Influence of pretension on mechanical properties of carbon fiber in the filament winding process (original) (raw)
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Fiber-waviness Model in Filament Winding Process
Journal of Solid Mechanics and Materials Engineering, 2010
Fiber waviness is one of the initial defects in the filament winding process, and causes reduction of compressive strength of the composite structure. The mechanism of growth of fiber waviness is, however, not completely clear. In the present study, a model for generating fiber waviness is proposed. It is assumed to be due to local fiber micro-buckling arising from the compression load caused by shrinkage of a metal jig. Three faults are considered as causes of micro-buckling: bonding between metal jig and composite, insufficient cure of the resin, and initial deflection of fibers. Analysis and experiments based on this model have been carried out.
Effect of carbon fiber winding layer on torsional characteristics of filament wound composite shafts
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2018
Composite hollow shafts can be manufactured using filament winding technology employing hoop and helix winding layers. Filament winding technology offers several advantages such as continuous filaments through structure and capability for continuous manufacturing. Previous researchers have investigated composite shafts, however this research elaborates the significance of winding layer types on torsional characteristics. This paper reports the effects of carbon fiber winding layer on torsional characteristics of filament wound composite hollow shafts. Shafts were manufactured using filament winding technology with continuous carbon fiber roving and epoxy matrix material. The Finite Element (FE) simulations have been carried out with a general purpose commercial FE code, ABAQUS to demonstrate shafts in torsional loading. The results revealed that values from torsional test correlate with developed finite element model. It was concluded that helix winding layer offers high hardness and more resistance to torsional forces as compared to hoop winding layer in filament wound composite hollow shafts.
Effect of radial stress relaxation on fibre stress in filament winding of thick composites
1995
During filament winding of thick cylinders, fibre wrinkling often occurs which severely decreases compressive strength. To eliminate fibre wrinkling, appropriate processing conditions must be found. Fibre migration and stress relaxation due to resin flow are generally considered the most important factors affecting fibre buckling. Therefore, the effect of stress relaxation on fibre wrinkling during the filament winding process was investigated. To study the stress development during filament winding of thick cylinders, experiments were carried out using graphite/epoxy prepreg tows as well as dry graphite fibre. Cylinders of approximately 12 mm thickness were hoop wound on a 50.8 mm diameter aluminium mandrel. Winding tensions ranged from 13 to 34 N and winding speed was constant. A foil-type pressure sensor was applied on the mandrel to monitor the interface pressure throughout winding and storage of the cylinder. Significant stress relaxation was found to occur during winding with prepreg tow. Mandrel pressure increased over the winding of the first eight layers or so. However, between the winding of one layer and the next. mandrel pressure dropped quickly. Also, it began to decrease after reaching a maximum value. A stress relaxation analysis was carried out to determine the stress in the cylinders during winding. Several parameters were not known a priori and had to be inferred from the data. Stress distributions following winding were calculated for each case. The radial stress in prepreg wound cylinders was found to relax nearly to zero in the inner part of the tubes. Compressive circumferential stresses occurred throughout each of the cylinders. However, they reached greater magnitudes in the dry wound cylinders due to very low radial moduli. No fibre wrinkling was evident in any of the wound cylinders.
Model and experimental study of fiber motion in wet filament winding
Composites Part A: Applied Science and Manufacturing, 1998
A model for wet filament winding of thermosetting matrix cylinders was developed. The model relates the processing conditions (applied temperature, fiber tension and processing speed) to temperature, degree of cure, fiber volume fraction and stresses and strains within the composite cylinder. In this work, the modeling techniques behind predicting fiber volume fraction are described and validated. Specifically, a fiber motion model was developed which describes the motion of each layer of the cylinder during winding. This fiber motion model includes the effects of the fiber bed compacting as each new layer is wound and the resin flow through the porous fiber bed. In addition, several unique features were incorporated into the fiber motion model: fiber bed stiffness is evaluated as a function of both the fiber volume fraction and the resin cure state and a rule for the mixing of highviscosity resin with lower viscosity resin to simulate bleeding through the resin from previously wound layers. Both effects must be included if the fiber position is to be accurately predicted. Model predictions for fiber volume fraction are compared with several full-scale (1 m diameter) commercially wound cylinders. Tow tension, winding time and fiber sizing were varied. There is good agreement between model predictions and experimental data. Several important trends in both the data and model were observed: (1) low fiber volume fraction layers occur when the time between winding one layer and the next is long enough for the resin to each gelation; (2) even when the layer has not completely gelled, high-viscosity resin can bleed through to the next layer wound and Cause a low fiber volume fraction; and (3) fiber sizing can increase the overall fiber volume fraction by improving the fiber bed compaction characteristics.
Control of the pretension in filament winding process
Acta Mechanica et Automatica, 2008
A tension control system which simulates the effect of tension force in the filament winding machines has been designed and implemented in the present study. Filament Winding (FW) machines are widely used in Fiber Reinforced Plastic (FRP) composite production systems in which they have a pretensioning system to optimize the tension of the fiber during winding process. The precise control of the winding path needs highly mechatronic systems. The designed control system consists of magnetic break, servo motor, a PID control unit, a load cell and a data converter. The tension of the carbon fiber was measured by a load cell and compared to the preset value to keep the tension of the carbon fiber in predefined certain range.
Composite Structures, 2002
In this study filament winding patterns are simulated using semi-geodesic fiber path equation for an arbitrary surface. As the fiber path depends on the surface where fibers are wound, the fiber angle varies in the longitudinal and thickness directions of a pressure tank. Finite element analyses are performed considering fiber angle variation in the longitudinal and thickness directions by ABAQUS. From the stress results of pressure tanks, maximum stress criterion in the transverse direction is applied to modify material properties of failed region. At the end of each load increment, resultant layer stresses are compared with a failure criterion and the mechanical properties are reduced to 1/10 for the failed layer. Results of progressive failure analysis are compared with two experimental data. Parametric studies such as the boss to cylinder radius ratio, R b /R c , thickness, and winding angle are done to investigate their effects on the performance of pressure tanks.
Mechanical Properties of Filament Wound Pipes: Effects of Winding Angles
Quality of Life (Banja Luka) - APEIRON
The aim of this study is to investigate the mechanical properties of continuous glass fiber reinforced composite tubes produced by filament winding technique with three different winding angles. With help of split-disk tests hoop tensile properties of selected specimens were determined, where reliable results were obtained with low standard deviations. It was observed that bigger winding angle lead to higher hoop tensile properties of filament wound tubular samples. Also, the effect of reinforcement direction on the mechanical performances of these composites has been presented. Fiber fracture and fiber-matrix debonding is observed to be the dominant failure mechanisms by samples winded with bigger winding angles, whereas delamination in addition to these mechanisms is detected by samples with smaller winding angles. From received results it is concluded that, mechanical properties of composite specimens are depended from winding angles in filament winding technology.With help of co...
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The consolidation pressure and winding speed for thermoplastic filament winding were studied. Thermoplastic composite parts were manufactured from tape prepreg (APC‐2); powder‐coated, semi‐consolidated towpreg; and commingled fiber towpreg. The material used was carbon fiber (AS‐4) (60 vol%) in a PEEK matrix. The parts made were open‐ended cylinders of the three materials, 177.8‐mm ID, 228.6 mm long, 17 plies thick with a 0° lay‐up angle; and rings, 50 plies of APC‐2 thick, 6.35 mm wide (one strip wide), 177.8‐mm ID, and a lay‐up of 0°. Their quality was determined by surface finish and void percentage. The tubes made from APC‐2 appeared to have the best quality of the three prepregs. For the rings, the speed of lay‐down had a significant effect (at a 99% confidence level) on both the final width of the parts and on the percentage of voids. The pressure of the roller had a significant effect on the final widths at a 99% confidence level, but a significant effect on the percentage of...
Progressive failure analysis of low energy impact in carbon fiber filament winding cylinders
Composite material is very attractive for structural applications due to its inherent mechanical properties and low weight. The improvement in manufacture process allow composite materials be used even as primary structures in modern aircraft design such as Boeing 787 without loss of airworthiness. During service life composite structures can be damaged by collisions, dropping tools during assembly or maintenance, etc. Several impact studies were conducted for plates, but few regards curved geometries or cylinders. This study presents a progressive damage analysis of low energy impact on carbon fiber filament winding cylinders. Three different layups were used for experimental tests. A new material model based in continuum damage mechanics were implemented as a FORTRAN subroutine linked to finite element software ABAQUS for explicit dynamic analysis (VUMAT). Good correlations for force vs. time and displacement vs. time between the numerical model experimental test results were obtained.
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During the forming process of carbon fiber composite pressure vessels, the parameters of the curing and forming processes become one of the critical factors affecting the production cost and forming quality. The curing temperature of 4251 A4/B2 epoxy resin is measured in this research, and the effect of curing temperature on the mechanical properties of composite materials for winding is studied, which is finally verified in the test of pressure vessels. First, the actual curing temperature of the epoxy resin is tested and analyzed using differential scanning calorimetry (DSC). Second, under two different curing regimes, the tensile and flexural properties are tested by making pure epoxy resin matrix test pieces, Naval Ordnance Laboratory (NOL) rings, and carbon fiber composite unidirectional plates that affect the overall performance of composite pressure vessels. At the same time, the test results provide reliable process parameters for numerical simulation and manufacturing of pr...