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Derivation of the basic equations and computer solution and tabling of values of overall crimp and cover factor in terms of displacement ratio (h/D) and spacing ratio (p/D) are provided for maximum weavable constructions in plain, three-, four-, and five-harness weaves and for yarn balance (Beta) values ranging from 0.5 to 2.0.

In common with many other natural products, the nature and use patterns of items of textile clothing and equipage are such that data for formulating exact models for predicting reliability in terms of 'mission times' and 'mean-times-between failures' are not easily obtainable. However, reliability analysis based upon the probability of determining whether or not a given characteristic falls within the use requirements for the material or material system has been found feasible in many cases. A considerable amount of such data is available and is presented in the report to suggest possible approaches for reliability analysis studies. Some of the inherent problems in applying reliability analysis to a broad range of textile end items are examined and discussed.

The report contains in tabular form the solutions of the maximum weavability equations for the plain, oxfor, 3- and 4-harness twills, and 5- harness sateen in terms of warp and filling cover factors and yarn number ratio (Beta) for fabrics made from any fiber species and from blends. The tables are set up for yarn bulk densities ranging from 0.54 to 4.6; this includes fibers as light as polyethylene and as heavy as stainless steel. Supplementary tables are provided giving yarn bulk densities (assuming standard packing factors of 0.59 and 0.67) for all of the commercial fibers and for blends of the most important commercial fibers in increments of 5% ranging from 0% to 100% blend composition.

Blended yarns were produced from a good grade of cotton (1 1/2 inch American-Egyptian) and nylon 420 (1 1/2-inch - 2.3 denier) with percentages of nylon of 0, 25, 50, 75, and 100. Blending was done at the picker and at the drawframe for each blend composition. All yarns were spun to a nominal 28(s) count (cotton system) with a twist-multiplier of 3.0. Cross-sections of these yarns were examined microscopically to determine the longitudinal, radial, and rotational distributions of the fibers. It was observed that the yarns produced by picker blending were more uniform in composition than those produced by draw- frame blending. However, the draw-frame blends conformed more closely to the planned nominal composition of the yarns. The radial distribution analyses indicated that for both the picker and draw-frame blends there was in most instances a deficiency of nylon at the periphery and at the center of the yarns. However, away from the center and periphery the blend composition closely matched the average blend composition of the yarns. The rotational distribution analyses showed that sectors having a high nylon concentration were found to be flanked by sectors of slightly more than average nylon concentration, for the yarns examined., Prepared in cooperation with Lowell Technological Inst., Mass.

The report contains in tabular form the solutions of the maximum weavability equations for the plain, oxford, 3- and 4-harness twills, and 5- harness sateen in terms of warp and filling cover factors and yarn number ratio (Beta) for fabrics made from any fiber species and from blends. The tables are set up for yarn bulk densities ranging from 0.54 to 4.6; this includes fibers as light as polyethylene and as heavy as stainless steel. Supplementary tables are provided giving yarn bulk densities (assuming a standard packing coefficient of 0.59) for all of the commercial fibers and for blends of the most important commercial fibers in increments of 5% ranging from 5% to 95% blend composition.

Investigations on the wear of cotton fabrics were conducted by the U. S. Army Natick Laboratories. It was found that the theories of 'adhesive' and 'abrasive' wear, originally developed for metals, when applied to textile wear problems, provide new insights into the interpretation of laboratory and field measures of wear resistance. The predominant form of wear of military clothing is of the 'abrasive' type. This finding stimulated the development of two instruments which provide essentially the abrasive type of wear. These two instruments are described. Early studies made by the Army on the influence of garment fabric weave and weave orientation both in field and laboratory wear were extended to determine their influence on the wear that occurs in laundering. With the increase use of resin treatments to produce desired functional properties in military fabrics, this type of wear has become more important because of the sensitivity of resin-treated fabrics to laundering damage. It was found that the location and rate of edge wear in seams is a function of weave type and fabric orientation.

This report is a survey of recent work on the wear resistance of military textiles. It summarizes studies made on test methods and wear mechanisms, and includes the results of some practical wear trials. Two new instruments are described. One measures the snagging resistance of textiles and the other measures an 'abrasive' type of wear action which appears to correlate with combat usage. Wear trials on cotton, wool, and blended fabrics are described and the status of correlation studies of laboratory and field wear are reviewed.

An analysis was made of 20 nylon mountain climbing ropes which had been in use for periods up to 18 years, to discover the extent and cause of deterioration in strength and energy-absorbing ability and changes in hardness and stiffness. It was found that loss in strength and energy-absorbing ability arise primarily from fiber abrasion which occurs at the surface of the rope. The nature of the rope construction is such that surface abrasion affects each of the three strands of the rope and all of the yarns in each strand except the few which constitute the so called 'inner-core.' There is no evidence that sunlight damage occurred to any significant extent in these ropes. The amount of abrasion, and loss of strength were directly related to the amount of use (not age), for those ropes that had more quantitative use histories. A Use Index (computed from the number of days of use) may be used to estimate rope deterioration. The extent of hardening and stiffening of the ropes was found to vary over a wide spectrum, but the causal factors were not determined., Prepared in cooperation with Boston Naval Shipyard. Materials Lab.

Studies were made of the effect or structural variables on the felting shrinkage of woven wool fabrics. Factors analyzed such as yarn count and texture revealed the importance of tightening the fabric structure as a means of reducing potential laundering shrinkage. Use of the "cover factor" computation, as defined by Peirce, provided a useful measure of the tightness of structure which could be correlated with shrinkage. Other measures of the tightness of fabric structure, such as air permeability and fabric rigidity, were also useful in predicting the potential shrinkage of these fabrics. Other structural parameters studied were yarn twist and weave. Yarn twist was found to have a significant effect on felting shrinkage and plain woven fabrics showed greater felting resistance than various twill weaves of similar texture.

A summary is given of the success achieved in the Quartermaster Corps' educational procurement of shrink-resistant shirting. This small-scale run, participated in by many finishers and producers of shrink-resistant compounds, proved the feasibility of treating this particular fabric for shrink resistance and also afforded contractors an advance opportunity to learn by actual experience the production problems involved. The report emphasizes the difficulties encountered, especially as to stiffness, aging, shade, and colorfastness. The results show the quality level met by each contractor (represented by code designation) for each pertinent characteristic.

The abrasion resistance of 15 prototype fabrics representing single fiber constructions and blends of 12 different fibers is measured. The purpose of evaluating this group of fabrics was to obtain a pattern of performance which may be relatable to inherent properties such as work-to-rupture, melting point, and friction. The report presents an interesting by-product of the study, which demonstrates the relatedness of some laboratory instruments for evaluating wear.

New evaluation techniques and new units of measurement have become available in recent years to characterize comfort factors in clothing design. A brief review is presented of some of the latest work in these areas with a view to stimulating interest on the part of the clothing designer and textile technologist in making greater use of the new methodology.