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An account is given of an investigation of the effects of fibre type (rayon, acrylic fibre, wool, and cotton) and dimensions on the properties of needled fabrics, the test methods used being those described in a previous paper. Some fabrics show a stick-slip behaviour in extension; others deform smoothly. Rayon webs — consolidate more easily on needling than Courtelle or wool webs. Longer fibres give higher fabric strengths. Finer fibres also give higher strength, unless fibre damage occurs. The influence of fibre friction is discussed. [ABSTRACT FROM AUTHOR]

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One of the most important process parameters in making compound products is the expansion of the bonding surface. Bonding is not obtained until a critical surface expansion, characteristic of the deformation process, is reached. This paper deals with an experimental investigation of the influence of a superimposed hydrostatic pressure on the critical surface expansion during a forging process. The critical surface expansion appears to decrease with increasing hydrostatic pressure. This may be due to the fact that the close contact between the materials necessary to obtain bonding is created by a micro-extrusion of the surfaces into each other. This may explain why the bond strength achieved by different processes, such as forging and extrusion, is quite different for the same value of the surface expansion. [ABSTRACT FROM AUTHOR]

The paper shows how the governing equations are modified by allowing a variation in yield stress throughout a deformation zone. The limitations imposed by these equations are discussed and a method is proposed to illustrate the effect of variable yield stress on the deformation pattern. From the study of a particular solution of plane strain extrusion, it is concluded that variation in yield stress should not markedly change the pattern of deformation from that appropriate to a non-hardening situation. This conclusion, therefore, gives support for the mean strain solution currently employed to accommodate strain hardening, particularly if this method is applied incrementally along the streamlines. [ABSTRACT FROM AUTHOR]

A critical assessment of the merits of core-spinning by means of comparisons of the strength and extension of core-spun yarns with all-staple-fibre yarns forms the basis of this paper. Core-spinning was done by introducing the filament under tension into the drafted strand as the latter entered the front rollers of the ring-frame. A 20-den (2.2-tex) nylon monofilament was used as core, and three types of staple-fibre covering were investigated. The effects of twist, pre-tension, and feeding arrangements on the geometrical disposition and tensile properties of the yarns were examined. Irnprovements in strength are, in general, realized at low twists by the incorporation of the filament and by further constraining it to occupy the core. The contribution of the components to the yarn strength and the process of breaking were also subjected to a detailed study. The studies reported provide an interesting insight into the extent of cohesion developed between the fibres during the straining of the yarn and its influence on the process of breaking and ultimately on yarn extension. [ABSTRACT FROM AUTHOR]

1. The primary response contributing to an overall inhibition of root growth by IAA is a concentration dependent shortening of the period over which the roots elongate. 2. Deformation of root cell walls under constant, externally imposed load is composed of a plastic and an elastic component. These components are separable under the usual conditions of mechanical analysis. 3. Treatment of intact roots for one hour in the presence of concentrations of IAA that normally promote shoot growth and, therefore, inhibit root growth, results in formation of a concentration dependent, IAA-induced plasticity component, not observable in untreated roots. The change in deformability may be indicative of specific wall components either synthesized or altered in the presence of IAA. 4. Half-maximal plasticity is induced by ca. 5 × 10-7 M of IAA, a concentration comparable to that for Avena coleoptiles. 5. Deformability induced by IAA-treatment is transient, reaching a maximum after approximately one hour. 6. That increased deformability may be associated with increased root growth is indicated by measurements of fresh weight changes of excised root sections in the presence and absence of IAA. The IAA-induced increase in fresh weight is also transient with a maximum after approximately one hour. The overall effect of IAA-treatment of root sections -is to reduce growth. 7. Ionic regulation of cell wall deformability is found to be similar to that reported for stem tissues. Addition of divalent calcium ions results in cell wall stiffening, an effect which is reversed in the presence of an excess of monovalent sodium or potassium ions. [ABSTRACT FROM AUTHOR]

An account is given of a study of the extent to which fibres were pulled through the web during needling that was made by incorporating one layer of coloured fibres at various positions in a 50-layer web. The number of needle locations at which tracer fibres appeared and the number and length of fibres were determined. Further studies of the occurrence of interlocking loops on the surface of a needled fabric are reported. [ABSTRACT FROM AUTHOR]

A brief summary of the structure of keratin fibres is followed by a review of their mechanical and allied properties. Among these properties are tensile stress-strain properties, stress relaxation, and creep, and torsional stress-strain properties and stress relaxation. The mechanism of supercontraction, properties of set fibres and disulphide-reduced fibres, and thermal transitions in keratin are also discussed. Finally, the various theoretical attempts that have been made to explain these properties are critically reviewed. [ABSTRACT FROM AUTHOR]

A study is reported of the bursting pressure and pressure-induced deformation for the stitched closure of inflated woven polypropylene-tape sacks with the 'flat' sides of the sacks constrained against fixed platens. This particular system was investigated as a simple analogue of a sack containing granular material and subjected to compressive forces on its "flat" sides. An Instron Tensile Tester was used to study the deformation behaviour to failure of cut-out samples of sack closure and sack fabric. An empirical model of bursting behaviour was derived from thin-walled-cylinder theory modified to suit bursting conditions for sacks. Instron-tester data are used to provide bursting limits, either force or extension at break, depending on how the model is formulated. The model is used to transcribe Instron-tester deformation into pressure deformation for comparison with actual inflation behaviour. [ABSTRACT FROM AUTHOR]

A new equation is proposed for the description of the static creep of dental amalgam. It is satisfactory for a wide range of stresses and strain rates in static creep experiments during steady state. The hypothesis was confirmed that creep of dental amalgam is determined by the low melting phases. [ABSTRACT FROM AUTHOR]

The over-all shear deformation, that is, the combined deformation of biaxial tensile and shear deformation is considered generally, and a theory by which the mechanical behaviour of fabrics in this slate can be determined is presented. Experiments are also described that were made to confirm the accuracy of these theories by using a new biaxial tensile tester for the measurement of the tensile and shearing properties of the fabrics and by using newly designed testing instruments for the measurement of yarn properties. Good agreement between the theoretical and observed data is shown, and the theories appear lo have considerable potentialities in the practical design of fabrics. [ABSTRACT FROM AUTHOR]

An account is given of experiments in which samples of wool fibres were heated in an oven for various times, and at different temperatures, and examined in a scanning electron microscope. Samples were also subjected to the Allwörden test and to a dye-absorption test. It is shown that, on exposure to dry heat, wool fibres retain their physical shape and characteristics, even under severe conditions, the only major change initially being discoloration. Only at temperatures of 160°C and above are serious physical changes, such as scale deformation and changes in X-ray-diffraction patterns, observed. [ABSTRACT FROM AUTHOR]

A model two-dimensional assembly of long straight viscoeiastic fibres of many different types arranged in various directions is analysed in terms of bending, creasing, and associated recovery behaviour. The fibres are assumed to be viscoelastic in both bending and torsion and subject to frictional restraints in both these modes of deformation. It is assumed that the model is relevant to the bending and creasing behaviour of woven and non-woven fabrics composed of fibres of one or more types. [ABSTRACT FROM AUTHOR]

The problems involved in making a mechanical analysis of bending deformations in textile fabrics are discussed. It is suggested that progress can be made by making simplifying assumptions concerning the geometry of fabric structure and deformation and using energy considerations to calculate forces and moments. Certain simple examples are given of the usefulness of this approach. A foundation is laid for the construction of a computer model that will, it is hoped, simulate the viscoelastic bending and creasing behaviour of textile fabrics from a knowledge of the bending and torsional viscoelastic properties of the constituent fibre(s) and their relative geometrical arrangement. [ABSTRACT FROM AUTHOR]

A new type of yarn structure, which has been named self-twist yarn, is described. It is a two-ply structure in which both the strand and plying twists alternate S and Z along the yam. The strength properties of the yarn and their dependence on the various yam parameters are given for 60/64s wool fibres, and it is shown that the strength can approach that of conventional yarns. [ABSTRACT FROM AUTHOR]

In wrinkling tests based on angular recovery from a fixed deformation, constraints imposed on the fibres by virtue of yarn or fabric construction are of secondary importance. When ageing effects have been eliminated, this results in similar wrinkle-ratings for all fabrics. Any performance differences subjectively assessed during wear arise from either fabric deformability or optical effects caused by differences in curvature. [ABSTRACT FROM AUTHOR]

A theoretical investigation of the tensile, flexural and torsional behaviour of crimped filaments has been made; the relationships describing the filament behaviour are presented in graphical and in analytical form, and are verified experimentally. Two results are of particular importance in routine textile testing: it is shown that the Young's modulus of staple fibres measured with a tensile-testing machine is not subject to significant error caused by crimp; and a new expression is proposed which enables the optimum tension for the routine yarn-crimp test to be calculated. [ABSTRACT FROM AUTHOR]

The relation between the creep behaviour (plasticity) and the proportion of the orthocortical material (expressed as ortho/para ratio) in five lambs' wools has been examined by means of electron-microscope techniques, in conjunction with thin sectioning. No correlation was found between the amount of orthocortical material, on the one hand, and either plasticity or helical conformation (the latter estimated by other workers) on the other. These results are supported by the observation of the structural differences, greater than hitherto thought, within both cortical segments (as indicated by the considerable variation in metal absorption—'staining'), and it is believed that these have the primary effect on the plasticity. The cells of intermediate morphological appearance and reactivity (between those of the two bilateral segments and referred to as meso-type) have a secondary influence in this respect. [ABSTRACT FROM AUTHOR]

In this work edge dislocations are introduced by plastic deformation in silicon planar diodes. The effects of the dislocations on the electrical properties, especially noise are studied. The noise spectra for the diodes under forward bias conditions show that the shot noise is relatively unaffected by the dislocations, and the 1/f noise is only affected when the dislocations emerge at a surface near the junction. The most striking feature of the spectrum is the existence of a visible generation-recombination noise, which seems to be due to fluctuations in the occupation of trapping centers in the space charge region introduced by the dislocations.
In this work, silicon planar diodes have been deformed so as to introduce in them dislocations, in order to study the effects of the latter on the p-n junction characteristics. The main parameter which was investigated was the electrical noise caused by the dislocations. The shot noise was shown not to depend on the dislocations, and the 1/f noise was only affected when the dislocations emerged at the surface of the device near the junction. However, G-R noise was shown to be a function of the dislocation density. A theory was developed in which the G-R noise was attributed to an electron trapping process caused by the dislocations in the depletion region. The trapping model was shown to be in very good agreement with the experimental observations.
The main conclusion which can be drawn from this work is that dislocations in planar silicon diodes effect the noise spectra in two ways. The first way in which this occurs is that the 1/f noise is increased if the dislocations intersect a surface near the junction. The second way is that G-R noise is produced by fluctuations in the occupancy of traps caused by the dislocations. [ABSTRACT FROM AUTHOR]

Analyzes the value of interrupting a map projection. Maximum angular deformation; Mean deformation for the land areas; Requirements for the interruption of oval equal-area projections.

Illustrates a particular oblique equal-area map for world distributions. Conceptual basis for oblique versus equatorial cases of world grids; Brief description of the particular base map; Angular deformation of the Sinu-Mollweide projection with two equatorial-case projections.

The article analyzes the mechanical and elastic properties of human dentin. An experiment is described and results are discussed. The ultimate compressive strength of dentin was found to be 43,100 psi. Pure and retarded elastic deformation were determined to compose dentin's total deformation below the proportional limit.

A model was constructed to simulate a one surface cavity preparation. Dentin disks of varying thickness served as the pulpal floor of the model. The deflection of the cavity floor was monitored when forces of the type used in condensing amalgam and gold foil restorations were applied. Deflection of the dentin occurred under this type of loading. The amount depended on the magnitude of the load and thickness of the dentin. A cement base reduced the deflection of the cavity floor. [ABSTRACT FROM AUTHOR]

Stereographic scanning electron micrographs of the fracture surfaces of amalgam beams that were broken by bending, and of the surfaces of polished and etched specimens of both fine cut and spherical particle alloys, did not reveal discrete grain boundary segregations. However, evidence of microplastic deformation and intragranular inhomogeneities was found. [ABSTRACT FROM AUTHOR]

Using steel spherical indenters, the relationship between indentation diameter and load was determined for a mature amalgam. The form of this relationship allowed the regions of elastic and plastic deformation to be identified; hence, Young's modulus and yield point could be calculated. Local contact stresses in the mouth also were estimated. [ABSTRACT FROM AUTHOR]