آیدین غزنوی اسگوئی

The nacelle cover and nose cones of most megawatt wind turbines are made of composite sheets. Due to the complex shapes, geometries, and large dimensions of these components, they are composed of several parts that must be assembled using non-permanent mechanical joints, such as bolts. Therefore, it is very important to consider all the effective parameters that affect composite joints. One of the most critical design parameters for bolt connections is the amount of bolt preload or tightening torque. However, increasing the preload without caution is not feasible due to the composite material present on both sides of the joint, as this can potentially damage the composite sheets. As a result, this paper aims to evaluate experimentally the effect of bolt preload or tightening torque on composite joints. To achieve this, identical specimens were fabricated, each with a different bolt tightening torque ranging from 2 Nm to 50 Nm. These specimens were then subjected to a tensile load. After determining the optimal preload force, four different types of arrangements were experimentally tested to find the best bolt arrangement. Finally, by examining various aspects, the best arrangement for connecting different parts of the nacelle cover and nose cone was determined.

Due to the role of the frame, in addition to strength and fatigue analysis, the deformation of the frame is also very important. But unlike strength and fatigue analyzes, there is no specific criterion for analyzing the deformation of the main frame. Therefore, in this paper, in addition to providing a method for deriving specific criteria for evaluating the permissible deformation of the frame and the drivetrain, with the help of simultaneous simulation of the frame and the drivetrain, a solution for determining the displacements and evaluating them under loads is presented. The performance of the main frame has also been examined in terms of strength. Due to the numerical nature of the proposed way, before obtaining the results, the quality of the elements is studied from various aspects to ensure the accuracy of the results. Finally, studies have shown that the presented geometry has the necessary strength, and also has sufficient rigidity against the applied loads on the wind turbine So the drivetrain installed on it without any problems can perform its function. Finally, the main frame strength safety factor is 1.3, the deformation safety factor of yaw bearing is 1.7, and the deformation safety factor of high-speed coupling is 1.1 in both axial and radial directions. Also, the deformation analysis of the drivetrain and frame assembly shows a 15% reduction in the life of the first bearing and a 50% reduction in the life of the second bearing installed on the main shaft of the wind turbine

Passive safety is the most important part of protecting the lives of occupants in accidents and collisions when it comes to vehicle safety. The crash box is one of the most basic passive safety components in the vehicle and is expected to be able to absorb kinetic energy in longitudinal crashes in order to minimize occupant injury in safe areas. Despite the use of a variety of geometric shapes and materials in the construction of crash boxes, conical structures and aluminum have attracted much attention. In this study, aluminum and aluminum-composite conical structures were investigated. Under quasi-static loading, experimental experiments and numerical simulations showed that the addition of composite to aluminum structures could triple the specific energy absorption of the structure on average. And the use of 0 and 90 directions of glass-epoxy fibers advances the process of structural destruction step by step and cross-sectional. The result is that the folds are regular and close together, which has positive effects on specific energy absorption, mean force, and stroke efficiency of the structure.

The strength of adhesively bonded joint plays very important role on the behavior of loaded composite structures. In the present paper debonding behavior of the adhesive joint between sandwich panel and pultruded profile is investigated by the finite element method. Cohesive zone model and contact elements are used in order to simulate the adhesive joint between stiffener and the panel. Representing the adhesive material, an embedded layer is modeled between the sandwich panel and profile. The effects of geometrical parameters including the thickness of the adhesive layer and profile on the behavior of joint are investigated. Moreover, the effect of initial defect in the adhesive joint on the debonding results is studied. The results present that in the prefect bonding, increasing in the thicknesses of the profile and adhesive layer improves the joint behavior against debonding. However in defected joint, increasing the profile thickness decreases the debonding load and presence of initial defect decreases the debonding load by 51%. The results also show that presence of embedded adhesive layer has positive effect on the debonding behavior of the joint. Initial debonding load without adhesive layer decreases by 40% in comparison with the joint containing 10 mm adhesive layer.

Due to wide spread applications of adhesive T-joints in various industries، it necessitates a review of properties and strength of their fracture modes under static and dynamic loadings. By defining the ability of failure in the joint material and fracture of adhesive in the numerical model، fracture modes of sandwich T-joints have been investigated. This paper presents numerical results on the performance of sandwich T-joints subjected to static tensile and static transverse loading. The results of available experiments in the literature have been used to validate the detailed numerical models capable of simulating the damage processes observed. In general، the failure load predicted by the finite element (FE) analysis is within 5% of the experimental results.

One of the disadvantages of sandwich panels is their joints, which usually decrease the efficiency of sandwich structures. The T-joint is one the most common joint for sandwich panels. This paper deals with the numerical study of the T-joint under static loading. The results of FEM analysis are validated by the experimental results available in the literatures. In general, the failure load predicted by the FEM is in good agreementas compared with the experimental results. In the modeling of the adhesive between joint components, contact elements and cohesive zone material model are used. In addition, damage and core shear failure of the base panel are modeled by using a written macro code in the ANSYS software. Therefore, both failure modes of sandwich panel joint are investigated. In addition, the effect of the joint geometry and material of the core of sandwich panels on failure modes and failure load are studied. Finally, the results show that changing the material of the core of the sandwich panel increases the joint failure load.