Search results for "Numerical"
showing 10 items of 2002 documents
Numerical Modelling of Room Thermal Comfort Conditions
2006
Particular heat transfer coefficients of building elements gives quantitative notion only about heat losses through this building element. Analysis of the overall heat balance and heat losses of complete building and study of particular contribution of building elements in overall balance allows one to figure out the state of the building and find the building elements of bounding construction with most significant heat losses. Project variants of the buildings (or rebuilding in case of renovation), which ensure the desirable economy of energy and proportions of investments can be find varying the proportions of the surface area of building elements (e.g., windows and doors). A lot of facto…
Measuring of Geometrical Precision of Some parts Obtained by Asymmetric Incremental Forming Process After Trimming
2007
Asymmetric Incremental Forming exalts the advantages of Incremental Forming process since no dies are strictly necessary. In this way complex geometries may be manufactured with a very simple clamping equipment. On the other hand, this characteristic determines some intrinsic drawbacks which penalise its industrial suitability; first of all, the dimensional control of the manufactured part is a still open point for researchers all over the world. Several approaches have been already proposed in the last years to solve the problem, resulting only in partial solutions. At the same time, up to now, the numerical simulation did not supply significant aid to the designers, due to the problem com…
5-axes modular CNC machining center
2017
The paper presents the development of a 5-axes CNC machining center. The main goal of the machine was to provide the students a practical layout for training in advanced CAM techniques. The mechanical structure of the machine was built in a modular way by a specialized company, which also implemented the CNC controller. The authors of this paper developed the geometric and kinematic model of the CNC machining center and the post-processor, in order to use the machine in a CAM environment.
Influence of the channel design on the heat and mass exchange of induction channel furnace
2011
PurposeThe purpose of this paper is to present in‐depth numerical modelling of heat and mass exchange in industrial induction channel furnace (ICF).Design/methodology/approachThe turbulent heat and mass exchange in the melt is calculated using a three‐dimensional (3D) electromagnetic model and a 3D transient large eddy simulation method. The simulation model has been verified by flow velocity and temperature measurements, which were carried out using an industrial sized channel inductor operating with Wood's metal as a low temperature model melt.FindingsThe ICF is well‐established for melting, holding and casting in the metallurgical industry. But there are still open questions regarding th…
Numerical and experimental analysis of load capacity of pressure vessels for large deformations
1991
Abstract A method of theoretical and experimental investigations of large deformations and load capacity of pressure vessels has been proposed. Algorithms and programs for numerical analysis (with the finite element method) of spatial stress and strain state and load capacity have been worked out according to the Prandtl-Reuss theory of plastic flow. Loading in the vessel was realized in an incremental way. The loading process was continued up to the moment when the maximum loading was obtained (i.e. the moment when state of equilibrium of the vessel was not possible). It has been found that in thin-walled circular vessels with rigid bottoms, when a ratio of length to their diameter is less…
Ability of Preissmann slot scheme to simulate smooth pressurisation transient in sewers
2010
Urban drainage networks are generally designed to operate in a free-surface flow condition. However, as a consequence of heavy rainfall events or network malfunctioning, filling of sewers (pressurization) and network overflowing may occur. Several softwares are commonly used to simulate floods in drainage networks and their results are usually thought to be reliable and robust. However, no specific studies have been carried out on the behaviour of these softwares during the pressurization transient. Actually, mathematical models based on the momentum equation appear to be more suitable in correctly simulating the pressurization moving jump but models based on the energy equation are much mo…
Use of finite element models for estimating thermal performance of façade-integrated solar thermal collectors
2016
Abstract Research on building-integrated solar thermal collectors is attracting increasingly more interest. Many efforts have been focused at the design level for obtaining specific building-orientated products, but there is a significant lack of standardised methods for evaluating how the efficiency of solar collectors changes when a wall is an integral part of the solar component itself. Generally speaking, experimental tests on integrated components are not easy to realise and are, in any case, expensive in terms of time and money. Physical and numerical methods can be utilised, but at the moment, there is no common approach. The present work addresses a method for the calculation of a b…
The Transverse Crack Tension test revisited
2016
Several problems arise when measuring the mode II interlaminar fracture toughness using a Transverse Crack Tension specimen; in particular, the fracture toughness depends on the geometry of the specimen and cannot be considered a material parameter. A preliminary experimental campaign was conducted on TCTs of different sizes but no fracture toughness was measured because the TCTs failed in an unacceptable way, invalidating the tests. A comprehensive numerical and experimental investigation is conducted to identify the main causes of this behaviour and a modification of the geometry of the specimen is proposed. It is believed that the obtained results represent a significant contribution in …
Numerical studies of the melting process in the induction furnace with cold crucible
2008
PurposeAims to present recent activities in numerical modeling of cold crucible melting process.Design/methodology/approach3D numerical analysis was used for electromagnetic problem and 3D large eddy simulation (LES) method was applied for fluid flow modeling.FindingsThe comparative modeling shows, that higher H/D ratio of the melt is more efficient when total power consumption is considered, but this advantage is held back by higher heat losses through the crucible walls. Also, calculations reveal that lower frequencies, which are energetically less effective, provide better mixing of the melt.Originality/value3D electromagnetic model, which allows to take into account non‐symmetrical dist…
3D simulations and experiments of guided wave propagation in adhesively bonded multi-layered structures
2010
Understanding guided wave propagation in multi-layered plates and interaction with discontinuities can be difficult, as well as the interpretation of the ultrasonic signals. Propagation of guided waves can be studied analytically solving the equations of motion with the proper boundary conditions; nevertheless analytical models can be difficult to solve for complex multi-layered structures or having inner discontinuities. The problem can be efficiently studied using numerical techniques. Simulation of guided wave propagation in multi-layered structures, for ultrasonic waves in the MHz range, is solved here with the finite element analysis based on an explicit integration rule to solve the e…