Using Y molecular sieve as the core, Y/SBA-15 composite molecular sieves were prepared by different crystallization methods in the paper. The growth process and morphologies of the composite molecular sieves were controlled by adjusting the synthesis factors. The structures and acidity of two kinds of composite molecular sieves were characterized by X-ray diffraction (XRD), N2 adsorption/desorp...

A numerical procedure for the design of impact damage resistant composite laminated structures is proposed in the present paper. This procedure, based on probabilistic analyses, is able to support the design of complex composite laminated structures by accounting for the scatter in composite materials’ mechanical properties (related to the mutable environmental conditions experienced by an airc...

Free vibration behavior of laminated composite plates stiffened by different lattice structures is considered. To simulate free vibration, finite element models were created with Ansys Parametric Design Language (APDL). In the models, SHELL181 and BEAM181 elements used to model structures, respectively. The influence stiffeners on natural frequencies plate examined for clamped-free-clamped-free...

Motorcycles are considered a cost-effective and major means of transportation, particularly in the developing countries. However, motorcyclists are at higher risk of head and brain injuries in road crashes, which is the primarily cause of most of the fatalities occurred. Wearing a protective helmet is an efficient way for the safety of the motorcyclist, since it reduces the severity of head inj...

In this study, the behavior of a composite lattice cylindrical shell is investigated in the buckling deforming. Also, the distribution of shell buckling response and the stress field is studied after making some defects on the ribs.Therefore using ANSYS software, a 3D finite element model of the shell has been created for the analysis. Material properties and geometrical data of the shell are o...

A new closed form formulation of three-dimensional (3-D) refined higher-order shell theory (RHOST) to analyze the free vibration of composite circular cylindrical shells has been presented in this article. The shell is considered to be laminated with orthotropic layers and simply supported boundary conditions. The proposed theory is used to investigate the effects of the in-plane and rotary ine...