Search results for "CERAMICS"
showing 10 items of 1599 documents
Part program automatic check for three axis CNC machines
2001
Abstract The simulation and verification of NC codes for CNC machining is a very important task. The aim of this work is to limit the number of cutting tests needed to verify the right writing of the part program for a CN milling machine in the intent of saving time, human resources and money. This is obtained through the Boolean operation among solids, in AutoCAD environment, of the volume covered by the tool during the operations ruled by the part program.
Finite element modelling of temperature distribution in the cutting zone in turning processes with differently coated tools
2005
Abstract The aim of this study is to check the applicability of various simulation models to obtain finite element solutions of cutting forces, specific cutting energy and adequate temperatures for a range of coated tool materials and defined cutting conditions. Commercial explicit finite element code Thirdwave AdvantEdge has been used in simulations of orthogonal cutting processes performed by means of uncoated carbide and coated tools. The latter were equipped with progressively increasing number of thin layers including TiC, TiN and Al 2 O 3 films deposited onto ISO P20 carbide substrates. Results showing the tool–chip interfacial friction influencing the temperature distribution fields,…
Advanced models for smart multilayered plates based on Reissner Mixed Variational Theorem
2017
In the present work, families of equivalent singe layer and layer-wise models for the static and free vibrations analysis of magneto-electro-elastic multilayered plates are developed. The models are defined in the framework of a unified formulation, which offers a systematic approach for generating refined plate theories through suitable expansions of the through-the-thickness components of the relevant fields, considering the expansion order as a free parameter. The key features of the developed formulation are: a) the condensation of the electric and magnetic description into the mechanical representation, based on the quasi-static electric-magnetic approximation, which allows to reduce t…
A comparative evaluation of crashworthy composite sandwich structures
2007
Abstract This paper describes an experimental evaluation of the energy absorption properties of a series of novel designs for cost-effective crashworthy composite sandwich structures. All the designs are based on the concept of the “tied-core” sandwich, i.e. the use of additional core reinforcements that act to tie the opposing facings of a sandwich together, thus preventing catastrophic failure under edgewise loading. The design, manufacture and crush testing of hollow rectangular tubes fabricated from six different tied-core concepts is described. Factors that are shown to promote high energy absorption include large, continuous areas of contact between the facings and the ties, non-thin …
Design and optimization of bonded patch repairs of laminated composite structures
2015
International audience; The present study proposes a method for design optimization of external patched repairs. The tensile behavior of notched specimens with patched repair was studied using finite element analysis and compared with experimental results. It was found that high stress concentrations along the transverse edges of circular patches and/or at the longitudinal edges of the hole leads to early damage initiation in the parent plate. The damage initiation site and its propagation depend on the patch in-plane stiffness. The optimal patch design can be characterized by a strength ratio R*. The overall design of the patch repair can be considered using a dimensionless design paramete…
An analytical model for improving precision in single point incremental forming
2007
Abstract In the modern manufacturing scenario and, in particular, in sheet metal forming, the requirement of customised production is still growing. The introduction of incremental forming enables the production of customised components in small lots. In particular, single point incremental forming is characterised by the simplest equipment; any die, in fact, is avoided reducing the necessary tooling to a simple frame, able to clamp the sheet, and a hemispherical punch that imposes the required deformation. This tooling simplicity and the associated process mechanics, in turn, determine a sometimes relevant lack of accuracy. The paper is focused on the investigation of the influence of the …
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 …
Innovative sheet metal forming processes: numerical simulations and experimental tests
2004
Abstract In this paper, computer aided engineering of some innovative sheet metal forming processes is reviewed. In particular, tube hydroforming processes and spinning processes are examined. Advanced numerical tools are utilized with the aim to design proper forming operations able to produce sound components. Furthermore, as far as the spinning process is concerned, experimental verifications are carried out to confirm the effectiveness of the numerical predictions.
Evaluating creep in metals by grain boundary extraction using directional wavelets and mathematical morphology
2001
Abstract It is economically important for manufacturers of high-temperature machines to be able to measure creep so that they can predict residual service life more accurately. This paper describes and refines an image analysis method for evaluating creep in laboratory test pieces. It is a preliminary study of how to extract relevant information for creep measurement by cavities counting. Sample preparation for quantification by image analysis is an important step determining the further development of the image analysis technique. Grain boundary extraction, which is directional information, is the major question to be overcome before measurement can be automated. The search for a crest-lin…
A force measuring based strategy for failure prevention in incremental forming
2006
Abstract Incremental forming processes show a number of advantages compared to the traditional processes but, at the same time, some drawbacks are clearly known. Current problems, include the slowness of the process, low accuracy and a lack of knowledge in the field of material formability. This paper is focused on the latter issue: an industrially oriented methodology for detecting the approach of failure in incremental forming is proposed. The approach is based on the analysis of the trend of the forming force in order to assess whether the process can be run safely. If not, a proper strategy, to avoid material failure, is proposed and experimentally validated.