Wyniki wyszukiwania - BazTech

1

Difference between 2D and 3D capturing and influence of strain rate on FLC diagram of DC.01 steel

Potužník L., Konopík P., Rund M.

Journal of Achievements in Materials and Manufacturing Engineering

|

2014

|

Vol. 65, nr 1

32--37

EN

Purpose: The aim of this work is to develop a method for evaluating forming limit curves measured at high strain rates using drop tower while specimens are being captured by high-speed camera (2D). Design/methodology/approach: This article describes the first step to establishing such method – verification of compatibility between 3D and 2D capturing by ARAMIS system. Findings: Within this work, FLD recorded in 3D and 2D mode were determined. After correction of the angle α between projection onto the normal plane to direction of loading and tangent in the point where crack occurred, the obtained FLD diagram were almost identical. Research limitations/implications: Optical methods, such as digital image correlation used by ARAMIS measuring system, offer very detailed information of material’s surface at high resolution while significantly reducing the preparation and evaluation time for specimens testing. Originality/value: The analysis of true plane major strains in the forming limit diagram (FLD) is still the most established method for failure detection of sheet metal forming processes in industrial praxis. With the prerequisite of linear strain paths it is very simple to predict the start of necking by using the FLD.

2

Numerical determination of the forming limit diagrams

Pepelnjak T., Kuzman K.

Journal of Achievements in Materials and Manufacturing Engineering

|

2007

|

Vol. 20, nr 1-2

375-378

EN

Purpose: At present the industrial practice demands a reliable determination of forming limits which assures the prediction of properly selecting the forming process in a digital environment. Therefore, technological limits defined with the forming limit diagrams (FLDs) have to be known. The experimental evaluation of FLDs for sheet metal is time consuming and demands expensive equipment. The experimental work could be omitted by predicting the FLD with numerical simulations. Design/methodology/approach: The paper presents a methodology to determine the entire range of the FLD for sheet metal in a digital environment. The Marciniak testing procedure simulated with the FEM program ABAQUS was selected to determine the FLD. To assure the reliability of the developed method, different materials were analysed: two types of deep drawing steel, an aluminium 3000 alloy, and a Ti-alloy. The selected materials have different mechanical properties and sheet thicknesses ranging from 0.5 mm to 1.23 mm. For the verification of numerically obtained results parallel experimental determinations of the FLDs were performed showing a good correlation between the FLDs obtained by both approaches. Findings: A specially developed method for the evaluation of the thickness strain as a function of time as well as the first and the second time derivation of the thickness strain enable the determination of the onset of necking. Research limitations/implications: The presented method of the digital evaluation of the FLDs is still in a developmental phase and needs further improvements for industrial practice. However, in some cases the numerical approach had already been used for a fast prediction of the FLD prior to performing the experiments. At the current level the developed program still needs an expert to support it in some critical decisions. Originality/value: Considering some methological improvements and automation procedures the developed method could be used in everyday practice.

3

Produkcja blach magnezowych - stan obecny i perspektywy

Kawalla R., Ullman M.

Obróbka Plastyczna Metali

|

2006

|

T. 17, nr 4

21-26

PL

Magnez i jego stopy cieszą się coraz większym zainteresowaniem przemysłu metalowego. Materiały te łączą gęstość z właściwościami mechanicznymi i fizycznymi w sposób, który czyni je doskonale przydatnymi do zastosowań w lekkich konstrukcjach. Mają zatem wysoki potencjał innowacyjny. Zalety magnezu są już intensywnie wykorzystywane w wyrobach odlewanych. Dotychczas przerobione plastycznie stopy magnezu stosowane były na małą skalę. Głównymi powodami tego stanu rzeczy była mała osiągalność półproduktów ze stopów przerobionych plastycznie i wysoka cena. W niniejszej pracy omówiona została produkcja wyrobów z blach i taśm, z przedstawieniem stanu aktualnego i motywów intensywnego rozwoju. W części końcowej, na przykładzie stopów magnezu AZ31, rozważono właściwości materiału. Szczególnie ciekawy jest tu wpływ temperatury na zmianę właściwości. Celem lepszej oceny zachowania się materiału podczas kształtowania oraz granicy plastyczności w różnych stanach naprężenia i kształtowania, stosuje się wykresy odkształceń granicznych.

EN

Magnesium and its alloys are becoming more and more interesting for the metal working industry. These mate-rials combine density with mechanical and physical properties in a way that gives them excellent suitability for light-weight applications. Therefore, they offer a high innovation potential. The advantages of magnesium are already being used intensively in cast products. So far, wrought magnesium alloys have been used only on a small scale. The major reasons for this are the low availability of semi-finished products made of wrought alloys and the high price. This paper will discuss the production of sheet and strip products, looking into the current state of development and the motives for the intensive development. At the end, material properties will be considered using the magnesium alloys AZ31 as an example. Thereby the influence of temperature on the change of properties is of special interest. In addition, for better assessment of the forming behaviour as well as of the limit of forming at different stress- and forming states, forming limit diagrams are used.