Multiaxial ratcheting evaluation of functionally graded cylindrical shell by means of Ohno–Wang’s type models

In the present paper, the ratcheting responses of functionally graded (FG) pipe by means of nonlinear kinematic hardening rules of the Ohno–Wang (O–W), McDowell, Jiang–Sehitoglu (J–S) and Chen–Jiao–Kim (C–J–K) models are investigated. The FG pipe is considered to be subjected to a broad class of non-proportional/proportional with different loading types including tension–torsion, tension/thermal–internal pressure with different loading sequences and directions. In the current constitutive models of FG pipe, not only the physical and mechanical properties are variables but also the coefficients of the kinematic hardening rules vary as a power law through thickness. An implicit integration scheme implemented within user subroutine UMAT in ABAQUS/standard is presented for the relatively complicated constitutive models. Comparing with the novel experiments and available results in the literature, the predicted results by the proposed numerical method are demonstrated to be reliable. Results reveal the significant influences of the adopted hardening rules incorporated in the constitutive model and also FG inhomogeneity constant on the multiaxial ratcheting responses of FG pipe.

     

Thermo-elastic analysis of a functionally graded piezoelectric rotating hollow cylindrical shell subjected to dynamic loads

In this study, dynamo-thermo-elastic analysis of a rotating piezoelectric hollow cylinder made of functionally material is presented. Coupled differential quadrature and finite difference methods are used to solve boundary/initial value equations of the problem. Material properties are assumed to be graded in radial direction and temperature independent. Numerical results obtained and convergence are studied, and then verified with reported results in literature. Effect of variations of the grading parameter, angular velocity, thermal gradient and ratio of the outer to inner radii on the stresses, radial displacement and electrical potential are presented.     

Influence of pumpkin puree and guar gum on the bioactive,rheological, thermal and sensory properties of ice cream

The effects of pumpkin puree and guar gum on the bioactive, rheological, thermal and sensory properties of ice cream were investigated. The addition of pumpkin puree increased total phenolic content, dietary fibre, and antioxidant activity. Appropriate models described shear thinning and thixotropic behaviours of all mixes. By either adding pumpkin puree or by increasing guar gum concentration, all rheological properties increased except the flow behaviour index. Adding pumpkin puree reduced the freezing point temperature, ice content, frozen water and glass transition temperature but it increased unfreezable water. Increasing guar gum concentration did not alter colour and firmness, whereas the pumpkin puree increased colour, intensity of fruit flavours and firmness.     

Effect of Heat Treatment on the Properties of AlCu26Si8

ABSTRACT

In this paper, in situ centrifugal casting was proposed to fabricate Al-26 wt.% Cu-7.8 wt.% Si FG pipe with the density of 3.5 g/cm³ and also the wear resistance of 0.0241g/mm². The casting mould is preheated to approximately 200°C to avoid chilling effects, segregation, porosity and compensation of the shrinkage of the alloy during the casting. The microstructure results show that the Al₂Cu content smoothly decreases from the outer layer to inner layer. Vickers hardness, coefficient of thermal expansion (CTE) and mechanical properties of the present FG pipe are measured to show the significant dependence of the microstructure. Furthermore, the heat treatment of the samples are conducted in boiling water (100°C) for 4.5 h to promote the formations of new Al₂Cu particles into the α–Al phase and consequently improve the hardness and CTE of the FG pipe.