a b s t r a c tNatural ventilation performance of a two-sided wind-catcher is investigated for various wind angles (a ¼ 0 e90 ) and wind speeds by experimental wind tunnel and smoke flow visualization. A 1:50 scale model of a real wind-catcher in the city of Yazd (Iran) is employed. The pressure coefficient as well as velocity are measured by pressure taps and hot-wire anemometer, respectively. The hot-wire results are used to evaluate the induced airflow rate and turbulence intensity. Smoke flow visualization techniques are employed to study the flow structure and patterns inside and outside of the wind-catcher. The results indicate that the wind direction has a large influence on the wind-catcher performance and the induced airflow rate increases with increasing the wind speed. The hot-wire results show that the transition angles of the house window and windward opening for all wind speeds occur at the wind angles of 39 and 55 , respectively. An excellent agreement is also found for these transition angles when they are determined by measured pressure coefficients. Based on measured quantities, it is found that the windcatcher acts as a chimney for the wind angle larger than the windward transition angle (a ¼ 55 ) and the highest ventilation rate occurs at the wind angle of 90 .

In this study, static response of cylindrical sandwich panels with flexible core based on the high-order theory (HOT) of sandwich structures is investigated. A layerwise formulation is developed to study the applicability of HOT. The face sheets are considered as composite laminates with cross-ply layup that follow first-order shear deformation assumption and the core is considered as a linear elastic medium with out-of-plane stresses only. The field equations along with the boundary conditions are derived by means of the principle of minimum potential energy. A closed-form solution is developed for simply supported boundary conditions and a comparison is made with results from the commercial finite element software ANSYS to verify high-order and layerwise solution results. Finally, influence of parameters including the core to face sheets stiffness ratio and the core to face sheets thickness ratio on the applicability of HOT is investigated. Results demonstrate a good agreement between high-order and layerwise results for the small thickness ratio of the core to the face sheet and low stiffness cores.

In the present study, vibration and damping analysis of cylindrical sandwich panels containing a viscoelastic flexible core based on the high-order theory of sandwich structures is investigated. A layerwise formulation is developed to study the applicability of the high-order theory. The face sheets are considered as composite laminates with cross-ply layup that follow first-order shear deformation assumption and the core is considered as a linear viscoelastic medium with out-of-plane stresses only. The field equations along with the boundary conditions are derived via the application of Hamilton’s principle. A closed-form solution is developed for simply supported boundary conditions and a comparison is made with available results in the literature to verify the high-order and layerwise solution results. Finally, the influence of parameters including the core stiffness, the core to the face sheets thickness ratio, and the core damping on the applicability of the high-order theory, and variation of natural frequencies and modal loss factors of the sandwich panel are investigated. The results demonstrate a good agreement between the high-order and layerwise theories for small core stiffnesses, and for a wide range of the core to the face sheet thickness ratio and core damping.

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This study represents an effort to predict the bearing strength, failure modes, and failure load of bolted joints in foam-core sandwich composites. The studied joints have been used in a light full composite airplane. By using solid laminates, a new design for the joint zone is developed. These solid laminates include a number of glass plies with total thickness equal to core thickness. The effect of solid laminate size and interface angle of foam-solid laminate in the bonding zone on the bearing strength, failure loads and type of modes are investigated. The numerical study is performed using 3D FEM in ANSYS commercial code. Tsai-Wu failure criterion is used in the failure analysis. The results indicate that the most important parameter in the proposed joint zone design is the foam-solid laminate interface angle which plays an important role on the value of failure criterion (damage) in the bonding zone. Also, the use of squared shaped solid laminate as compared with a circular laminate will decrease the criterion value significantly. Finally, the influence of solid laminate size and interface angle on the buckling strength was discussed. As obtained through eigenvalue buckling analysis, the increase of solid laminate size or interface angle could result in considerable higher buckling strength.

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