The analytical solution of the buckling of composite truncated conical shells under combined external pressure and axial compression

M. A. Boorboor Ajdari,S. Jalili,M. Jafari,J. Zamani,M. Shariyat 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.9

The objective of this research is determining the buckling load of composite truncated conical shells under external loading by theoretical and numerical methods. The boundary conditions are assumed to be clamped. At first, basic equations and stability relations of conical shells were derived. The analysis is carried out using Donnel-type stability equations for thin cross-ply conical shells. By applying Galerkin’s method, these equations are converted to a system of ordinary time dependent differential equations. Ritz method is employed for finding the dynamic stability load. Finally, the critical static and dynamic buckling loads and the corresponding wave numbers have been found analytically. Then comparison of results is considered. Results of analytical calculations are compared with numerical results and with other researchers’ analytical results. The effects of geometric parameters, the cone semi-vertex angle, number of layers and material of fibers on buckling loads are discussed.

COMPARISON OF THE STRESS DISTRIBUTIONS OF LIQUID GAS ROAD TANKERS WITH VARIOUS CONFIGURATIONS DURING BRAKING, CORNERING, AND VERTICAL BUMP MANEUVERS

M. SHARIYAT,T. KHODABANDEH 한국자동차공학회 2013 International journal of automotive technology Vol.14 No.2

This paper compares the stress and displacement distributions of different head-shell junction configurations in LPG road tankers during different vehicle design maneuvers, such as braking, cornering, and vertical bumps, for the first time. Various combinations of heads (e.g., spherical and toroidal) and shell cross sections (circular and elliptical) are considered. The ABAQUS finite element software is used to model and analyze the fluid-filled tankers. The results show that the most critical maneuver affecting the fluid-filled tankers is cornering and the safest maneuver is braking. Moreover, the results reveal that the outer surface of the tanker generally behaves the most critically in all maneuvers, and cylindrical tankers with smaller cross-sections behave more acceptably compared to those with larger cross-sections. Among fluid-filled vehicle tankers with identical platform areas, tankers with elliptical cross-sections behave the most acceptably.

DISPLACEMENT/STRESS LEVEL-CROSSING STOCHASTIC FINITE ELEMENT-BASED ALGORITHM FOR RELIABILITY ASSESSMENT OF VEHICLE COMPONENTS WITH LOADING AND MATERIAL UNCERTAINTIES

M. SHARIYAT,M. RAJABI GHAHNAVIEH 한국자동차공학회 2012 International journal of automotive technology Vol.13 No.7

In the majority of the researches presented so far for behavior analysis of complex structures with random loading and material properties, the applications rather than the analysis algorithms have been extended. The present paper is devoted to extending the probabilistic concepts to achieve a stochastic finite element-based consistent reliability algorithm that is more consistent with the design criteria. The proposed procedure is very general and may be employes for vehcle components with complex geometries and load conditions. However, beam-type vehicle components experience simultaneous spatially-random loading conditions and material properties are employed to clarify the proposed algorithm, without loss of the generality. In this regard, important concepts such as the displacement/stress level-crossing concept are incorporated. The stress stochastic formulations are proposed in the present paper, for the first time.

MINIMIZING THE ENGINE-INDUCED HARSHNESS BASED ON THE DOE METHOD AND SENSITIVITY ANALYSIS OF THE FULL VEHICLE NVH MODEL

M. SHARIYAT,P. DJAMSHIDI 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.6

An efficient procedure for minimizing the engine-induced harshness based on NVH analysis results of a full vehicle model was developed in this study, taking stiffness and strength constraints into account. Although extensive research may be found in the literature in the field of engine support system optimization, no other studies have considered the compliances and resonances of the structure of the vehicle. In the present paper, NVH analysis results of the whole vehicle were used in an optimization procedure to suppress the transmitted vibration. A procedure was developed to minimize the transmitted accelerations to the mid-point of the driver’s seat rail. A DOE-based response surface methodology (RSM) was adopted to determine the optimal solution. Natural frequencies of the body, suspension, and other subsystems were taken into consideration in determining the optimal solution. NVH analysis was performed for two types of inputs: (a) vertical vibration due to vertical unbalanced forces and (b) torsional vibration due to oscillations in the output torque of the engine. An efficient procedure for minimizing the engine-induced harshness based on NVH analysis results of a full vehicle model was developed in this study, taking stiffness and strength constraints into account. Although extensive research may be found in the literature in the field of engine support system optimization, no other studies have considered the compliances and resonances of the structure of the vehicle. In the present paper, NVH analysis results of the whole vehicle were used in an optimization procedure to suppress the transmitted vibration. A procedure was developed to minimize the transmitted accelerations to the mid-point of the driver’s seat rail. A DOE-based response surface methodology (RSM) was adopted to determine the optimal solution. Natural frequencies of the body, suspension, and other subsystems were taken into consideration in determining the optimal solution. NVH analysis was performed for two types of inputs: (a) vertical vibration due to vertical unbalanced forces and (b) torsional vibration due to oscillations in the output torque of the engine.

Experimental and numerical investigation of composite conical shells’ stability subjected to dynamic loading

Sina Jalili,Jamal Zamani,M. Shariyat,N. Jalili,M.A.B. Ajdari,M. Jafari 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.5

In this article, stability of composite conical shells subjected to dynamic external pressure is investigated by numerical and experimental methods. In experimental tests, cross-ply glass woven fabrics were selected for manufacturing of specimens. Hand-layup method was employed for fabricating the glassepoxy composite shells. A test-setup that includes pressure vessel and data acquisition system was designed. Also, numerical analyses are performed. In these analyses, effect of actual geometrical imperfections of experimental specimens on the numerical results is investigated. For introducing the imperfections to the numerical models, linear eigen-value buckling analyses were employed. The buckling modes are multiplied by very small numbers that are derived from measurement of actual specimens. Finally, results are compared together while a good agreement between results of imperfect numerical analyses and experimental tests is observed.

Experimental and numerical investigation of composite conical shells' stability subjected to dynamic loading

Jalili, Sina,Zamani, Jamal,Shariyat, M.,Jalili, N.,Ajdari, M.A.B.,Jafari, M. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.5

In this article, stability of composite conical shells subjected to dynamic external pressure is investigated by numerical and experimental methods. In experimental tests, cross-ply glass woven fabrics were selected for manufacturing of specimens. Hand-layup method was employed for fabricating the glass-epoxy composite shells. A test-setup that includes pressure vessel and data acquisition system was designed. Also, numerical analyses are performed. In these analyses, effect of actual geometrical imperfections of experimental specimens on the numerical results is investigated. For introducing the imperfections to the numerical models, linear eigen-value buckling analyses were employed. The buckling modes are multiplied by very small numbers that are derived from measurement of actual specimens. Finally, results are compared together while a good agreement between results of imperfect numerical analyses and experimental tests is observed.