Murat Demiral

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• Professor
• Professor at American University of the Middle East

This article provides an overview of micromilling operation with a focus on the tool wear and discusses prediction models, monitoring techniques, wear mechanisms, measurement methods, and evaluation approaches used to analyze or predict tool wear within the last two decades. In its conclusion, the article highlights future trends and research gaps...

Steel T-profiles are extensively used across various sectors due to their versatility and reliability. Spot welding plays a crucial role in their production. These profiles are subjected to cyclic bending loads in numerous engineering applications. Understanding the failure mechanisms is essential for enhancing fatigue resistance and extending the...

Robust and lightweight joining techniques are crucial for good performance and safety in advanced engineering applications, particularly in the automotive and aerospace sectors. While traditional methods such as bolting, riveting, and resistance spot welding have been central to structural assembly, they face limitations under modern engineering de...

Steel T-profiles with the spot-welding manufacturing process are extensively used in various sectors such as construction, automotive, renewable energy, etc., due to their versatility and reliability. These profiles are exposed to various loading modes during their service life, which include axial, bending, shear, torsional, or combinations thereo...

This study delves into the exploration of the fatigue performance of a structure that has been spot-welded and is being loaded with torsional fatigue. The extended finite element method (XFEM) was applied to simulate the intricate interaction of spot welds in response to cyclic loading. The developed model was validated through experiments. The inf...

This study presents novel mechanochemical methods for the synthesis and chemical modification of bismuthene nanosheets (BINS) using a high‐speed blender and planetary ball milling. Atomic force microscopy (AFM) measurements confirmed successful exfoliation of 1.5‐nm BINS. Epoxy/BINS nanocomposites exhibited enhanced mechanical properties, thermal s...

To accurately predict the behavior and mechanical damage of sheet metal during hot forming process, the use of advanced thermomechanical modeling and precise identification of the constitutive parameter are required. This paper proposes a novel identification approach for constitutive parameters that relies on multiple regression and the shape inde...

In the present work, the effects of various filler types and content on the characteristics and properties of styrene-butadiene rubber (SBR) were studied. This study prepared SBR filled with different fillers: kaolin, metakaolinite, synthetic zeolite Na-A, alumina (Al2O3) nanoparticles, and hybrid filler (synthetic zeolite Na-A/Al2O3). The silane c...

This study investigates the impact of two innovative methods, namely, intermittent metal part reinforcement and countersinking, on the strength of single lap joints (SLJs). In the former method, metal inserts are strategically integrated within the adhesive layer, while the latter involves the application of countersinks on the adherends to create...

Spot welding is the most common method of assembling sheet materials due to its ease of application, effectiveness, and low cost. Fatigue of spot-welded structures is regarded as one of the major concerns in automotive, marine and aviation industries, where simulation techniques play a critical role in reliable product development. This study focus...

The lattice rotation behavior of low-carbon (LC) steel subjected to tensile deformation was studied by electron backscatter diffraction (EBSD). The EBSD scans of the same region were taken before and after tensile deformation. The rotation of the grains was found to depend on a number of factors like the initial orientation, the size of the grains,...

Due to their effective and affordable joining capabilities, resistance spot-welded (RSW) structures are widely used in many industries, including the automotive, aerospace, and manufacturing sectors. Because spot-welded structures are frequently subjected to cyclic stress conditions while in service, fatigue failure is a serious concern. It is esse...

Step lap joints are kinds of lap structures, where butted laminations of each layer are consecutively offset in succeeding layers in the same direction. They are mainly designed this way to reduce the peel stresses at the edges of the overlap area observed in single lap joints. In their service, lap joints are often subjected to bending loads. Howe...

Single shear or single lap joints are the most prevalent type of adhesive joints used in advanced engineering applications, where they are exposed to fatigue loadings in their services. Although their mechanical performances under static loading have been investigated extensively, the studies related to the fatigue performances were limited. For th...

In many technical domains, adhesively bonded joints have been employed extensively. These joints perform poorly against peel stresses despite having good shear characteristics. A step-lap joint (SLJ) is one of the techniques used to reduce the peel stresses at the edges of the overlap area to avoid damages. In these joints, the butted laminations o...

The awareness of developing eco‐friendly polymer composites via green chemistry attract much attention in the recent years. In the current work, we explore preparing functional epoxy/ graphene nanocomposites using mechanochemical approach. Graphene platelets (GnPs) were modified with long‐chain surfactant via high‐energy ball milling. Modified‐GnPs...

The effect of deformation on the evolution of crystallographic texture in a Ti-15V-3Cr-3Sn-3Al (Ti-15333) alloy after unidirectional cold rolling was studied experimentally and numerically in the present investigation. An optical microscope (OM) and scanning electron microscope (SEM) were used to study the microstructures, while the crystallographi...

Bonded joints used in wing sections and frames of aircraft structures are mostly exposed to cyclic loadings instead of static ones during their services. Bending types of dynamic loadings are mostly encountered. In this study, the fatigue response of a single lap joint (SLJ) exposed to bending loading was studied with the developed advanced finite-...

Friction stir welding (FSW) of polymeric materials has recently attracted significant attention. Herein, we present the effect of the tool pin profile on the FSW of high-density polyethylene (HDPE) joints through joint experimental analysis and thermomechanical simulations. For analysis of pin profile effects on the thermomechanical properties of H...

Laser additive manufacturing is a promising approach to prepare near-neat shape parts from Al nanocomposites with high mechanical and tribological properties. Owing to its lubricious nature, boron nitride nanosheets (BNNSs) were added into AlSi10Mg alloy via high-speed ball milling and laser metal deposition (LMD) to manufacture self-lubricating Al...

When lightweighting studies are examined, thermoplastic matrix composites come to the fore as they have a high specific strength, are recyclable, and can be formed by thermoforming. Some obscurity needs to be overcome for the rapid forming of three-dimensional parts from laminated thermoplastic composites. In this study, deep drawing experiments we...

The micro cutting process differs significantly from its counter partner — the macro-cutting process — due to the fact that the uncut chip thickness is comparable with the crystal size of the workpiece and the cutting edge radius. In this study, the effects of cutting tool geometry including its nose radius and rake angle as well as its frictional...

A size effect is exhibited by metals in cutting processes at small scales: a nonlinear escalation in the cutting energy per unit volume with a decrease in the thickness of the uncut chip. To understand this phenomenon, a numerical model of orthogonal micro-cutting of f.c.c. single-crystal copper was developed, and three different depths of cut (0.8...

The abrasive water jet (AWJ) cutting technique is one of the promising techniques used in machining of composite materials due to lack of thermal damage, lower tool wear and higher productivity. In this study, the AWJ cutting of a cross-ply CFRP laminate was investigated experimentally and numerically. The purpose is to understand the underlying ph...

The influence of cutting speed and temperature softening was extensively investigated for conventional cutting process. However, this has not been addressed adequately for micro-cutting, especially of the single crystals, where the depth of cut is in the same range or even smaller than the average grain size of a polycrystalline aggregate. To this...

Modelling of micro milling process is still one of the most challenging research topics. This paper presents a new 3D SPH-FEM technique used to model micro end milling operation of titanium alloy. Titanium alloys are known as difficult to machine materials because of their thermo-mechanical properties. The low thermal conductivity of these alloys r...

Modelling of micro milling process is still one of the most challenging research topics. This paper presents a new 3D SPH-FEM technique used to model micro end milling operation of titanium alloy. Titanium alloys are known as difficult to machine materials because of their thermo-mechanical properties. The low thermal conductivity of these alloys r...

In today’s automotive industry, the thick sheet materials used in the regions where safety is at the forefront have been replaced with thin and more durable sheets. Deep drawing has been widely used in their processing. The parameters affecting their formability quality need to be identified. In this study the appropriate corner radius value for th...

In latest years small scale machining has been widely used in advanced engineering applications such as medical and optical devices, micro- and nano-electro-mechanical systems. In micromachining of metals, a depth of cut becomes usually smaller than an average crystal size of a polycrystalline structure; thus, the cutting process zone can be locali...

Vacant vascular channels within fiber-reinforced composites offer various functionalities ranging from self-repair and healing, damage detection, to thermal management. However, these channels affect the structure of the composite and can alter the stress distribution when subjected to mechanical loads. This study aims to investigate the bending lo...

Effects of underwater friction stir welding tool pin profiles were studied on mechanical properties of AA5182 alloy and St-12 steel dissimilar joint. For this purpose, frustum, triangle, cubic, and hexagonal pin profiles were selected. Thermal history, microstructure analysis, tensile strength, and hardness of joint lines were assessed. The obtaine...

Thermosets possess diverse physical and chemical properties and thus they are widely used in various applications such as electronic packaging, construction, and automotive industries. However, their poor thermal conductivity and weak mechanical performance jeopardize their continual spread in modern industry. In this study, boron nitride nanosheet...

Components of aircraft structures suffer from various intrinsic stress concentrations due to holes located at mechanical joints. Critical situations arise where two or more holes are placed in proximity in the structure such that their associated stress fields interact. In this study, the failure behaviour of loaded perforated carbon/PPS plates wit...

This research is deal with thermal buckling and post-buckling of carbon nanotube/fiber/polymer composite beams. The beam is considered to be under uniform temperature rise. Firstly, the effective material properties of a two phase nanocomposite consisting of CNT and polymer are extracted. Then, the modified Chamis rule is utilized to obtain the equ...

Hybrid nanocomposite materials have opened the way for more promising applications in the areas of optics, electronics, Ionics, mechanics, energy, environment, biology and medicine. In this work hybrid nanocomposite materials were synthesized, by mechanical stirring method, using SiO2+ZrO2+TiO2 nanoparticles with different percentages (4 wt.% to 10...

This study aimed to investigate the fracture behavior of a cracked orthotropic FGM medium when exposed to an in-plane harmonic load. The mechanical feature of the medium exponentially varied along the y-axis. Using the Fourier transform method, stress was analyzed by assessing Volterra edge dislocation in orthotropic FGM media. The obtained solutio...

This paper aims to investigate the crashworthiness performance of thin-walled tubes under quasi-static conditions both experimentally and numerically. Single-cell and multi-cell tubes made of aluminum were tested under quasi-static compressive loading. A three-dimensional finite element (FE) model accounting for the damage in the constitutive equat...

Hybrid nanocomposite materials have opened the way for more promising applications in the areas of optics, electronics, Ionics, mechanics, energy, environment, biology and medicine. In this work hybrid nanocomposite materials were synthesized, by mechanical stirring method, using SiO2+ZrO2+TiO2 nanoparticles with different percentages (4 wt.% to 10...

In this paper, the size effect in unidirectional (UD) laminated glass-fibre reinforced plastic (GFRP) composites subjected to quasi-static bending loading was investigated: the sensitivity of a specimen’s mechanical behaviour and failure mechanism to its geometry was studied. Composite beams with different numbers of 0° unidirectional plies were te...

Interply and interplay damage behavior of glass fiber composites with microvascular channels were investigated in this study. Short beam flexural tests and finite element analysis were performed according to ASTM D2344 for two stacking configurations, [90/0]3s and [0/90]3s. Specimens with and without channel (control specimens) were analyzed to inv...

Blanking and piercing shearing processes have been widely used to manufacture workpieces for industrial, commercial and testing purposes. During the operation, the punch is exposed to higher stresses and, due to the cycled contact of opposite surfaces, it can be worn significantly. As its surface directly affects the quality of sheet products and c...

In the present work, the microstructure and texture evolution of interstitial free (IF) steel during cold rolling was studied experimentally and also through simulations. Stored energy and geometrically necessary dislocation (GND) density maps were calculated from the electron backscattered diffraction (EBSD) data. The evolution of crystallographic...

This paper presents a study of the progressive damage of 5-harness satin weave carbon/PPS composite plates having three layers through experimental and numerical investigations. Uniaxial tensile tests were conducted for three different orientations of the composite material samples (warp, diagonal and weft) for their characterization at room temper...

In this work, the mixed mode fracture of woven carbon fiber composite is performed to measure the fracture force and to calculate the fracture toughness of the composite. A compact tension shear fixture is modeled and fabricated for the mixed mode fracture test. Compact tension specimen were made from woven carbon fiber epoxy that was fabricated us...

In this paper, the response of adhesively-bonded single lap joints (SLJs) with angle-plied composite adherends subjected to flexural loading was investigated. The experiments were carried out for the adherends, glass reinforced polymer matrix, with three kinds of stacking sequence. A three-dimensional finite element (FE) model was developed using A...

This study evaluates the effects of the overlap length and different adherend materials with different thicknesses on the mechanical performance of the bolted (BJ), adhesively bonded (ADJ) and hybrid joints (HJ) subjected to quasi-static axial tensile loading. The three different joints were fabricated and tested according to 36 different variances...

Mechanical and electrical properties of graphene and carbon nanotube reinforced epoxy adhesives: Experimental and numerical analysis

Carbon nanomaterials secure promises of incorporating exceptional mechanical performance and multifunctional properties into polymers. However, questions concerning type of carbon nanofiller, fraction and corresponding change in relevant property are yet to be answered. In this study, graphene platelets (GnPs) and carbon nanotubes (CNTs) were added...

In line with the developments in advanced engineering applications such as aerospace and automotive industries, the techniques of joining similar and dissimilar materials have become a crucial issue, i.e. the need for a stronger joint has significantly grown. Compared to conventionally used bolted, riveted and pinned joints, adhesively bonded joint...

In the last decades, composite materials have been increasingly used in advance engineering fields such as aerospace and automobile industries due to their advantages in terms of stress concentrations, structural weight and manufacturing. Joining composite parts in such applications has been increasingly achieved by adhesives compared to welded, ri...

This work is devoted on the synthesized new hybrid nanocomposite materials by using mechanical stirring method through a combination of different types of material; epoxy based matrix and nanofiller (TiO2 nanoparticles) as a reinforcement material. In additional this paper studies the effect of TiO2 nanoparticles with percentage 2-8 wt% added to ep...

Modelling of micro-/nano-indentation of single crystals has been developed extensively to elucidate experimentally observed features such as the size effect, pile-up phenomenon and lattice rotations. The indentation size effect (ISE) of three types of single crystals, i.e. f.c.c. copper single crystal, b.c.c. ß phase of Ti-6Al-4V (ß-Ti-64) and b.c....

A calibrated model of enhanced strain-gradient crystal plasticity is proposed, which is shown to characterize adequate deformation behaviour of bcc single crystals of a β-Ti alloy (Ti-15-3-3-3). In this model, in addition to strain gradients evolving in the course of deformation, incipient strain gradients, related to a component’s surface-to-volum...

High strength aluminium alloys that are produced through forming and joining processes are widely used in aerospace components. The ductile failure in these metals occurs due to the evolution and accumulation of microscopic defects, such as microvoids and shear bands. The present work investigates the underlying physical mechanisms during ductile f...

In recent years thanks to enhancements in design of advanced machines, laser metrology and computer control, ultra-precision machining has become increasingly important. In micromachining of metals the depth of cut is usually less than the average grain size of a polycrystalline aggregate; hence, a cutting process can occur entirely within a single...

This study is a part of the on-going research at the Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, UK on multi-scale finite-element (FE) simulations of advanced machining processes. To date this has covered conventional machining operations over multiple length scales, as well as hybrid machining techniques, n...

Purpose: The purpose of this study is to investigate the effect of anisotropy of cortical bone tissue on measurement of properties such as direction-dependent moduli and hardness. Methods: An advanced three-dimensional finite element model of microindentation was developed. Different modelling schemes were considered to account for anisotropy of...

In the last two decades, experimental observations demonstrated—and numerical simulations confirmed—that plastic deformation in the small scale, i.e. at the micron or sub-micron scales, is different from that at the macro-scale; this phenomenon is known as size effect. It was observed mostly in indentation, torsion and bending experiments, being as...

Recently, a non-conventional machining technique known as ultrasonically assisted turning (UAT) was introduced to machine modern alloys, in which low-energy, high-frequency vibration is superimposed on the movement of a cutting tool during a conventional cutting process. This novel machining technique results in a multi-fold decrease in the level o...

Several modern engineering materials are difficult to process with conventional machining methods. Ultrasonically assisted turning (UAT) is a novel machining technique, where high frequency vibration is superimposed on the cutting tool. Compared to conventional turning (CT), it demonstrated a range of benefits in processing many intractable materia...

We have studied the void growth problem by employing the Taylor-based strain gradient plasticity theories, from which we have chosen the following three, namely, the mechanism-based strain gradient (MSG) plasticity (Gao et al 1999 J. Mech. Phys. Solids 47 1239, Huang et al 2000 J. Mech. Phys. Solids 48 99–128), the Taylor-based nonlocal theory (TNT...

Several modern engineering materials are difficult to process with conventional machining methods. Ultrasonically assisted turning (UAT) is a novel machining technique, where high frequency vibration is superimposed on the cutting tool. Compared to conventional turning (CT), it demonstrated a range of benefits in processing many intractable materia...

In this paper the texture evolution in nano-indentation experiments was investigated numerically. To achieve this, a three-dimensional implicit finite-element model incorporating a strain-gradient crystal-plasticity theory was developed to represent accurately the deformation of a body-centred cubic metallic material. A hardening model was implemen...

Industrial applications of titanium alloys have grown significantly over the years primarily due to their high strength, light weight as well as good fatigue and corrosion-resistance properties. Since these alloys are hard-to-machine, there is an obvious demand to develop simulation tools in order to analyse the material's behaviour during machinin...

Owing to continuous miniaturization, many modern high-technology applications such as medical and optical devices, thermal barrier coatings, electronics, micro- and nano-electro mechanical systems (MEMS and NEMS), gems industry and semiconductors increasingly use components with sizes down to a few micrometers and even smaller. Understanding their...

A comparison of a dynamic indentation method with a quasi-static one is used to study evolution of penetration and a generated force in the indentation process. Turning (a machining process) and dynamic indentation techniques are expected to have similar ranges of strain, strain rate and stress values in the process zone of a workpiece in a case of...

A three-dimensional crystal-plasticity finite element model of nano-indentation is developed in this paper to analyze deformation of a face-centred cubic (f.c.c.) high-purity single crystal of copper. This model was implemented as a user-defined subroutine in the commercial finite element software ABAQUS/Standard and used to study cases with differe...

A comparison of a dynamic indentation method with a quasi-static one is used to study evolution of penetration and a generated force in the indentation process. Turning (a machining process) and dynamic indentation techniques are expected to have similar ranges of strain, strain rate and stress values in the process zone of a workpiece in a case of...

Industrial applications of Ti-based alloys, especially in aerospace, marine and offshore industries, have grown significantly over the years primarily due to their high strength, light weight as well as good fatigue and corrosion-resistance properties. A combination of experimental and numerical studies is necessary to predict a material behavior o...

Ti-based alloys are extensively used in aerospace and other advanced engineering fields due to their high strength and toughness, light weight, excellent corrosion resistance and ability to withstand extreme temperatures. Since these alloys are hard to machine, there is an obvious demand to develop simulation tools in order to analyse the material'...

Industrial applications of titanium alloys especially in aerospace, marine and offshore industries have grown significantly over the years primarily due to their high strength, light weight as well as good fatigue and corrosion-resistance properties. The machinability of these difficult-to-cut metallic materials with conventional turning (CT) techn...

Static indentation experiments are typically performed to characterize the mechanical properties of a material of interest by a rigid indenter of known geometry to various depths. In contrast, dynamic indentation of materials has not been fully studied. Evaluating material performance under dynamic loading conditions is a challenge and we demonstra...

Indentation experiments are extensively used to identify material properties and characterize local deformations at various length scales. In this study, we investigate the effect of repetitive indentation of a rigid indenter into a workpiece. Our aim is to obtain an in-depth understanding of the residual deformation (imprint) of the workpiece afte...

Many modern engineering materials are very difficult to process with conventional machining methods. Ultrasonically assisted turning (UAT) is an advanced technology, where high frequency vibration (frequency f≈20 kHz, amplitude a≈15 µm) is superimposed on the movement of the cutting tool. Compared to conventional turning (CT), UAT allows significan...

Implicit time integration schemes are used to obtain stable and accurate transient solutions of nonlinear problems. Methods that are unconditionally stable in linear analysis are sometimes observed to have convergence problems as in the case of solutions obtained with a trapezoidal method. On the other hand, a composite time integration method empl...

In this thesis the solution of the dynamic equilibrium equations using numerical time integration schemes are explained. The physical and mathematical backgrounds of the explicit and implicit methods are clarified and with theoretical examples both methods are compared with each other. Also using the commercial software “ADINA” three practical exam...