Hazim Ali Al-Qureshi - Academia.edu (original) (raw)

Papers by Hazim Ali Al-Qureshi

International Journal of Machine Tool Design and Research, 1976

Abstract Elastomers are increasingly being used as energy transfer mediums for various metal form... more Abstract Elastomers are increasingly being used as energy transfer mediums for various metal forming operations. The present paper shows that, with proper tool design, sizing, beading and even cropping of thin-walled tubes can be achieved with the help of elastomers. Various relevant parameters are examined, and an approximate theory for predicting the cropping load and ram movement is presented.

International Journal of Mechanical Sciences, 1997

The paper presents an experimental and theoretical analysis of tube inversion process under quasi... more The paper presents an experimental and theoretical analysis of tube inversion process under quasi-static and dynamic loading conditions. The aim of the work is to propose a method of predicting the dynamic inversion load based on the quasi-static data. The method employs the principle of conservation of energy of the body in collision which is totally dissipated through plastic deformation

Anais do(a) Anais do Congresso Brasileiro Interdisciplinar em Ciência e Tecnologia, 2022

Cerâmica, Sep 1, 2014

A combinação de propriedades físicas e mecânicas qualificam as cerâmicas para aplicações em siste... more A combinação de propriedades físicas e mecânicas qualificam as cerâmicas para aplicações em sistemas de proteção balística. Materiais cerâmicos normalmente formam a primeira camada de um sistema de blindagem mista, recebendo o impacto inicial do projétil, e dissipando grande parte da energia cinética ao fragmentar o projétil. Os principais materiais cerâmicos para blindagem balística são a alumina, o carbeto de silício e o carbeto de boro. Novas técnicas de processamento de materiais cerâmicos além do modelamento do mecanismo de fratura sob alto impacto energético são áreas que têm sido amplamente investigadas. Desenvolvimentos em particular na área de compósitos de matriz cerâmica, reforçados com fibras ou com base na transformação por tenacificação abrem novas perspectivas de uso e de melhor desempenho de sistemas de proteção balística a base de materiais cerâmicos. Palavras-chave: proteção balística, blindagem, impacto, alumina, carbeto de silício, carbeto de boro, compósitos de matriz cerâmica.

Advanced materials and technologies, 2013

An important aspect of clay paste extrusion is the pressure as a function of extruded velocity/di... more An important aspect of clay paste extrusion is the pressure as a function of extruded velocity/distance traveled. Therefore, the present theory concentrates on deriving basic equations that control the clay paste flow behavior of rectangular extrusion process during the steady-state flow. The main parameters which control the extrusion pressure are the effective stress in compression of the clay paste, the geometry of extrusion tools and billet, operational conditions and the coefficients of friction between the barrel and the die land surfaces. The theoretical extrusion pressure results were analyzed and discussed thoroughly. Finally, it can be concluded that the present theoretical analysis serves to place the present approach in the context of work on other extrudable materials of different geometry. In addition, it can be used as an effective tool for evaluating and obtaining clay paste materials with optimized properties for extrusion process in the ceramic industry

Journal of Mechanical Working Technology, 1978

Journal of the European Ceramic Society, 2017

The influence of preexisting defects and the generation of new ones during flash sintering was st... more The influence of preexisting defects and the generation of new ones during flash sintering was studied in 3YSZ. Weibull statistics was used to analyse mechanical testing data from flash and conventionally sintered specimens with equal densification. The obtained values for Weibull modulus and characteristic strength are 6.09 and 371 MPa for the conventionally sintered samples, respectively, and 5.92 and 506 MPa for the flash sintered samples. It can be inferred that flash sintering does not alter significantly the defect distribution on the studied material. Preexisting defects were manufactured with rice starch as a pore forming agent, in 5, 10 and 15 vol%. Those samples were flash sintered in isothermal and constant heating rate experiments. The experiments show that there is no noticeable difference on the incubation time and the onset temperature for flash sintering.

International Journal of Machine Tool Design and Research, 1986

... Assistant Professor, lnstituto Tecnol6gico de Aeronfiutica--ITA, Silo Jos~ dos Campos, SP, Br... more ... Assistant Professor, lnstituto Tecnol6gico de Aeronfiutica--ITA, Silo Jos~ dos Campos, SP, Brasil. ~Professor of Metal Forming, Instituto Tecnol6gico de Aeromiutica--fTA, Silo Jos6 dos Campos, SP, Brasil. ... 6) X -- 2x -- total displacement of the dome (Fig. ...

RESUMO Na conformação de materiais cerâmicos usa-se comumente o conceito de plasticidade. Este te... more RESUMO Na conformação de materiais cerâmicos usa-se comumente o conceito de plasticidade. Este termo se refere a um modo particular de comportamento mecânico. Um material cerâmico plástico exibe uma deformação permanente sem ruptura quando uma carga compressiva produz uma tensão de cisalhamento que excede a resistência ao escoamento do material. Para uma massa cerâmica plástica, observa-se um comportamento elástico mensurável antes que ocorra o escoamento e quando a carga aplicada é removida. Neste trabalho foi desenvolvido um modelo matemático, utlizando-se diagramas tensão x deformação sob compressão, a partir de conceitos aplicados da teoria de plasticidade. Palavras-chave: plasticidade da argila, cerâmica, modelo, coeficiente de atrito.

Matéria (Rio de Janeiro)

A novel kind of short natural fiber obtained from mineral resources, which consists mainly of pur... more A novel kind of short natural fiber obtained from mineral resources, which consists mainly of pure amorphous SiO2, was characterized and applied as a reinforcing agent in epoxy resin. Natural amorphous silica fibers (NASF) were incorporated in epoxy resin and the obtained composites were mechanically tested. The effect of the treatment of NASF chemically modified with aminosilane as well as the aspect ratio of the fibers on the mechanical properties of the composite were evaluated and compared with properties obtained with FNSA without treatment. The results obtained show that these natural fibers are potential candidates for the substitution of short glass fibers as a reinforcement phase in polymer composites, since the mechanical properties obtained were in all cases similar or superior to the ones obtained with commercial short glass fibers.

Materials & Design, 2002

This paper presents analytical results whereby approximate equations are derived to provide a qua... more This paper presents analytical results whereby approximate equations are derived to provide a quantitative method for predicting spring-back behaviour and residual stress distributions. Comparisons between experimental and theoretical results of spring-back have shown good agreement. The experiments were performed using a special industrial machine to determine the load and spring-back at the end of each test. Both experiments were performed on aluminium tubes with different geometry and having the same mechanical properties. Various parameters associated with these techniques, such as the internal support to avoid fracture and collapse of the tubes and others factors, will also be discussed.

Ceramics International, 2015

All-oxide ceramic matrix composites produced by a novel route based on the lamination of thermopl... more All-oxide ceramic matrix composites produced by a novel route based on the lamination of thermoplastic prepregs are investigated. This route allows for the production of composites with very homogeneous microstructures and a reduced amount of matrix cracks. Nextel TM 610 alumina woven fabric is used here to reinforce a porous oxide matrix composed of 80 vol% Al 2 O 3 and 20 vol% ZrO 2. The mechanical behavior of composites submitted to different heat treatments is investigated under 4-point bending and short beam shear. Results show that composites with low interlaminar shear strength present a graceful failure under 4-point bending, characterized by a stepwise stress reduction upon straining beyond the peak stress. The fracture of such composites is accompanied by a series of interfacial delamination events, which enhance energy dissipation during failure. An increase of the interlaminar shear strength due to matrix densification causes a loss of the stepped stress-strain behavior. Nevertheless, fiber-related toughening mechanisms such as crack deflection and bridging still ensure inelastic deformation up to failure of these composites.

Journal of Composites Technology and Research, 1982

The mandrel is one of the most important components of the filament-winding process. Careful atte... more The mandrel is one of the most important components of the filament-winding process. Careful attention must be paid to the mandrel design, material selection, and all other relevant manufacturing and processing parameters involved in fabricating a vessel. The material selected for the mandrel should have a substantial strength and be capable of retaining dimensional accuracy of the required wound wessel. The stiffness of the mandrel material plays an important role in governing the residual filament stresses in the wound products.

The main purpose of this paper is to present the development , manufacture and assembly of a prot... more The main purpose of this paper is to present the development , manufacture and assembly of a prototype of truck body panels made from banana fibre reinforced composite and hybrid composite . Mechanical properties tests of these laminates were performed, and based on these parameters, the panels were designed to meet certain requirements. A quasi all banana reinforced composite car was made and called "MANACA". Performance tests over the last few years have demonstrated very encouraging results. In addition, the tool of hybridization proved to be very effective at this stage of development of natural fibre composite structures.

Materials and Manufacturing Processes, 2001

This article describes an experimental machine using an elastomer rod for developing junctions on... more This article describes an experimental machine using an elastomer rod for developing junctions on aluminum tubes, and is put forward as an effective process under a limited range of operational conditions. The operation is achieved by applying loading–unloading cycles to the tube and the elastomer simultaneously. The success of the operation is governed by the mechanism that controls the relationship

Journal of the American Ceramic Society, 2011

ABSTRACT In the present study, fiber‐matrix compatibility in an all‐oxide ceramic composite is ex... more ABSTRACT In the present study, fiber‐matrix compatibility in an all‐oxide ceramic composite is examined. Reaction‐bonding aluminum oxide is used as porous matrix to ensure weak interfaces with fibers. Matrix cracks have been deflected around the interface for sintering temperatures up to 1300°C, due to the effectiveness of porous matrix in enabling damage tolerance. Above 1300°C, densification of the matrix resulted in brittle fracture of the samples, with matrix cracks going through the fibers. Observation of fracture surfaces confirmed the fiber pull‐out phenomenon up to processing temperatures of 1300°C. The well‐known He and Hutchinson criteria for crack deflection was used to predict debonding behavior at the fiber‐matrix interface as a function of matrix porosity. Furthermore, evaluation of the microstructure evolution of Nextel™ 610 alumina fibers showed a pronounced grain coarsening at sintering temperatures above 1300°C. Changes in crack deflection behavior and fiber microstructure of a composite sample aged for 100 h are also presented.

Journal of Materials Processing Technology, 1999

In recent years, considerable attention has been given to the development and utilization of natu... more In recent years, considerable attention has been given to the development and utilization of natural ®bres. The main application of these materials as composites has been directed towards the automotive industries. The major advantages of natural ®bre reinforced composites are abundance, biodegradability and low cost. However, little research has been focused on the mechanical behaviour of the ®bre/matrix interface, and its in¯uence on the mechanical behaviour of the composite material. For this reason the aim of the present work is to present a mathematical model to estimate the angle of contact between the mono®lament and the matrix. Comparison between the theoretical and experimental results showed good agreement. Needless to say, the angle of contact is one of the predominant parameters that controls the ®nal mechanical behaviour of the composites, such as rigidity and strength. Other relevant parameters are also presented.

Journal of Materials Processing Technology, 2005

This paper examines the influence of surface roughness which is related directly to the grain siz... more This paper examines the influence of surface roughness which is related directly to the grain size to the onset of plastic instability and necking conditions. A theoretical analysis is presented of thickness and grain size dependence on the limit strains in the process of stretch forming of anisotropic thin sheet metals. The theory assumes that the roughness can be represented