Amal E. Alshorbagy

Finite Element Analysis of the Deformation of Functionally Graded Plates under Thermomechanical Loads

The first-order shear deformation plate model, accounting for the exact neutral plane position, is exploited to investigate the uncoupled thermomechanical behavior of functionally graded (FG) plates. Functionally graded materials are mainly constructed to operate in high temperature environments. Also, FG plates are used in many applications (such as mechanical, electrical, and magnetic), where an amount of heat may be generated into the FG plate whenever other forms of energy (electrical, magnetic, etc.) are converted into thermal energy. Several simulations are performed to study the behavior of FG plates, subjected to thermomechanical loadings, and focus the attention on the effect of the heat source intensity. Most of the previous studies have considered the midplane neutral one, while the actual position of neutral plane for functionally graded plates is shifted and should be firstly determined. A comparative study is performed to illustrate the effect of considering the neutral plane position. The volume fraction of the two constituent materials of the FG plate is varied smoothly and continuously, as a continuous power function of the material position, along the thickness of the plate.

Mechanical performance of intraply and inter-intraply hybrid composites based on e-glass and polypropylene unidirectional fibers

The aims of this study are to design, fabricate and investigate the mechanical properties of new hybrid composite laminates made from polypropylene-glass unidirectional fibers and epoxy matrix. Specimens were fabricated following the hand lay-up technique in intraply and inter-intraply configurations. Results are presented regarding the tensile, flexural, in-plane shear and interlaminar shear behaviors of fabricated composites with particular consideration of the effects of the plies stacking sequence and hybrid configuration. The experimental results reveal that the mechanical properties of polypropylene/epoxy composite can be effectively improved by the incorporation of glass fiber through the formation of either intraply or inter-intraply hybrid composites. With a proper choice of the hybrid configuration and the plies stacking sequence, the fabricated hybrid composites achieved property profiles close to those of homogeneous glass reinforced laminate in terms of specific properties. Resistance of the intraply hybrid composite to tensile and flexural loadings is higher than inter-intraply hybrid composites. On the other hand, the highest in-plane and interlaminar shear strengths are associated with the inter-intraply hybrid composite with glass fiber core. Additionally, an analytical analysis was also introduced to provide a good correlation with the experimental data, which give an insight on the ideal plies stacking sequence to achieve the required properties.

3-D Finite Element Analysis of Transient Heat Transfer and Thermal Stress in a Crowned Mandibular First Molar Tooth

A three-dimensional transient thermoelastic finite element model was developed to simulate a crowned mandibular first molar tooth under thermal loading as a result of hot liquid intake in the mouth. The effect of crown materials and cement types on thermal stress distribution in a crowned tooth was studied. A single layer crown (Empress) and a double layer crown (In-Ceram) were used as model materials, representing the two extremes in strength of contemporary materials compared to porcelain fused to metal crowns. Resin, glass ionomer, and zinc phosphate cements were evaluated, representing the upper and lower limits of modulus of elasticity currently available. The temperature changes as a result of hot liquid intake were calculated. Then, the thermal stress distributions due to the temperature changes were obtained. The hot liquid was of temperature 60 degC in all prepared cases. The distribution of temperature and stress were plotted and analyzed for all cases. A comparison between different cases was made to achieve the most suitable crown and cement materials