S. C. Harlock

Mechanical Characteristics of Coated Fabrics

When fabrics are coated, their deformation behaviour changes considerably. The tensile, shear, and bending properties of four typical coated fabrics have been measured using the FAST system and an Instron tensile machine. The fabrics were measured before coating, after coating and after subsequent stretching or shearing treatment. Empirical polynomial functions were fitted to the experimental load–extension curves to allow the calculation of strain energies for comparison purposes. Mechanical treatment in the form of stretching or shearing partly restored the original fabric properties and so might be beneficial in apparel applications.

A Study of the Frictional Properties of 1×1 Rib-knitted Cotton Fabrics

A new frictional constant is suggested to characterize the surface mechanical properties of 1×1 rib-knitted cotton fabrics. This study examines the influence of structural variables on the frictional properties of knitted cotton fabrics. The results indicate that both the loop length and the yarn linear density influence the fabric-on-fabric frictional properties. The variation in the structure of knitted fabrics is reflected in the frictional properties as defined by the new frictional constant. A statistical relationship is established between the frictional constant and the variables that exert some influence such as the loop length and the yarn linear density.

A 3D Loop Model for Visual Simulation of Warp-knitted Structures

As is well known, the unit element of a warp-knitted structure is the loop. It is therefore necessary to have either a physical or a geometrical description of warp-knitted loop configuration to represent it on the computer screen. In the work reported in this paper, a method was developed to obtain a three-dimensional loop model that was suitable for visual computer representation of warp-knitted structures. For this purpose, some basic two-bar structures were produced on a raschel machine, and measurements were made on photomicrographs of them to obtain a 3D configuration of yarn inside the fabrics. A general loop model based on the data obtained from the analysis of real loops in fabrics was then developed. Finally, 3D images of the basic two-bar warp-knitted structures were created on a computer by employing this proposed loop model. A CAD program was developed for this purpose. Comparison of the computer-generated images of the warp-knitted structures with their real pictures confirms that the 3D loop model developed can provide a realistic visual simulation of warp-knitted structures.

Longitudinal Wicking of Weft Knitted Fabrics: Part II: Wicking Mechanism of Knitted Fabrics Used in Undergarments for Outdoor Activities

The Washburn equation is widely regarded in wicking kinetics. However, there exists a controversy over its validity for all kinds of porous media. In strip wicking tests for the knitted fabrics assessed in this study, both a saturated zone and an unsaturated zone in vertical wicking were found, though in horizontal wicking the unsaturated zone did not significantly exist in the sample strips. Investigation showed that the value of the time exponent of the Washburn equation in horizontal wicking was around 0.5, which was in agreement with the value predicted by the equation. In vertical wicking, the Washburn equation predicted quite well the relationship between the saturated wicking length and wicking time. For the wicking length that including both the unsaturated and saturated zones, the value of the time exponent was found to be less than 0.5, so the Washburn equation was not well obeyed in vertical wicking if these zones were not differentiated from each other.

Longitudinal Wicking of Weft Knitted Fabrics: Part I: The Development of an Automatic Wicking Test Method Using Image Analysis

An automatic wicking test method using image analysis technique was developed in order to automate the longitudinal wicking test and improve the accuracy of wicking measurement. It was particularly useful for conducting wicking measurement during the initial rapid wicking process. The comparison between the manual and automatic methods proved the reliability of the developed testing method.

The Geometry of Weft-inserted Warp-knitted Fabrics Part I: Models of the Structures

This paper presents geometrical models of weft-inserted warp-knitted fabrics with tricot and chain-stitch grounds. Equations are derived relating the total run-in per course with the yarn radii, the machine gauge, and the courses per unit length in the machine state.

The Geometry of Weft-inserted Warp-knitted Fabrics Part II: Experimental Validation of the Theoretical Models

Results computed by using the equations derived in Part I are compared with experimental data for both simple and complex weft-inserted warp-knitted structures.

An Image-analysis Technique Applied to the Measurement of the Pile-fibre Distribution in Sliver-knitted Fabric

The assessment of the pile-fibre distribution in sliver-knitted fabrics has hitherto been performed subjectively and qualitatively. In order to evaluate improvements to the distribution, it would be beneficial to perform quantitative assessments. In this paper, a method is devised that uses image analysis to produce quantitatively pile-distribution factors that correlate with subjective assessments performed by individual judges.

The Geometry of Weft-inserted Warp-knitted Fabrics Part III: Production of Fabrics to Meet Finished Specifications

An important practical problem connected with warp-knitted fabrics is the determination of run-in, and/or course spacing in the machine state, necessary to produce a finished fabric to a given specification. This paper develops methods for calculating the course spacing when the finished courses and wales per unit length and the fabric mass per unit area are specified.

Computer-aided Simulation of Production in the Sewing Room of a Clothing Factory

This paper describes the application of computer-aided simulation to the sewing room of a garment-making factory. A software program has been developed that allows for any sewing room to be defined in terms of its operations, machinists, cycle times, order of operations, and amount of work in process. This can he done for either an existing production layout or a proposed layout. The production of garments can then be simulated and potential problems identified. ‘What if’ trials may be performed in order to determine the outcome of various situations or actions, e.g., a machine breakdown or parts being delayed from the cutting room or the replacement of an existing machine with a semi-automatic or fully automatic machine.