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In this study we examine the spectral properties of stiffness degradation at the constitutive level and at the levels of finite elements and their assemblies. The principal objective is to assess the effects of defects on the elastic stiffness properties at different levels of observation. In particular, we are interested in quantitative damage measures, which characterize the fundamental mode of degradation in the form of elastic damage at the level of constitutive relations and at the level of finite elements and structures.

The main factors affecting consumers when selecting denim garments are aesthetic, appearance and fashion. Besides these factors, comfort and performance properties of the denim garments during usage are very important. The purpose of this paper is to determine the effects of different finishing processes on the performance properties of 100 percent cotton and 98 percent cotton+2 percent elastane denim fabrics.

The research design for this study consists of experimental study. In order to evaluate the effects of finishing on the performance properties of fabrics, eight types of fabrics were selected for evaluation. Rigid, resin, bleaching and softening type fabrics with and without elastane were analyzed statistically.

The results obtained in the study clearly showed that the types of finishing and elastane fiber in the fabric structure had a significant influence on mechanical and comfort properties of denim fabrics.

As a result of the literature review, it was seen that there were limited studies concerning mechanical, functional and comfort properties of denim fabrics together. In this study, the effects of finishing processes on the tear strength, stiffness, drape, mechanical and thermal comfort characteristics were deeply evaluated.

A simple beam element is developed for the solution of large deflection problems. The total Lagrangian formulation is based on the kinematic relations proposed by Reissner for finite rotations and stretching as well as shearing of plane beams. The motion is discretized by linear expansions of the global displacement components and the cross‐sectional rotation in two‐dimensional Euclidean space yielding a simple beam element with three degrees of freedom at the two nodes. The shear locking is reduced by selective integration in order to eliminate the spurious shear constraint similar to interdependent variable interpolation. The large rotation formulation is compared with two forms of moderate rotation theories which have been used in the past to develop the geometric stiffness properties for linear stability analysis of the so‐called Mindlin plate elements. The predictive value of different geometric stiffness approximations is assessed with several examples which range from the static and kinetic stability analysis of the classical Euler‐column to the large deflection problem of a clamped beam.

A series of all-atom molecular-level computational analyses is carried out in order to investigate mechanical transverse (and longitudinal) elastic stiffness and strength of p-phenylene terephthalamide (PPTA) fibrils/fibers and the effect various microstructural/topological defects have on this behavior. The paper aims to discuss these issues.

To construct various defects within the molecular-level model, the relevant open-literature experimental and computational results were utilized, while the concentration of defects was set to the values generally encountered under “prototypical” polymer synthesis and fiber fabrication conditions.

The results obtained revealed: a stochastic character of the PPTA fibril/fiber strength properties; a high level of sensitivity of the PPTA fibril/fiber mechanical properties to the presence, number density, clustering and potency of defects; and a reasonably good agreement between the predicted and the measured mechanical properties.

When quantifying the effect of crystallographic/morphological defects on the mechanical transverse behavior of PPTA fibrils, the stochastic nature of the size/potency of these defects was taken into account.

Fiber-reinforced armor-grade polymer-matrix composite materials with a superior penetration resistance are traditionally developed using legacy knowledge and trial-and-error empiricism. This approach is generally quite costly and time-consuming and, hence, new (faster and more economical) approaches are needed for the development of high-performance armor-grade composite materials. One of these new approaches is the so-called materials-by-design approach. Within this approach, extensive use is made of the computer-aided engineering (CAE) analyses and of the empirically/theoretically established functional relationships between an armor-grade composite-protected structure, the properties of the composite materials, material microstructure (as characterized at different length-scales) and the material/structure synthesis and fabrication processes. The paper aims to discuss these issues.

In the present work, a first step is made toward applying the materials-by-design approach to the development of the armor-grade composite materials and protective structures with superior ballistic-penetration resistance. Specifically, CAE analyses are utilized to establish functional relationships between the attributes/properties of the composite material and the penetration resistance of the associated protective structure, and to identify the combination of these properties which maximize the penetration resistance. In a follow-up paper, the materials-by-design approach will be extended to answer the questions such as what microstructural features the material must possess in order for the penetration resistance to be maximized and how such materials should be synthesized/processed.

The results obtained show that proper adjustment of the material properties results in significant improvements in the protective structure penetration resistance.

To the authors’ knowledge, the present work is the first reported attempt to apply the materials-by-design approach to armor-grade composite materials in order to help improve their ballistic-penetration resistance.

A 3‐dimensional formalism adapted to critical speed and stability analysis of rotating machinery is presented. Gyroscopic effects are properly taken into account in the expression of the kinetic energy through a proper kinematic description which takes account of the local changes of angular velocity induced by the deformation. Two approaches are suggested according to the respective stiffness and geometric properties of the rotating and fixed parts: the rotating frame approach and the inertial frame approach. In both cases, an axisymmetric finite element modelling of the rotor is proposed which takes into account the 3‐dimensional nature of the system while keeping the number of degrees of freedom to a reasonable level. In order to perform the stability analysis, a preliminary reduction of the system is achieved using the component mode method. Critical speeds are calculated next either by the classical sweeping procedure or by a direct method when the restrictive conditions of its applicability are met. The concepts proposed are then applied to an example in order to demonstrate their adequacy.

Dehydrated bacterial cellulose’s (BC) intrinsic rigidity constrains applicability across textiles, leather, health care and other sectors. This study aims to yield a novel BC modification method using glycerol and succinic acid with catalyst and heat, applied via an industrially scalable padding method to tackle BC’s stiffness drawbacks and enhance BC properties.

Fabric-like BC is generated via mechanical dehydration and then finished by using padding method with glycerol, succinic acid, catalyst and heat. Comprehensive material characterizations, including international testing standards for stiffness, bending properties (cantilever method), tensile properties, moisture vapor transmission rate, moisture content and regain, washing, thermal gravimetric analysis, derivative thermogravimetry, Fourier-transform infrared spectroscopy and colorimetric measurement, are used.

The combination of BC/glycerol/succinic acid dramatically enhanced porous structure, elongation (27.40 ± 6.39%), flexibility (flexural rigidity of 21.46 ± 4.01 µN m; bending modulus of 97.45 ± 18.20 MPa) and moisture management (moisture vapor transmission rate of 961.07 ± 86.16 g/m²/24 h; moisture content of 27.43 ± 2.50%; and moisture regain of 37.94 ± 4.73%). This softening process modified the thermal stability of BC. Besides, this study alleviated the drawbacks for washing (five cycles) of BC and glycerol caused by the ineffective affinity between glycerol and cellulose by adding succinic acid with catalyst and heat.

The study yields an effective padding process for BC softening and a unique modified BC to contribute added value to textile and leather industries as a sustainable alternative to existing materials and a premise for future research on BC functionalization by using doable technologies in mass production as padding.

The purpose of this paper is to investigate the effect of laundering on the drape, shear, and bending properties of bottom weight fabrics.

Six bottom‐weight 100 percent cotton fabrics were included. Collier's Drape Tester was utilized to obtain drape values. Bending and shear values were measured on the KES‐F Shear Tester and the Pure Bending Tester. Three laundering cycles (unlaundered, one and five home launderings) following AATCC methods were explored.

Laundry cycle did not have a significant effect on fabric drape, shear or bending properties. However, drape values increased overall, while shear and bending modulus and hysteresis decreased, resulting in a more drapable, pliable fabric after five laundry cycles.

Future research examining a wider variety of fabrics and conducting a greater number of laundry cycles to approximate an average yearly number of laundry cycles is recommended. An expansion of this preliminary study should give more conclusive evidence of the trends observed.

Objective measurement of drape and fabric mechanical properties related to drape after laundry treatments would assist the apparel manufacturer in developing laundry recommendations based on the fabric's performance and in selecting fabrics which maintain their drape characteristics, mechanical properties, and dimensional stability with use. Higher quality garments with increased consumer satisfaction would result.

The rigid spherical particle models proposed in the literature for modeling fracture in rock have some difficulties in reproducing both the observed macroscopic hard rock triaxial failure enveloped and compressive to tensile strength ratio. The purpose of this paper is to obtain a better agreement with the experimental behavior by presenting a 3D generalized rigid particle contact model based on a multiple contact point formulation, which allows moment transmission and includes in a straightforward manner the effect of friction at the contact level.

The explicit formulation of a generalized contact model is initially presented, then the proposed model is validated against known triaxial and Brazilian tests of Lac du Bonnet granite rock. The influence of moment transmission at the contact level, the number of contacts per particle and the contact friction coefficient are assessed.

The proposed contact model model, GCM‐3D, gives an excellent agreement with the Lac du Bonet granite rock, strength envelope and compressive to tensile strength ratio. It is shown that it is important to have a contact model that: defines inter‐particle interactions using a Delaunay edge criteria; includes in its formulation a contact friction coefficient; and incorporates moment transmission at the contact level.

The explicit formulation of a new generalized 3D contact model, GCM‐3D, is proposed. The most important features of the model, moment transmission through multiple point contacts, contact friction term contribution for the shear strength and contact activation criteria that lead to a best agreement with hard rock experimental values are introduced and discussed in an integrated manner for the first time. An important contribution for rock fracture modeling, the formulation here presented can be readily incorporated into commercial and open source software rigid particle models.

The purpose of this paper is to prepare nano size micro-emulsion co-polymer particles based on butyl acrylate (BA)/acrylic acid (AAc) with high monomer/surfactant ratio. The study involved the application of the prepared micro-emulsions co-polymers as textile pigment printing binders.

The micro-emulsion co-polymerisations processes were carried out with different mixtures of BA and AAc using modified process. Sodium dodecyl sulphate (SDS) and potassium peroxy disulphate/glucose were used as emulsifier and redox initiator, respectively. The prepared emulsion co-polymer was characterized via spectroscopic measurements, FT-IR, 1H-NMR and transmission electron microscope (TEM), in addition to thermal analysis. The prepared micro-emulsion co-polymers were applied as binders for pigment printing process onto cotton fabric, polyester and cotton/polyester blend by using flat screen technique. The optimum curing conditions were determined, colour strength and fastness properties of pigment printed areas to light, washing, perspiration and rubbing were evaluated. In addition, stiffness of the prints was studied.

The achieved results indicated that particle size and homogeneity of the prepared micro-emulsions depend on monomers weight ratio, initiator and emulsifier concentrations. On the other hand, the prints obtained using the prepared binders with optimum conditions have satisfactory fastness, good handle and high colour yield.

Monomers were continuously and slowly added into the polymerising system with mild stirring to avoid disturbing the stability of the micro-emulsion. Also, emulsifier and initiator concentrations should be controlled to avoid coagulation.

The research provides textile pigment printing binder with nano particle size within the range of 24-48 nm. Using the prepared nano binders in pigment printing enhances the stiffness, handle, and fastnesses properties of the prints.

The prepared co-polymer binders showed high-performance physico-mechanical properties; in addition, the ultimate goal of this study is to prepare a nano size binder with high monomer/surfactant ratio using a modified micro-emulsion process.