed theoretical model pays particular attention to two parameters that strongly affect the braid angle, namely the position of fell point on the mandrel’s surface and the yarn length between this point and the carrier. Both of these parameters undergo continuous change during braiding and thus should be calculated on a point-to-point basis. The model was validated by a series of braiding experiments conducted, using a circular braiding machine, on mandrels with circular, elliptical, and oval cross-sections and then determining the resulting braid angles over the mandrel’s surface by an image processing method. The experimental results showed the high accuracy of the proposed theoretical model in predicting the braid angle for mandrels with constant arbitrary cross-section. Thus, the proposed model can contribute to faster and more accurate design and manufacture of braided composite preforms.

Engineering hybrid textile braids for tendon and ligament repair application

“…The braid angle, defined as the angle formed by the intertwining yarn with the braid axis, varies with parameters such as yarn thickness, braiding machine speed (related to the movement of the yarn carriers), and take-up speed, 53,55 and strongly influences the mechanical behavior of braided structures. 57 The braid diameter is modulated by variables such as the number of yarns, braiding angle, number of fiber intersections per unit length of the yarns, and linear density (tex). 56 Since all the braids were produced under similar processing conditions, specifically the same take-up rate, the major factor that could lead to variations in the braiding angle and braid diameter was the yarn type.…”

Robot trajectory optimization control of braiding for three-dimensional complex preforms

“…Fouladi et al 12 proposed to braid the flat mandrel with elliptical guide ring, and established a theoretical system for this method. Hajrasouliha et al 13 proposed a model to predict the braiding angle on any constant cross section. The braiding model proposed by Kessels and Akkerman 14 is suitable for the prediction of yarn trajectory on the mandrel with asymmetric cross-section changing along the center line.…”

Modeling method of irregular cross section annular axis braided preform based on finite element simulation

“…Whether it is the simulation model or the actual braided preform, braiding angle and yarn spacing can be measured by image analysis software. 21 As shown in Figure 2, area 1 represents the area of the mandrel surface from point A to B, area 2 represents the area from point B to C, and area 3 represents the area from point C to A. According to the area division of the mandrel surface in Figure 2, images of the simulation model and the actual braided preform in these areas are obtained.…”