mohammadreza zakerzadeh

This study attempts to investigate any possible connections that might exist between noticeable tectonicactivities and changes in microbiostratigraphy on two Taleh Zang Formation successions in the Chenarehsurface and the Lab-e Safid subsurface sections. These sections are located on opposing sides of the Bala RudFault (BRF) in the Lurestan province and the Dezful Embayment. The larger benthic foraminifera (LBFs) arewidely distributed on the Taleh Zang carbonate platforms. Identifying the dominating LBF assemblages in theTaleh Zang Formation, figuring out their ages, corresponding Shallow Benthic Biozones (SBZs), and platformevolution stages in each examined sections were the investigation’s first steps. Nine different microfacies andtheir associated depositional environments were identified through analysis of vertical facies heterogeneitiesand spatial distribution of LBF assemblage alterations. These microfacies represent various sedimentaryfacies belts, including tidal flats, lagoons, foraminiferal shoals, open marine and basin environments. TheTaleh Zang platforms in the studied area, include SBZ 10, SBZ 11, and SBZ 12 which correspond to theEarly-Middle-Late Cuisian, respectively. These results are consistent with the platform evolution stage III orforaminiferal platform. Investigating the probable BRF impacts on the Taleh Zang platforms was the nextgoal. According to the changes in microbiotas, microfacies and depositional environments variations on bothsides of the BRF, considerable crushing of the LBFs, especially in MF8, which is probably due to debrisflows, the possibility of influencing the BRF on the Taleh Zang platforms within the Early Eocene in theexamined sections is not far from expected.

Today, with the advancement of robotics science and the human-robot interaction space, an approach called soft robot has been presented, which combines the principles and controls of classic robot design with soft and flexible materials. In this article, a new method for designing and modeling a pneumatic actuator for use in rehabilitation gloves based on soft robotics is proposed, and finite element modeling (FEM) is used to analyze its structure and the response of the actuator under different pressures and choosing a suitable behavior model for elastomer materials that can simulate its status under different strains. As well as, the focus is on the direct 3D printing method to make a soft actuator from thermoplastic polyurethane materials. In elastomer materials, due to the non-linearity of the relationship between stress and strain, hyper elastic behavior models are used instead of Hooke's law. In this article, based on the uniaxial tensile test results, the material has been calibrated and evaluated. In the simulation by combining different design parameters in the primary structure, the actuator has been improved in terms of bending capability and the stress and strain in the material has been reduced. Further, the range of motion (ROM) of the robotic soft glove, which allows finger flexion with assistance.

The carbonate-dominated Taleh Zang Formation is one of the exclusive formations of the Lurestan area, which was deposited in a shallow carbonate platform in the Amiran foreland basin during the Late Thanetian-Middle Cuisian and is rich in swarms of the Early Paleogene larger benthic foraminifera. Despite of short distance between the examined sections in the Rit and Daryagirveh anticlines, there are major differences in thickness, the Paleogene LBF assemblages and their ages as well as the platform evolution settings. From the Rit anticline toward the Daryageriveh anticline, thickness increases significantly and the sedimentary processes being younger.The identified SBZs and comparing the detected platform evulotion stages with the global scale, revealed that, Taleh Zang Formation can be attributed to SBZ4 and SBZ10-SBZ11, in the Rit and Daryagirveh anticlines, respectively. According this data, the Taleh Zang Formation platform evolution settings can be defined as follow; the Rit section is similar to the platform evolution stage II or coral-agal and the first larger foraminiferal platform and the Daryagirveh section resembles the platform evolution stage III or larger foraminiferal platform of the Early Paleogene low paleolatitude platforms of the Tethys. In the studied area, the reasons for the obvious age difference, microfossil assemblages, microfacies, and platform evolution settings in Taleh Zang Formation can be attributed not only to the depositional processes but also to the tectonic activities. The processes which caused obvious thickness and facies variations and record the diachronicity of the lithostratigraphic units across the basin.

Energy harvesting from wasted energy in the environment in order to run lowpower electronic devices is one of the common methods to use renewable energy. The main purpose of this technology is to provide sources of electrical energy in remote places and also to charge energy storage devices such as capacitors and batteries. The present study compares the harvested power from two electromagnetic energy harvesting systems with linear and non-linear spring (in two condition: COMSOL software and experimental results) which are vibrated by the human motion The innovation of this research is the spring that use in the energy harvesting system, which has linear spring on the one hand and is affected by non-linear spring on the other hand, as well as the validation of the simulation results using the design experimental system.

One of the common methods to resolve artery stenosis is the insertion of a shape memory alloy stent in the artery. The use of shape memory alloys in the manufacturing of self-expandable stent has expanded because of the superelastic behavior of this alloy. In this paper, we simulated a shape memory alloy stent insertion in an artery to explore stress and damage effects arising from the stent insertion on the artery by using ABAQUS software. To simulate the mechanical behavior of artery, we considered the effect of the inelastic arterial properties (stress softening and recoverable inelastic deformation) that activated under supraphysiological loading in the stenting process, and to simulate stent behavior, the Souza model is used. These two models were applied in ABAQUS by UMAT codes. By using the damage model, the amount of damage in the artery, which is one of the factors of restenosis, is investigated. Also, in this paper, we have used real diseased artery geometry, which was specified from high-resolution magnetic resonance images, therefore the analysis is more in line with reality and it is possible to determine the location of the maximum stress and damage in the artery.

In recent years demand for mobile electrical power has been increased and due to this application, energy harvester systems have been developed to convert mechanical energy into suitable electrical energy using smart materials. In this investigation, a novel arrangement of a new energy harvester using Magnetic Shape Memory Alloys (MSMAs) is developed. Elements of MSMA are attached to a corrugated beam and their roots are fixed to the base support. The reason of using the corrugated beam is to increase the stiffness of the structure in less thickness and also to increase the effective strain field in MSMA elements. This feature reduces the length of the system and the occupied volume. The way of harvesting energy from this system is based on conversion of vibrational energy to the magnetic flux gradient. That is to say; there is a number of copper coils that wrapped around the MSMA elements in a constant magnetic field. If strain or stress field is applied to the MSMA elements, some variants in specific direction are changed and as a result, the electrical current is induced to the coils. The AC voltage is produced as a result of change in magnetic flux of the surrounding coil according to Faraday’s Law. The problem is studied with simulations in Abaqus using UMAT code for modeling behaviour of MSMA elements. Also, to simulate the material properties of MSMA substance, Kiefer and Lagoudas nonlinear model is used. It will be shown the effect of various parameter on output voltage value.

In the current study, an analytical solution based on the modified couple stress theory for a nonlinear model describing the couple 3D motion of a functionally graded tapered micro-bridge is presented. The small scale effects and the nonlinearity arising from the mid-plane stretching are taken into consideration. Governing equations of motions are derived utilizing the modified couple stress theory and applying Hamilton principle. Dynamic and static analyses to determine the effects of lateral distributed forces and mid-plane stretching are investigated. To this aim, analytical Homotopy-pade technique is employed to capture the nonlinear natural frequencies in high amplitude vibrations of tapered micro-bridges with different types of geometries and material compositions. The obtained results of frequencies propose that there is a good agreement between the present analytical results and the numerical ones in opposed to well-known multiple-scale method. Furthermore, comparing the results in 2D and 3D analyses shows that in 2D analysis, the stiffness and natural frequency of the micro-beam is underestimated and it is found that increasing the tapered ratio has different impacts on natural frequencies for micro-beams with different slender ratios.

Energy harvesting is a conventional method to collect the dissipated energy of a system. In this paper, we investigate the optimal location of a piezoelectric element to harvest maximum power concerning different excitation frequencies of a vibrating cantilever beam. The cantilever beam oscillates by a concentrated sinusoidal tip force, and a piezoelectric patch is integrated on the beam to generate electrical energy. To this end, the system is modeled with analytical governing equations, then a Deep Neural Network (DNN)-based surrogate model is developed to appropriately model the system within the range of its first three natural frequencies. The surrogate model has significantly abated the computation cost. Thus, the optimization time is reduced drastically. Our investigations led to an optimal piezoelectric location for different excitation frequencies, which can result in maximum electrical output power. This location is highly dependent on the excitation frequency. When excitation frequency equals to natural frequencies, the maximum harvested power increases considerably.

In this paper, a sandwich beam of a SMP material which have a corrugated core is studied. The corrugated core is from a polymeric material. Structures with corrugated profiles show higher stiffness-to-mass ratio in the transverse to corrugation direction compared to flat structures. As a result, the beam with corrugation along the transverse direction is stiffer than the one with corrugation along the beam length. The flexural behavior of the composite corrugated beam is studied employing a developed constitutive model for SMP and the Euler-Bernoulli beam theory. The constitutive model utilized is in integral form and is discretized employing finite difference scheme. To verify the results of the Euler-Bernoulli beam theory and finite difference method, finite element models of different corrugated sections have been simulated in a 3D finite element program. The results demonstrate that the developed model for the composite beam presented in this study predicts the behavior of the beam successfully. The sandwich beam with different corrugated cores (triangular, sinusoidal and trapezoidal shapes) are compared with each other. Also, results show that the shape fixity is decreased a little, like any other reinforcing method. This decrease in shape fixity results in increase of load capacity in composite beams. The stress-free strain recovery and constrained stress-recovery cycles are both studied.

In order to use and control Shape Memory Alloy (SMA) actuators, it is essential to measure its state variables to be used as the feedback in the control loop. The wire temperature is one of critical state variables need to be fed back. However, measuring this variable is difficult and usually contains some noises and delay. Therefore, it is desirable to estimate this variable instead of measuring it. Thermoelectric model is one of the most common models used to estimate the SMA wire temperature. This model calculates the SMA wire temperature based on its input electric current. In this paper, first three unknown parameters of thermoelectric model are estimated using Extended Kalman filter (EKF) and the wire temperature is calculated based on the identified model. The parameter estimation and temperature calculation are performed on a practical SMA actuator. Then, in order to eliminate the effects of environmental disturbances and the thermoelectric model inaccuracies, the temperature is estimated using EKF. In this method, all measurable data such as the input current, the strain and stress of the SMA wire are used in the temperature estimation. The estimator combines the information obtained from both thermoelectric and Brinson models and the measurement data. This method is used for online temperature estimation of the SMA wire on a practical SMA actuator. The results show that the estimated temperature matches the actual wire temperature with high precision. Furthermore, the temperature estimation using EKF is more accurate than the estimates of the thermoelectric model.

In this work, torsional modeling and experimental characterization of a Shape Memory Alloy (SMA) rod is investigated. Experimental tests of previous studies proved that different direction of loading is effective on torque-angle response of a rod. Accordingly, using improved Brinson’s model and converting it to a torsional model and referring a twist deformation in the clockwise direction to a positive twist and a twist deformation in the counter clockwise direction to a negative twist, the asymmetry effect on the rod is investigated. Assuming a linear strain through the cross section and then finding stresses, using the asymmetric Brinson model, and integrating the stresses through the cross section the torque-angle response of the rod is presented, by using a numerical procedure. The parameters for Brinson model, including phase transformation temperatures, are derived from experimental tests and there is more than 95% agreement between the present model and experimental test. Regarding the results, a verification for the derived parameters is presented and a parametric study on SMA rod is considered. The average error of asymmetric and symmetric models with respect to the experimental tests are 5% and 15% respectively. Moreover, hysteresis inner loops are studied and asymmetric model is compared to the experimental tests. The results show good agreement of the asymmetric model when compared to experimental tests.

Many people suffering from neuromuscular diseases, have some degree of limitations in their walking pattern. Knee-Ankle-Foot Orthoses (KAFOs) help correct patients’ gait pattern by supporting knee and ankle joints. Patients with quadriceps muscle weakness suffer from some restrictions in extension as well as in controlling their flexion during the gait cycle because of abnormal stiffness pattern of the knee joint. This paper addresses patients with quadriceps muscle weakness by designing an appropriate orthosis utilizing two different mechanisms for the stance and swing phases. Stance phase mechanism locks knee joint movement from the initial-contact up to the end of mid-swing phase and with regards to the orientation of the foot after mid-stance phase, the knee joint can flex freely. The required moment to reproduce the stiffness of a normal knee joint is calculated using the OpenSim software package in conjunction with the data collected from the motion analysis of each patient.
The required moment to modify the stiffness of the knee joint for two patients with different levels of muscle weakness was reproduced using a torsional spring. By designing patient-specific orthosis, the stiffness profile of normal joint for each patient with distinct level of muscle weakness can be reproduced, allowing patients to experience smother gait cycle. Using this orthosis not only improves the patient’s gait cycle but also prevents potential damage to healthy muscles.

The hysteresis nonlinearity of the Magnetic Shape Memory Alloy (MSMA) actuator limits its control applications. To tackle the problems, usually the hysteresis behavior of these materials is models. Prandtl-Ishlinskii (PI) model is more practical in this area, because of its simplicity and having analytical inverse. Two versions of this model, entitled: rate-independent model and rate-dependent model, have been developed. Experimental results show that with increasing input frequency, the shape of hysteresis loops is amplified. In this study, by using experimental test setup the input voltage is applied to the MSMA actuator at the frequencies 0.05- 0.4 Hz and the displacement output captured by proximity position sensor, also the MSMA is modeled by generalized rate-dependent Prandtl-Ishlinskii (GRDPI) model and modified generalized rate-dependent Prandtl-Ishlinskii (MGRDPI) model. The modified version of the model are presented by the authors to enhance the ability of the GRDPI model for describing the asymmetric and saturated hysteresis behavior in MSMAs by hyperbolic tangent function in the model output. For training of the mentioned models, the actuation frequencies 0.05 and 0.2 Hz are selected and the model parameters of each model are also obtained by using genetic algorithm (GA). For validation of the models the hysteresis loop at frequency 0.1, 0.3 and 0.4 Hz is selected. The result shows that, due to using hyperbolic tangent function in the model output, the modified version of the GRDPI model can describe the hysteresis behavior in MSMAs more accurately.

Shape memory alloys (SMAs) are suitable candidates in various fields of engineering. One advantage of these alloys is their capabilities in developing high strain and force. In addition to these great features, lightweight and super-elastic behavior are other traits of these materials. These specifications are of such an importance that make SMAs to be suitably used in further engineering applications. However, their intrinsic hysteresis non-linear behavior make their usage as position actuators difficult. Despite this challenge, there are various methods proposed in the literatures to model the hysteresis behavior of such materials. In this paper, a generalized Prandtl- Ishlinskii model, because of its simplicity, efficiency and inverse analytical capability, has been used for modeling the SMA behavior. In addition, the hysteresis modeling has been validated via experimental data of one of the articles. In the control section, however, two control systems consisting PID and fuzzy sliding mode controllers have been used. Fuzzy sliding mode control system is a method that can be used in systems without mathematical model and leads to increase in their robustness. It is shown in this paper that by using this method, it is possible to apply a suitable control input to the system in order to vanish the error signal. However, by using PID controllers, the error signal is not acceptable due to the constant controller coefficients. The results indicate the more efficient performance of fuzzy sliding mode controller with respect to the classical PID controller.

Recently due to limited resources and high cost of energy, optimization of energy consumption in many aspects is under study by researchers. The main purpose of this study is to optimize a robot with DOF to find the minimum energy consumption. At first, the kinematic, inverse kinematic and dynamic analysis of the robot is performed and then the energy equations of actuators are predicted. The default path of the robot is assumed as a five order polynomial and the consumption energy of the actuators for the motion of end-effector is obtained. For optimizing the path and comparing it to the default path, two random points in the workspace of the robot are selected and then five order spline in the robot workspace is defined. In addition, the continuity conditions are satisfied and the energy consumption for the new path is predicted. Finally, the genetic algorithm toolbox of MATLAB is applied for optimization. The energy function of the actuators are defined as the objective function and the workspace of the robot set as the guess range of spline points. Finally, the optimum path with minimum actuator energy consumption is obtained.

In this paper, an innovative flexible sandwich structure is introduced which can be used in shape changing (morphing) aircrafts that adapt their external shape to different flight conditions. First, different ideas for achieving smart aircraft in the literature is briefly reviewed and then characteristics of the new deformable sandwich structure as well as its different features in comparison to other proposed structures are described. Moreover, fabrication details of deformable and load bearable sandwich panel are explained. In an aircraft with variable camber wings, deformable sections can be supposed as a cantilever beam. As a result some specimens of new deformable sandwich structure are constructed and then tested as end-loaded beams. Since the numerical study of the new proposed structure requires an understanding of the mechanical behavior of components used, a comprehensive study about the mechanical behavior of individual components of structure is conducted. According to the observation of broken samples, a distribution of cavities resulting from the manufacturing process is supposed in one type of model to obtain more accurate numerical results. Finally, another example is analyzed with the same assumptions and it is shown that in the second example, the numerical results are close to the experimental data.

In this article, the high strain rate, dynamic plastic response of materials in the standard plate impact test is numerically studied. To get the closest results to the experimental data available in the literature, different types of hardening as well as dynamic fracture models are employed. With the aid of this standard plate impact test, one can verify the new models in the ideal condition of uniaxial-strain cases. To properly model this test, to discrete the field, von-Neumann Finite-Volume method is utilized. Jonson-Cook and perfectly elastoplastic hardening models as well as the Zerilli-Armstrong model are used beside the dynamic fracture model of modified Tuler-Butcher, to predict the spall phenomenona. In this work, the impact of two plates (the flyer plate and the target plate) is analyzed. Results of the simulation is compared with the experimental data as well as the other numerical results reported in the literature. The results of the present work are in a better correspondence comparing to the experimental data. Among investigated models, employing JC constitutive model, accompanying with the modified Tuler-Butcher fracture model and Steinberg model for the elastic modulus gives the most accurate results compared to other model combinations.

Today, due to ever-increasing demand for fast and precise movements and changes, along with small-scale actuations in many engineering fields, the use and efficiency of smart materials has increased in importance. Magnetic Shape Memory Alloy (MSMA) is one of the latest smart materials having both shape memory and magnetic properties. As a matter of fact, in normal room temperatures, it has magnetic field-induced strains far more than any other smart materials such as magnetostrictive, piezoelectric or electrostrictive materials and its frequency response is greater than thermal shape memory alloy. However, on the downside, asymmetric hysteresis is a property that constrains its widespread applications. Prandtl-Ishlinskii model is one of the powerful phenomenological models for simulating asymmetric, non-linear hysteresis used to simulate smart material behavior. In the present study, MSMA hysteresis behavior simulation has been investigated through a new approach using generalized Prandtl-Ishlinskii model. After identifying the model parameters, the study compares the predicted output with the experimental results. For validation the model, using different data, model accuracy has been checked and prediction error has been compared. The experimental results have approved the capability of the model in predicting the hysteresis behavior. Thanks to invertible and simplicity potential of the generalized Prandtl-Ishlinskii model, the inverse of model can be applied as a feedforward controller for compensating the hysteresis behavior. It should also be noted that all the experimental results have been yielded through using experimental set-up.

The purpose of this paper is design, construction and the control of a two-wheel self-balancing robot. For this purpose firstly, a literature study is carried out on the history of manufactured self-balancing robots and the researches which have been done so far in this area are reported. In addition, the robot chassis with consideration of the size and material is analyzed; and the dynamic equations of the robot are computed according to the designed chassis. Then, the robot inertial parameters are measured through different experimental tests and these parameters are used in the equations. Also, the derived equations are simplified and the transfer functions are evaluated for considering the stability of the robot. In this self-balancing robot, the simplified Kalman and complementary filters are used for identifying of the bias angle from the vertical position by combination of data obtained from accelerometer and gyroscope sensors. The PID controller and the robot transfer functions are simulated in MATLAB software. Then, the controller gains are obtained for the stability of the constructed robot. These gains are computed by PID tuning toolbox of MATLAB software as well as theoretically, and the results in each method have been compared with each other. Finally, the robot control electronic circuit is designed for analyzing the results through AVR microcontroller, while angle identification sensor is used.

The scope of the current investigation incorporates the entire process involved in design and development of a Shape Memory Alloy (SMA) actuated wing intended to fulfill morphing missions. At the design step, a two Degree-of-Freedom (DOF) mechanism is designed that is appropriate for morphing wing applications. The mechanism is developed in such a way that it can undergo different two DOF, i.e. gull and sweep, so that the wing can have maneuvers that are more efficient. Smart materials commonly are selected as the actuators due to their suitable thermo-mechanical characteristics. Shape Memory Alloy (SMA) actuators are capable of providing more efficient mechanisms in comparison to the conventional actuators due to their large force/stroke generation, smaller size with high capabilities in limited spaces, and lower weight. As SMA wires have nonlinear hysteresis behavior, their modeling should be implemented in a meticulous way. In this work, after proposing a two DOF morphing wing, an aerodynamic analysis of the whole wing for unmorphed and morphed wings is presented. The results show that the performance of the morphed wing in special flight regimes is improved.