Ali Pourkamali Anaraki

Shahid Rajaee University | SRTTU · Department of Solid Mechanics

Purpose: In this work, the influences of different field operating parameters (pH and partial pressure of H 2 S) and crack types (isolated and cluster cracks) are investigated on the distribution of hydrogen concentration in pipeline steel. Design/methodology/approach: A numerical simulation based on the finite element method was performed using th...

As a measuring device, an auxetic piezo-resistant sensor must have the characteristics of the measuring equipment. One of these features is to have the correct and same answer in different strains and directions (same answer in different conditions). This issue should be considered in the case of auxetic piezo-resistant sensors because of having di...

Stents possess disadvantages such as foreshortening and dogboning. Material selection alongside topological modifications are two main approaches to overcome these issues. Stents with negative Poisson’s ratio, also known as auxetic property, can lead to promising performance improvement. Therefore, in this study, three stents were designed by impro...

The behavior of Auxetic structures is highly dependent on the geometric parameters of the unit cell. To achieve the desired behavior, it is necessary to perform a parametric study on the unit cell. A conventional parametric study (which includes modeling and analysis with different parameters) is very time consuming and error prone. The Auxetica pl...

Due to various benefits such as unlimited degrees of freedom, environment adaptability, and safety for humans, engineers have used soft materials with hyperelastic behavior in various industrial, medical, rescue, and other sectors. One of the applications of these materials in the fabrication of bending soft actuators (SA) is that they have elimina...

In this paper, the fracture behavior and micro-damage evolution in DP600 and DP980 steels were studied using experimental and numerical methods. First, four specimens with different loading conditions were tested to investigate the influence of the stress state on the fracture behavior and in-situ tensile tests were carried out in order to evaluate...

In this paper, the modified SIMP topology optimization (TO) method was used, to introduce diverse auxetic unit cells with different volume fractions, composing of the symmetric, chiral and re-entrant unit cells. The output results suggested that the geometry of the 2D auxetic structures were extremely dependent on the values of SIMP method paramete...

Porous materials especially closed-cell metallic foams play important roles among novel materials because of their good characteristics e.g. high strength to weight ratio and crashworthiness. On the other hand, mechanical behavior determination and detailed characterization are essential in efficient manipulation and material tailoring. In the pres...

Auxetic materials are a family of rationally designed artificial structures that have unique effective properties gained from the distribution of the internal architecture rather than of the chemical composition. This article used the modified solid isotropic material with penalization method for topology optimization of 2D re-entrant auxetic struc...

The electro-mechanical impedance method identified as a suitable method for structural health monitoring and damage detection in structures, which is considered as a non-destructive inspection method. Piezoelectric smart materials are used as sensor/actuator to excite the structure and is installed on the structure, which has the task of identifyin...

In high cycle fatigue, damage and plasticity occur at the microscale, a scale smaller than the representative volume element (mesoscale). Therefore, the two-scale damage model is used for fatigue life assessment. In this model, a spherical inclusion is assumed to be fully embedded in the matrix. However, experimental observations show that the micr...

Multi-Walled Carbon nanotubes (MWCNT) coupled with Silicone Rubber (SR) can represent applicable strain sensors with accessible materials, which result in good stretchability and great sensitivity. Employing these materials and given the fact that the combination of these two has been addressed in few studies, this study is trying to represent a lo...

The effect of hydrogen on the microdamage evolution of 1200M advanced high-strength steel was evaluated by the combination of experimental and numerical approaches. In the experimental section, the tensile test was performed under different testing conditions, i.e., vacuum, in-situ hydrogen plasma charging (IHPC), ex-situ electrochemical hydrogen c...

An auxetic structure as a substrate material in sensor applications improves sensitivity performance due to lateral expansion under tensile loading. The presented stretchable, highly sensitive at-low-strain piezoresistive sensor was manufactured by mixing the silicone rubber and chopped carbon fibers in an auxetic re-entrant structure form. Auxetic...

Fall drop impact test for closed-cell aluminum foams were conducted experimentally and numerically. Deformation mechanisms at the cell level were discussed. The deformation mechanisms of cells were investigated and a novel FE model was proposed. Our model is combination of cellular part in the middle and solid part with the mechanical property of t...

The electro-mechanical impedance (EMI) method has been accepted as an effective technique for detecting damages in the Structural health monitoring (SHM). EMI at any point of the structure depends on material properties, geometry and boundary conditions that all appears in dynamic stiffness of the structure. In spite of the expensive experimental m...

The prediction of residual stress relaxation is essential to assess the safety of welded components. This paper aims to study the influence of various effective parameters on residual stress relaxation under cyclic loading. In this regard, a 3D finite element modeling is performed to determine the residual stress in welded aluminum plates. The accu...

In this study, 2D triangular anti-trichiral structures and auxetic stents, under compression, were introduced. The cores of the anti-trichiral structures were the equilateral triangles. The deformation mechanisms in 2D structures were based on the rotation of the triangles and bending of the ligaments. A parametric study was carried out to investig...

Foam filled tubes (FFT) are novel structures with high energy absorption, enhanced strength to weight ratio, and tailoring capability. In the present paper, we have analyzed quasi-static uniaxial compression and low-velocity impact behavior of FFT with closed-cell metallic foam cores and functionally graded densities both experimentally and numeric...

The effect of hydrogen on the mechanical properties of X70 pipeline steel was investigated by a combination of macro- and microscale approaches. Various tensile tests under vacuum, in-situ H-plasma charging (IHPC), and ex-situ electrochemical H-charging (EEHC) conditions were conducted to elucidate the hydrogen effect in the macroscale approach. Al...

The evaluation of residual stress and its redistribution under cyclic loads are crucial to guarantee the integrity of welded components. In this paper, the effective parameters on welding residual stress relaxation are examined in thin cylindrical vessels due to cyclic pressure. First, the 3D finite element modeling is performed to evaluate the wel...

Erosion of components working in particulate environment is a serious problem that causes premature failure. In this study, we want to identify different areas caused by particle impact erosion and also express a permanent impression using experimental method. Our study was performed on the real turbine blade worked in the industry. This paper inve...

Tuning the electromechanical performance in piezoresistive composite strain sensors is primarily attained through appropriately employing the materials system and the fabrication process. High sensitivity along with flexibility in the strain sensing devices needs to be met according to the application (e.g. human motion detection, health and sports...

Heat source modeling is one of the most important problems in welding simulation and has a significant impact on temperature and residual stress fields. This paper first investigates accuracy of surface and volumetric heat fluxes for predicting temperature of the gas tungsten arc welding of aluminum plates, through the 3D finite element analysis. C...

Micromechanical behavior of two dual-phase steels is investigated using experimental and numerical methods. Experimental data for 2 dual phase steel specimens (SP1 and SP2) is obtained from the literature and is used to create 2D representative volume elements (RVEs) based on the continuum mechanics framework. Interphase of the specimens is incorpo...

Planetary gears are used extensively in power transmission systems with high torque to weight ratio and reducing the speed in less space and have access to deceleration in several stages. The main objective of this research is to create a general understanding on the dynamics and vibrations of the planetary gear systems and provide a general review...

Gyroscopic effects may change the stability, dynamic behavior and vibratory responses of the systems at high-speed applications in a significant manner. In this study a new linear time-invariant, LTI, lumped mass model in three-dimensional space is developed with a high emphasis on gyroscopic effects for a double-helical planetary gear system. In t...

ABSTRACT High-speed planetary gears, or more generally, gyroscopic systems do not preserve energy and therefore subjected to instability. In this research, the dynamic equations for a double- helical planetary gear system in 3-D space considering six degrees of freedom for each member are extracted. Then, the stability of the system in the critica...

In this research a linear time- invariant lumped mass model, LTI, in three-dimensional space for a double- helical gear pair is developed and effects of gyroscopic moment on the dynamics and vibrations are studied. In this model, each member has six degrees of freedom and both of the mesh stiffness and bearing stiffness are undertaken. The dynamic...

Strain sensing in applications such as soft robotic, human motion detection, health and sports monitoring, mass measurement, human-machine interfaces has attracted increasing attention. In the present paper, a piezoresistive composite strain sensor based on chopped carbon fiber (CCF) as a conductive element and silicone rubber as a stretchable poly...

In this study, some new 2D auxetic metamaterials were investigated and called octagonal auxetic metamaterials. The structures were examined by numerical and experimental approaches and 3D printing additive manufacturing technique was employed to fabricate the structures from thermoplastic polyurethane elastomer (TPU) which is considered as a hypere...

Gyroscopic effects may change the stability, dynamic behaviour and vibratory responses of the systems at high-speed applications in a significant manner. In this study, a new linear time-invariant lumped mass model in three-dimensional space is developed with a high emphasis on gyroscopic effects for a double-helical planetary gear system. In the d...

In this research, the fracture phenomenon was investigated on flexible roll forming process of channel section using ductile fracture criteria and forming limit diagram (FLD) by considering the effect of anisotropy. For this purpose, a finite element simulation of the process using the ABAQUS software was done. The fracture in this process was eval...

Dual phase (DP) steels, which have an intricate microstructure, consist of ferrite and martensite phases and because of interaction between the ferrite and martensite phases, those have complex behaviors. In this study, the flow curves of two heat-treated DP steels, DP800 and DP980, were compared with those of the 2D and 3D micromechanical models b...

A novel method to model the interphase between phases in DP steels is introduced and implemented on a specimen created from DP980. Use of the proposed method remedied the problem of underestimation of stress-strain curve by 2D RVEs and also showed that failure initiates at the interphase between phases.

Simulated annealing which has been recently used in engineering applications is one of the most popular metaheuristic algorithms to solve optimization problems. In this work, an adaptive simulated annealing (SA) technique coupled with an adaptive finite element method is proposed and developed to optimize bilayer composite sheet hydroforming proces...

An adaptive hybrid simulated annealing technique with ANSYS parametric design language is developed to optimize hydrodynamic deep drawing assisted by radial pressure process. This work aims to determine an optimal pressure path by redefinition of simulated annealing parameters and creating an adaptive finite element code using ANSYS parametric desi...

Here, the effect of fiber metal laminate (FMLs) patches was studied for repairing of single-sided cracked aluminum plates experimentally to see their response to Charpy impact tests. The main desired parameters were composite patch lay-up, crack length, and crack angle each one in three levels. All experimental attempts generated and followed based...

Fiber metal laminates (FMLs) are widely used in aerospace industries nowadays. Reparation of the cracks in these advanced materials was first done by some aeronautical laboratories in the early 1970s. In this study, experimental investigations were done on the effects of repairing the edge-cracked aluminum plates using the FML patches. The repairin...

Since the advent of additive manufacturing techniques, regular porous biomaterials have emerged as promising candidates for tissue engineering scaffolds owing to their controllable pore architecture and feasibility in producing scaffolds from a variety of biomaterials. The architecture of scaffolds could be designed to achieve similar mechanical pr...

In many industrial applications, we deal with the impact of micron-scale particles onto a target surface. So, a large number of studies have been conducted to perceive damage mechanism and identify effective parameters of this phenomenon at micron scale. In all of these studies, target surface has been considered as ideally smooth. However, it is v...

In many industrial conditions, we deal with impact of particles on a surface that can cause premature failure. A series of studies have been conducted to investigate the effect of parameters on this phenomenon on smooth surfaces at micron-scale. But there is no ideally smooth surface at this micron level. Our study investigated the effect of partic...

Purpose – The purpose of this paper is to use the fiber metal laminates (FML) composites as a patch for repairing a single notched specimen made of AL1035 aluminum alloy. The FML composite patch was bonded on one side of the cracked specimens by adhesive Araldite 2015. Then the fatigue crack growth tests were conducted on the specimens and the effe...

The development of high performance coatings for the protection against erosion requires understanding of their complex failure mechanisms occurring during solid particle impact. In the present work, a numerical analysis is carried out to study the effect of particle diameter, particle velocity, and coating thickness on erosion damage of gas turbin...

In this paper, Charpy impact tests were conducted on cracked aluminum plates repaired with FML composite patches. The effects of the crack characteristics and patch lay-up sequence on the energy absorption of the specimens were investigated experimentally. In order to reduce the test numbers, the design of experiments method was used, and the resul...

Dual phase (DP) steels have a microstructure consisting of a ferrite matrix, in which particles of martensite are dispersed. In this work both experimental and numerical methods were employed to investigate the mechanism of failure in DOCOL 600 DP steel. The tensile test for specimens was interrupted in different steps, to capture the mechanism...

Fiber metal laminates (FMLs) are widely used in aerospace industries nowadays. Repairing of the cracks in these advanced materials was first done by some aeronautical laboratories in early 1970s. In this study, experimental investigations were done on the effect of repairing the center-cracked aluminum plates using the FML patches. The repairing pr...

Fiber Metal Laminates (FMLs) are widely used in aerospace industries nowadays. In this study, numerical investigations of adhesively bonded FML composite patch repairs of cracked aluminum panels is reported. Pre-cracked 3035 Aluminum panels of 179×76×1.5 mm repaired with rectangular single sided FML patch were used as test specimen. The finite elem...