فهرست مطالب mostafa baghani

Several components of aeronautical motors and power plant stations are subjected to high temperatures, leading to creep deformation. It’s common practice to predict crack development in such components by using Continuum Damage Mechanics (CDM). Nevertheless, mesh dependency is a well-known issue in the classical CDM approach. The mesh sensitivity problem can be solved by using a nonlocal continuum approach. In the present study, in order to improve the numerical efficiency, a stress regime dependent creep model has been extended to a nonlocal model using a nonlocal theory from the literature. The nonlocal creep model was applied to a commercial finite element code, such as ABAQUS, with the help of user-defined routines (CREEP+USDFLD) to predict the load point displacement (LPD) and creep crack growth (CCG) for a compact tension (CT) specimen made of high creep strength 1CrMoV steel. A comparison between the results of the new nonlocal model and experimental data was made for verification. The mesh dependency of the new nonlocal model was investigated. The results indicate that the proposed nonlocal creep model demonstrates good mesh objectivity that was not feasible when considering the traditional local creep model.

Smart materials can react to environmental changes like living organisms and adapt themselves to environmental conditions and changes such as changes in temperature, electric current, magnetic field, light, humidity, etc. Using 3D printing to process smart materials is a new approach known as 4D printing. In this research, processing, manufacturing and 3D printing of PETG-ABS in three weight percentages of 70/30, 50/50 and 30/70 were done. The results of SEM also confirmed the compatibility of these two polymers. In all PETG-ABS mixtures, a combination of sea-island and drop-matrix morphology was observed, and for the 30/70 and 30/70 blends, phase droplets dispersed in the matrix were clearly observed. The results of mechanical properties also showed that as the percentage of ABS in the mixture increases, the tensile strength increases and the elongation decreases. The results obtained from the shape memory test indicate the existence of the ability to program the shape memory property in 4D printing mixtures. As expected, the increase in the weight percentage of ABS was associated with the disorder in the recovery of the mixtures, so the mixture with 70% by weight of PETG and 30% by weight of ABS showed the most favorable shape memory properties.

In this research, processing and 3D printing of PETG-ABS- Fe 3 O 4  nanocomposites reinforced with iron oxide nanoparticles in three different weight percentages of iron oxide nanoparticles with PETG70-ABS30 polymer matrix was done. This research was carried out with the aim of strengthening the shape memory properties, thermal properties, mechanical properties and adding the ability to indirectly stimulate the background matrix through the addition of iron oxide nanoparticles. SEM images confirmed that the mixture of PETG-ABS is immiscible and adding nanoparticles does not change the compatibility and miscibility of the base polymer, and this result is consistent with the DMTA analysis was also checked and confirmed. With increasing amount of iron oxide, the tensile strength and elongation decrease, and this decrease in mechanical properties is more pronounced in the sample of 20% by weight of iron oxide compared to the sample of 10% by weight. Nevertheless, the final strength of the samples is around 25 to 32 MPa, which indicates a suitable and acceptable distribution of nanoparticles up to 15% by weight in the polymer field. By increasing the amount of iron oxide nanoparticles, the amount of shape recovery increases and the nanocomposites containing 10, 15 and 20% by weight show shape recovery of 63.77%, 88.48 and 93.33%, respectively.

Population growth causes the need to produce more agricultural products. And the lack of water causes people to use unconventional waters, including treated sewage. Improper quality of wastewater can be harmful to the soil, plants and the health of consumers. Therefore, it is necessary to measure and check their quality.
In this study, the factors of EC, BOD, COD, TSS, TN, TP, PH, Ecoli, TC, CL,Ca, Mg, Na, SAR in effluent treatment plants, Sabzevar stabilization pond, activated sludge (Factory sanitary wastewater) and rural Wetland with Tested by standard methods. (according to 2017 version of the book Standard Methods for the Examination of Water and Wastewater) and compared with Wilcox, Ayers and Westcot, FAO, WHO, USEPA standards.To determine the competence of three different types of effluent for agricultural use.
In accordence with the standards of Iran, Wilcox, Ayers and Westcot, FAO and WHO, all three types of effluent can be used for irrigation with low to moderate negative impacts. However, in the more stringent standards (USEPA), stabilization pond and Wetland did not meet the BOD, TSS factors threshold, and the activated sludge effluent did not provide the BOD factor.
According to the results, the activated sludge treatment system meets the standards of wastewater consumption in agriculture better than the other two systems. Over time, the standards will become stricter. Choosing the type and correct operation of the treatment system has a significant impact on providing the quality standards of effluent for irrigation.

The axial turbine is one of the most important components of gas turbines in industrial and aerospace applications. As time passing the increasing of the roughness of the axial turbine blades is unavoidable. The aim of this paper is numerical investigation of the blades roughness effects on the flow field and performance of a two-stage axial gas turbine. In this research, the axial turbine is simulated three-dimensionally and the results are validated with experimental data. Then, the effects of blade roughness on flow field and performance of the turbine are investigated in five different pressure ratios. Also, in order to determine the role of stators and rotors roughness in decreasing the turbine efficiency, in a specific roughness, the first and second stators and then the corresponding rotors have been simulated separately. Numerical results show that the efficiency drop in the turbine stage is approximately equal to summation of efficiency drops when the roughness effect on the stator and rotor blades is applied, separately.

Lithium-ion batteries are the dominant energy storage tools for electric vehicles and portable devices. Their prospects depend on the development of new electrode materials. The electrode properties are highly affected by phenomena on the electrode’s surfaces. Besides experimental means, there are various simulation ways to investigate these phenomena where experiments have difficulty analyzing. However, simulating some of these events is challenging for existing simulation methods, and researchers are looking for new simulation tools to fill this gap. Here, we focus on developing and evaluating a new method for studying the key surface phenomenon inside a battery electrode in nanoscale, i.e., adsorption. In particular, we are interested in the adsorption behavior of ions on the surface of a nanosized electrode. We developed a general cellular automata model for studying the adsorption behavior of various materials, where desorption and intercalation happen during an adsorption process. The model results are compared with Freundlich isotherm and show a high resemblance. Also, an experiment concerning the lithium-ion adsorption on Titania nanotube is modeled with our C.A. model. The model is highly time-efficient and exhibits spectacular performance for simulating relatively complex systems as the results are quite close to the experimental results. As this model is general, its local rules and parameters can be modified and calibrated easily with either experiment or simulation, enabling one to study various sorption behaviors.

Modeling mechanical and thermal properties of nanocomposites is usually carried out via multi scale modeling, where the Finite Element approach is more common in homogeneous. Which can be used with identified properties of the components as a numerical approach. The use of nanoparticles significantly affects the mechanical, thermal, electrical, and mechanical strength properties. Coiled carbon nanotubes, due to their high flexibility, tolerate more strains and have recently attracted the attention of researchers. The purpose of this study is to modeling of the effective thermal conductivity of coiled carbon nanotube reinforced polyethylene nanocomposite through finite element approach. Coiled carbon nanotubes are distributed using the Monte Carlo algorithm in a uniform manner with different aspect ratios, volume fractions, and different geometries of nanoparticles in polyethylene via developing script codes. Using finite element algorithm, thermal analysis is conducted. According to the results, it is shown that increasing the volume fraction, aspect ratio, inner or outer diameter of the Coiled nanoparticles, the thermal conductivity coefficient grows, which for 0.71% volume fraction, the thermal conductivity increases by 9.35% while for the inner or outer diameter of the CCNT, has a minimal effect on the thermal conductivity of the nanocomposite by 1%. By increasing the radius of Coiled carbon nanotube from 15 to 30 nm, the thermal conductivity coefficient decrease by 2.7%.

People suffering from neuromuscular diseases, may also face certain abnormalities in their walking pattern. Drop foot patients suffer from some restrictions in dorsiflexion as well as in controlling their plantarflexion during the gait cycle because of abnormal stiffness pattern of the ankle joint. The two major complications of drop foot are slapping of the foot after heel strike (foot slap) and dragging of the toe during swing (toe drag). The current treatment options like Ankle Foot Orthosis (AFO) while offering some biomechanical benefits, do not adapt to different walking conditions and fail to eliminate significant gait complications. This study proposes a passive Ankle Foot Orthosis design which combines an AFO and torsional spring. The required moment to reproduce the stiffness of a normal ankle joint is calculated using the OpenSim software package in conjunction with the data collected from the motion analysis of each patient. Torsional spring was then used to reproduce the calculated moment for different levels of muscles weakness. It is shown that by designing patient-specific orthosis, the stiffness profile of normal joint for each patient with distinct level of muscles weakness can be reproduced.

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.

Self-healing materials are a class of smart materials that have a structurally capability to recover damage caused by environmental stimuli over time. In this paper, a semi-analytic modeling is presented for predicting the mechanical behavior of a self-healing concrete beam. Along this purpose, a continuum damage-healing constitutive model is used to investigate the effect of damage and healing in stress field of concrete pressure vessels. This model use stress spectral decomposition method to model the different behavior of concrete in tensile and compressive loadings. Also, Clausius-Duhem inequality and the thermodynamics of irreversible processes are considered and conjugate forces of damage and healing are derived for a concrete beam. Gibbs potential energy is divided into three parts; elastic energy, damage energy and healing energy. In this regard, the model introduce damage and healing surfaces to detect damage and healing behaviors from elastic one. Then, two linear isotropic hardening functions are used in these surfaces for evolving of damage and healing variables. The verification of the solution is shown by solving an example for a simply supported beam having uniformly distributed the load. Finally, a result of a self-healing concrete beam is compared to elastic one to demonstrate the capability of the proposed analytical method in simulating concrete beam behavior. The results show that for the specific geometry, the self-healing concrete beam has 21% more weight tolerate, and the deflection of the entire beam up to failure load is about 27% larger than elastic solution under ultimate elastic load.

Todays, hydrogels have attracted many researchers due to their unique properties in responding to exterior stimuli and swelling-induced by water absorption. According to their reversible swelling, it is important to predict their mechanical response. The functionally-graded temperature-sensitive hydrogel is one of the most applicable materials in industry. Thus, to study the mechanical behavior of these materials, an energy density function is introduced which includes network stretch energy and mixing part. Then, considering functionally-graded properties along the thickness, bending of FG temperature-sensitive hydrogels is solved analytically under plane-strain assumption. Verifying the presented analytical procedure, the results are compared with outcomes of finite-element-method. To solve diverse problems by finite-element-method, UHYPER subroutine has been written and verified in free-swelling problem. Next, the radius, radial stress and tangential stresses are studied by both methods for FG temperature-sensitive hydrogels. Finally, according to the importance of factors such as semi-angle and bending curvature in the industrial designs, these factors are investigated by changing the temperature in range of 320 to 288. Results demonstrate the capability of these material to be implemented in sensors and actuators. In addition, the continuity of stresses field is the other reason of utilizing FG hydrogels, while the multi-layer hydrogels do not have continuous stress fields.

The accurate and efficient design of the bilayer sensors and actuators made of hydrogels are of crucial importance. In this work, a semi-analytical method is developed to solve the swelling induced bending of hydrogel bilayer under plane strain condition. The bilayer consists of a neutral incompressible elastomer layer attached to a hydrogel layer. The interface of two layers is assumed to be perfectly bonded. Moreover, the plotted problem is simulated using Finite Element Method (FEM) employing UHYPER subroutine in ABAQUS software. Several cases are solved to demonstrate the validity and performance of the proposed semi-analytical method. A good correspondence between the presented method and the finite element method is observed. The deformation and the stresses inside the layers are presented for various material parameters employing both the developed semi-analytical formulation as well as the finite element method. Finally, the effect of density of cross-link in hydrogel polymer network on curvature is also investigated.

In recent years, shape memory alloys, specially NiTi, as a group of smart materials, have received more attentions in industrial applications. Martensitic phase transformation in shape memory alloys is the most important factor in their unique behavior. In this paper, the formation of stress induced martensite phase in the crack tip of superelastic NiTi (50.8% Ni) samples was investigated by using the DIC method. In particular, SEC specimens were subjected to fatigue mechanical loading, then the crack length and also displacement fields at the crack tip of specimens were measured by DIC technique. Control of the crack length was performed using a high magnification camera during the fatigue test. In the following, stress intensity factors were calculated according to ASTM standard E647-15. Obtained results from the fracture analysis show that fatigue threshold values are decreased with increasing the load ratio (R). In the present paper, for a load ratio of R=0.05, during the crack propagation, the fatigue threshold value is 〖∆K〗_th=17 MPa√m, while stress intensity factor is estimated about 35 MPa√m before the final failure. Also, as a new method in observation of the phase transformation, DIC pictures indicated the formation of stress induced martensite at the specimens crack tip.

According to their time and rate dependent response to the exterior loads, there was too much complexity to predict mechanical responses. Thus, a thermodynamically consistent viscoelastic-viscoplastic-viscodamage model is considered to predict their mechanical responses. Along this purpose, the explicit time-discrete form of the constitutive model is used in the finite element software ABAQUS by VUMAT subroutine. This method is valuable since its accuracy, low running time and no need of Jacobian matrix calculations. After validating ABAQUS user subroutine with experimental data obtained from creep, creep-recovery and repeated creep-recovery tests on the polymer, constitutive model sensitivity to the material parameters such as viscoelastic, viscoplastic and damage properties has been investigated. Along this purpose, it can be observed that increasing viscoplastic and damage parameters could cause rising in viscoplastic strain and damage variable. Then, the direct effects of loading time and stress level and the indirect effects of unloading time on polymer strain and damage variable were investigated in the two repeated creep-recovery tests with constant and increasing amplitudes. For instance, doubling increasing amplitude cycle number from 50 to 100 could rise service life and decrease about 75 percent of damage level.

In this paper, the effect of thermomechanical loading on the behavior of deflection-based harvested energies from a shape memory polymer system is experimentally investigated. Samples are created with honeycomb cells from poly-lactic acid using additive manufacturing techniques. The shape memory effect in shape recovery and force recovery paths are studied under thermomechanical tests in bending and tensile modes. The maximum recoverable strain energy is computed as well. According to the conducted thermomechanical tests, it is shown that the thermal expansion coefficient is much more dominant in the tensile mode. Some procedures are proposed to reduce the thermal expansion effect on the force recovery and arrive at higher energy harvested from a shape memory system.

Rutting is one of the most critical distresses influenced the asphalt pavement performance and its service life. Due to the complexity of the mechanical asphalt pavement responses, to study the mechanical behavior of this material under applying loads, a thermodynamically consistent visco- elastic visco- plastic visco- damage constitutive model has been presented in the implicit time discrete form to predict their mechanical responses within the framework pf the finite element method in software ABAQUS- Standard. It is worthy to mention that employing an implicit time discretization technique reduces the computational cost and a more stable solution is found. In this work, rutting phenomenon and prediction of the asphalt pavement service life has been investigated under three types of moving loading regimes, which forty percent of rutting difference has been obtained by comparing the pulse and equivalent loadings under moving load that would cause erroneous predictions in asphalt pavement service life.

Self-healing polymers are a class of smart materials that have attracted many researchers due to their unique ability. These materials are able to heal part of the damage without the need to identify the site. In order to study the behavior of these polymers, a thermodynamically consistent model is proposed to predict the mechanical response. Along with this, the implicit time-discrete form of the constitutive model is presented in order to utilize in ABAQUS software by UMAT subroutine. In the discretization, the Newton-Raphson method has been used to update internal variables such as viscoplastic strain components. Considering the calibration of the material parameters by the experimental results of the asphalt sample, the movement of vehicle on the desired pavement has simulated. In this research, a detailed explanation of how to perform the finite element analysis of mechanical behavior of asphalt pavements is presented using constitutive model and its implicit discretization. In the following, its validation with existing experimental results is also carried out. Next, a comparison between the simulations is performed without and with healing effect. From the results of finite element analysis, the important role of healing in the life of the pavement can be noted, which can increase the recovery of damage up to 20%.

The Axial compressor is an integrated part of a gas turbine. The central part of compressors is its blades. Blade aerodynamic has a significant effect on compressor performance. Because of the adverse pressure gradient in the compressor, any deviation in the blade profile has a significant influence on the flow field as well as the compressor performance. During the manufacturing and operation of a compressor, the blade profile may deviate from the nominal design. This deviation may happen within the manufacturing process, e.g., changing in stagger angle of the blade, changing in the maximum thickness of the blade profile or may occur in an operation process, e.g., increasing the blade surface roughness. By the way, these deviations affect the compressor performance. In this research, a numerical investigation is carried out to understand better the effects of geometry variability of the blades, including maximum thickness, blade surface roughness, and rotor blades stagger angle on the Transonic Axial compressor performance parameters, including the efficiency and pressure ratio. A CFD code, which solves the Reynolds-averaged Navier–Stokes equations, is employed to simulate the complicated 3D flow field of the axial compressor. The code is validated against experimental data for the axial compressor. The numerical result is in good agreement with the test dataand error at the design point for the efficiency was computed to be 0.3%, which shows high accuracy of the numerical method. Then, the effect of geometry variability on the axial compressor blade performance parameters is studied. Results show that increase in the surface roughness, blade thickness, and the rotor blades twist lowers the efficiency, pressure ratio and mass flow significantly in the compressor. Results show with a 10% increase of the blade installation angle at the design point, the mass flow rate decreases 1.93%, and the efficiency and pressure ratio decreases 0.35% and 1.8%, respectively. The blade surface roughness reduces the mass flow rate, total pressure ratio and efficiency of the compressor. The results show that imposing the roughness at the design point of the compressor, mass flow rate and efficiency is reduced 1.8% and 2.75 %, respectively. Meridional view of this compressor is shown in figure 1 in which the blade profiles for the first to fourth stages are DCA type [1].

Todays, hydrogels have attracted many researchers due to individual response to exterior stimuli. According to the environmental stimuli, these materials absorb a huge amount of water and swell. Due to the vast application of the functionally graded pH sensitive hydrogels, investigation of their mechanical behavior during changing of pH is very important. In this regard, the energy density is decomposed additively to energy of the network stretching, energy of mixing and energy of dissociation. Considering the variation of properties along thickness, the semi analytical solution is presented under plane strain condition. Verifying the accuracy of presented method, the result of this method is compared with the finite element method including radius, radial and tangential stresses, bending curvature and bending semi angle between pH = 2 to 8. In addition, the continuity of stresses and deformation is one of the benefits of using functionally graded hydrogel instead of multi layer ones.

In this paper, using shape memory alloy (SMA) wires, a model-based controller for force tracking of fingertips of an artificial hand finger is developed. Different aspects of modeling including static analysis, heat transfer analysis and also investigation of SMA wires, which are used as actuators, are studied. In order to parametrize the SMA wires a modified Brinson’s model is used. Brinson’s original model was not capable of accurately predicting all loading conditions thus some modifications are utilized. In order to control the applied potential difference of memory wires and consequently to control the electrical current to these wires and based on the model of shape memory wires a controller is designed. The main goal of presented controller is force controlling of a two DOF hand finger in order to grasp objects. This model contains SMA model and for compensation of system uncertainties, a proportional integrator derivative (PID) controller has been included in the closed-loop system. The effect of compensator will act only on the derivative type states and this is a new approach compared to similar literature. Simulation results of tracking a reference signal is reported which confirm that the model is in good agreement with experimental tests. The analysis of the relative tracking error for an arbitrary reference signal is 18% for the maximum normalized overshoot in experimental tests and 5% in the simulation.

Shape memory polymers (SMPs) have the ability to store the deformation and recover the original shape. Shape memory behavior is associated with two features: shape recovery and stress recovery. Full shape recovery and increase the stress recovery value are the challenges ahead of the SMPs. In this paper, the polyurethane and polycaprolactone (PCL) were blended. The thermal stimulated SMPs ware fabricated by melt mixing and solution mixing method and thermo-viscoelastic behavior of SMPs ware analyzed. Two types of polyurethanes with the same chemical structure were used as the hard phase and polycaprolactone was used as the soft phase in SMP blend. The results show that the solution mixing method has advantages such as proper appearance without defect, free from cracks and cavities, higher storage and loss modulus values without fluctuations over temperature. The blend of PCL with low hardness polyurethane one showed better shape memory behavior. In order to investigate the shape memory effect, shape recovery test was carried out with 25% pre-strain at 60°C. Also, the stress recovery was carried out by 25% pre-strain at different temperatures (60°C, 45°C and 37°C) on the samples made by solution method. The stress-recovery function was highly affected by the deformation temperature. The maximum stress and maximum recovery rate were observed in the sample with a deformation temperature of 45°C. A stent was made by the solution method and its shape recovery results showed that recovery was done completely in less than 0.5 seconds at 60°C.

In this research, using a thermomechanical constitutive model for shape memory polymers and employing the von Kármán theory, a finite element analysis of a shape memory polymer beam is presented. The importance of introducing the von Kármán theory for shape memory polymers is that the beam can have relatively high slopes during loading. Also, for optimization and designing processes we need to solve multiple problems and due to the high processing time the use of 3D model is not suitable. To validate the presented formulations, the reported results are compared with the 3D solution which was previously reported by the same authors. Accordingly, the effect of the hard segment volume on response of a thin beam has been investigated, and the results of the von Kármán beam have been reported and compared with the 3D and Euler-Bernoulli solutions. As an example, the error of the beam response in one of the solved examples is 27% for Euler-Bernoulli beam and 1% for the von Kármán solution compared to the three-dimensional solution. In general, the lower the beam thickness or the beam is longer, the Euler-Bernoulli beam error will be higher. The proposed finite element model can provide a reliable alternative response comparing to 3D modeling that requires a lot of processing time, and can be used for geometry and material parametric study.

In this paper, free vibration analysis of rotating annular disc made of functionally graded material (FGM) with variable thickness is presented. Elasticity modulus, density and thickness of the disc are assumed to vary radially according to a power low function. The natural frequencies and critical speeds of the rotating FG annular disc of variable thickness with two types of boundary conditions are obtained employing the numerical generalized differential quadrature method (GDQM). The boundary conditions considered in the analysis is the both edges clamped (C-C) and the inner edge clamped and the outer edge free (C-F).The influence of the graded index, thickness variation, geometric parameters and angular velocity on the dimensionless natural frequencies and critical speeds are demonstrated. It is shown that using a plate with a convergent thickness profile, we have a higher critical speed and natural frequency and using a divergent thickness profile, we can lower the critical speed. It is found that increase in the ratio of inner-outer radii could increase the critical speed of the FG annular disk. The results of the present work could improve the design of the rotating FG annular disk in order to avoid resonance condition

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.