Martina Lovrenić-Jugović

The impact of the height of rotating-hearth furnace workspace on fuel consumption

Steel and iron making industries have been driven by the requirements of maintaining or improving product quality and minimization of production costs. Within these requirements the overall energy management and energy efficiency play important role. Since the rotating-hearth furnace in the seamless pipe rolling mill has the nominal heating capacity of 27 t/h, and the real needs are of an average 13 t/h, the aim of the conducted study was to investigate whether it is possible by decreasing the height of rotating-hearth furnace workspace to reduce fuel consumption. In the articles introduction, a short description of the furnace with the measured values of heating regime, which served as the basis for calculations, is given. Namely, for the purposes of calculation is necessary along the furnace to know the temperatures of flue gases and the surfaces of linings and heated charge. The intensity of the charge heating depends on the radiation heat transfer from the flue gases and the linings onto the charge and the convection heat transfer from the flue gases onto the charge. It was established with the calculations to what extent the decrease in the furnace space height affects the coefficients of heat transfer by radiation and convection, and on the other hand, the heat loss through the furnace linings on the environment. In the end of the article, the suggested solutions are explained.

Cyclic creep and recovery behaviour of glass fibre reinforced epoxy composite

This paper presents the results of an experimental and numerical investigation of the tensile behaviour of glass fibre reinforced epoxy composite for incremental and cyclic creep-recovery load conditions. The proposed constitutive model incorporates linear viscoelasticity coupled with damage and viscoplasticity for prediction of the creep-recovery responses. The material parameters are determined by fitting the experimental results. Scanning electron microscopy (SEM) of composite fracture surfaces is performed to explain the failure mechanisms. A computational algorithm for the integration of the proposed constitutive model at the material point level is derived and implemented into the finite element code ABAQUS. The model predictions are found to be in good agreement with the experimental data.

A Constitutive Model for Bovine Cortical Bone under Cyclic Creep-Recovery Loading

The present paper is concerned with an experimental research and numerical modelling of the viscoelastic-viscoplastic-damage behaviour of bovine cortical bone. A one-dimensional constitutive model is proposed to predict the experimental behaviour under creep-recovery load conditions. The material parameters are determined by fitting experimental results. The derived algorithm for the integration of the proposed constitutive model is implemented into finite element formulation. The computational algorithm shows an excellent capability to describe the tensile behaviour of bovine cortical bone for the specific mechanical conditions analyzed.

Modelling of Nonlinear Creep and Recovery Behaviour of Cortical Bone

A new one-dimensional constitutive model for human cortical bone is proposed to simulate the viscoelastic–viscoplastic behaviour occurring during creep-recovery tests.The material parameters are determined by fitting experimental results of creep-recovery tests reported in the published literature. An efficient computational algorithm for the integration of the proposed constitutive model at the material point level is derived. The derived algorithm in conjunction with the Jacobian matrix is implemented in the finite element code ABAQUS. The model predictions are found to be in good agreement with the experimental data presented in literature.

Numerical Modelling of Viscoelastic/Damage Behaviour of Cortical Bone

An efficient computational algorithm for the integration of the viscoelastic/damage constitutive model at the material point level is derived. For the presented constitutive model, material parameters, obtained experimentally for human cortical bone, are taken from literature. The derived algorithm in conjunction with the Jacobian matrix is implemented in the finite element (FE) code ABAQUS by using the user subroutine UMAT. The accuracy of the proposed algorithm is demonstrated.