A heddle frame is the major part of a loom that produces woven cloth by insertion of weft yarns between warp yarns. Warp yarns are manipulated by many heddles fixed in a heddle frame.
Recently, the up and down speed of heddle frames has been increased much for productivity improvement, which induces higher inertial stresses and vibrations in the heddle frame. Conventional aluminum heddle frames have limit to the speed increase due to their low fatigue flexural strength as well as low bending stiffness. The estimated fatigue life of the aluminum heddle frame was 6 months at 600 rpm and infinite at 400 rpm, which was the same results reported by textile industries.
Carbon fiber epoxy composite materials have excellent properties for structures due to their high specific modulus (E/ρ), and high specific strength (S/ρ). They also have high damping and low thermal characteristics. Due to these benefits, box type beams made of carbon fiber epoxy composite have been widely used for light weight structures such as tennis racket, robot arms, and aircraft wing structures.
For the design of box type beams of rectangular cross-section under vertical loads, extensional stiffness matrix EA, flexural stiffness matrix EI, and torsional stiffness matrix GJ should be simultaneously considered. Also, the ratio of width to height of the cross-section, the boundary conditions at the ends of the beam, and the type and position of applied loads should be considered because the failure modes of the box beam are dependent on them.
Slender beams with narrow rectangular cross-section may buckle under bending stresses which are considerably lower than the yield or proof stresses of the materials because they have low lateral flexural and torsional rigidities. Also the slender beam under vertical loads on the top surface can be buckled in the combined twist and lateral bending modes of the cross-section, unless it has continuous lateral supports.
The sandwich construction is playing an increasingly important role in structures because of its exceptionally high flexural stiffness-to-weight ratio compared to monocoque and other architectures. As a result, sandwich construction results in lower lateral deformations, higher buckling resistance, and higher natural frequencies than do other constructions. Thus, for a given set of mechanical and environmental loads, sandwich construction often results in a lower structural weight than do other configurations.
As already described, the heddle frame is required to have smaller mass and high fatigue endurance because the accelerating mass of the heddle frame contributes the major portion of the stresses.
Therefore, in this work the carbon fiber epoxy composite materials were employed for manufacturing of the heddle frame for high-speed looms. First, in order to estimate the life of heddle frame the service load histories of the aluminum heddle frame were measured by using accelerometers. After the acceleration data were transformed into stresses, the fatigue life of the heddle frame was estimated by the rainflow counting method and the Palmgren-Miner rule. In order to determine the dimensions and stacking sequences of the composite heddle frames, the failure mode map of the composite beams were accomplished. Then, the composite heddle frames were manufactured with high strength carbon fiber epoxy composite materials. Finally, the static and dynamic properties of the aluminum and the composite heddle frames were tested and compared with each other.
