A new 3D-beam finite element including non-uniform torsion with the secondary torsion moment deformation effect

In this paper, a new 3D Timoshenko linear-elastic beam finite element including warping torsion will be presented which is suitable for analysis of spatial structures consisting of constant open and hollow structural section (HSS) beams. The analogy between the 2ndorder beam theory (with axial tension) and torsion (including warping) was used for the formulation of the equations for non-uniform torsion. The secondary torsional moment deformation effect and the shear force effect are included into the local beam finite element stiffness matrix. The warping part of the first derivative of the twist angle was considered as an additional degree of freedom at the finite element nodes. This degree of freedom represents a part of the twist angle curvature caused by the bimoment. Results of the numerical experiments are discussed, compared and evaluated. The importance of the inclusion of warping in stress-deformation analyses of closed-section beams is demostrated

Piezoelectric finite beam element with FGM core for mechatronic applications

The paper deals with finite beam element with piezoelectric layers and functionally graded material of core. In the paper homogenization of FGM material properties and homogenization of core and piezoelectric layers is presented. In the process of homogenization direct integration method and multilayer method is used. The concept of transfer functions and transfer constants is used for computation of individual submatrices. Functionality of new FGM finite beam with piezoelectric layers is presented by numerical experiments. Static, harmonic and full transient piezoelectric analysis of FGM beams with piezolayers is presented

Modelling the effects of oscillating stripe cooling during a loca event in a vver440/213 reactor pressure vessel

A Loss of Coolant Accident (LOCA) is initiated by damage in the primary circuit and subsequent coolant leak of a pressurised water reactor (PWR). The loss of coolant is then compensated by the Emergency Core Cooling System (ECCS) [1]. This system supplies the primary circuit with cold high pressure coolant during emergencies. The mixing of this cold coolant results in stripe cooling of the RPV wall. This article focuses on the modelling of the mixing processes of this cooling stripe and their effects on the RPV wall in a VVER440/213 Russian type PWR. The mixing processes are modelled in a transient thermohydraulic analysis which models the mixing of the coolant flows in the reactor pressure vessel and results in the overtime temperature and pressure fields within the RPV [2]. The analysis results show that the cooling stripe is not stationary. The turbulent mixing causes an unstable oscillatory motion of the cold stripe which has a notable effect on the RPV wall temperature distribution. Selected results were subsequently transferred into a thermo-mechanical analysis via one way coupling method. This analysis was performed to evaluate the PRV loading state during the LOCA transient. Where the loading stresses were shown to correspond to the oscillatory nature of the cooling strip. In conclusion, an oscillating cooling strip can result in multiple loading cycles [3,4] of the reactor pressure vessel wall during a single LOCA transient or ECCS high pressure coolant injection

New coupled thermoelectric link finite element for FGM materials

The paper deals with derivation process of new FEM equations for steady thermoelectric two-way coupled analysis of link conductor made of Functionally Graded Material (FGM). One example of coupled analysis will be introduced to demonstrate accuracy and effectiveness of our new approach in computer modelling of such systems

Ananlysis of actuator made of fgm using new electro-thermo-mechanical finite elements

Actuator is a mechatronic system that transforms one type of energy (e.g. electric energy) into the mechanical displacement and mechanical force (mechanical energy). Nowadays, these actuators can be made of Functionally Graded Materials (FGM) to ensure simple shape of the actuator and to improve its effectiveness, particularly for micro systems. FGM is built as a mixture of two or more constituents which have almost the same geometry and dimensions. The variation of macroscopic material properties can be induced by variation of both the volume fractions and material properties (e.g. by a non-homogeneous temperature field) of the FGM constituents. The paper deals with a new approach in analysing of the systems made of FGM using our new beam finite elements. Multiphysical analysis (weak coupled electro-thermomechanical analysis) and spatial continuous variation of material properties are supported. The analysis of the micro actuator with constant cross section made of FGM is presented in the paper. This simple-shaped actuator is supplied by electric current and the efficiency of the actuator is optimised. The solution results will be compared with those obtained by using solid elements of a FEM commercial program

Modal analysis of the fgm beam-like structures with effect of the thermal axial force

The modal analysis of the FGM beam-like actuator is presented, where effects of the thermal axial force and the shear force are considered. The temperature load is assumed to be lower as the critical buckling temperature. The longitudinal variation of material properties has been assumed which can be caused by the varying constituent’s volume fraction and the temperature dependence of the constituent’s material properties. Our new FGM beam finite element has been used in the proposed analysis. An influence of the material properties variation and the thermal axial forces on the actuator eigenfrequency and eigenform has been studied and discussed

Analysis of functionally graded material actuator using new finite elements

Actuator is a mechatronic system that transforms one type of energy (e.g. electric energy) into the mechanical displacement and mechanical force (mechanical energy). Nowadays, these actuators can be made of Functionally Graded Materials (FGM) to ensure simple shape of the actuator and to improve its effectiveness, particularly for micro systems. FGM is built as a mixture of two or more constituents which have almost the same geometry and dimensions. The variation of macroscopic material properties can be induced by variation of both the volume fractions and material properties (e.g. by a non-homogeneous temperature field) of the FGM constituents. The paper deals with a new approach in analysing of the systems made of FGM using our new beam finite elements. Multiphysical analysis (weak coupled electro-thermo-mechanical analysis) and spatial continuous variation of material properties are supported. The analysis of the micro actuator with constant cross section made of FGM is presented in the paper. This simple-shaped actuator is supplied by electric current and the efficiency of the actuator is optimised. The solution results will be compared ith those obtained by using solid elements of a FEM commercial program

Analysis of PTS fracture loading of NR RPV

The article describes a multistage modelling methodology proposed by the author for the modelling of emergency core cooling processes. The methodology is based on the best practice guidelines presented by the IAEA, it is applied to a specific scenario of emergency core cooling during a loss of coolant accident[1] with an effective break diameter of 20mm. A 3D thermohydraulic analysis was performed as the first step in the solution process, where the transient changes in the pressure, velocity and temperature fields within the reactor pressure vessel were studied [2]. The primary knowledge learned when processing the results of the first step, was the presence of an oscillating cold coolant stripe in close proximity to the pressure vessel wall. The next step in the methodology consisted of a three-dimensional thermo_x0002_mechanical analysis of the reactor pressure vessel [3]. In this step, pressure thermal shock induced critical zones of mechanical loading were identified and the influence of the oscillatory character of the cold stripe on the pressure vessel was studied. The last step of the methodology consisted of a fracture mechanics analysis of postulated defects during the pressure thermal shock. Acquired results from the final step shown, that the postulated defects’ sensitivity to the oscillatory nature of the cold stripe is highly dependent on the postulated defect’s orientation

Nuclear Reactor Pressure Thermal Shock Simulation

The article describes a multistage modelling methodology proposed by the author for the modelling of emergency core cooling processes. The methodology is based on the best practice guidelines presented by the IAEA, it is applied to a specific scenario of emergency core cooling during a loss of coolant accident [1] with an effective break diameter of 20mm. A 3D thermohydraulic analysis was performed as the first step in the solution process, where the transient changes in the pressure, velocity and temperature fields within the reactor pressure vessel were studied [2]. The primary knowledge learned when processing the results of the first step, was the presence of an oscillating cold coolant stripe in close proximity to the pressure vessel wall. The next step in the methodology consisted of a threedimensional thermo-mechanical analysis of the reactor pressure vessel [3]. In this step, pressure thermal shock induced critical zones of mechanical loading were identified and the influence of the oscillatory character of the cold stripe on the pressure vessel was studied

MOR of Piezoelectric Beam FEM Model and its Control

This paper deals with the development of the FEM model of piezoelectric beam elements, where the piezoelectric layers are located on the outer surface of the beam core, which is made of functionally graded material. Subsequently, the FEM model created in this way is reduced by the so-called exact method, which is one of the MOR methods. Next MOR FEM equations are transformed into a state space model. Created state space model is connected to LQR controller and the reduced system is analysed. Developed FEM model, MOR technique, state space model and LQR control are implemented in FEM code MultiFEM