1,721,110 research outputs found
Characterization of stress-strain behavior of superplastic titanium alloy by free bulging tests with pressure jumps
No full textThe work is dedicated to determination of stress-strain behavior of Ti6Al4V alloy deformed in conditions of biaxial tension provided by free bulging testing. The dome height during each test was continuously measured and recorded using a magnetostrictive position transducer. All the tests were performed using stepped pressure regime with jump pressure changing between two values at evenly spaced time moments. This experimental technique provides the possibility to study strain rate sensitivity index variation during the test and subsequently construct strain and strain rate dependent material model. The output data of each test include the evolution of dome height, subsequent pressure regime and final thickness of the specimen at the dome pole. In the framework of this study the processing of such data in order to evaluate the material behavior is discussed. Inverse analysis with different material models was implemented as well as special direct technique allowing one to construct stress-strain curves based on the results of free bulging tests with pressure jumps. The obtained material model was verified by finite element simulation
Characterizing a superplastic AA5083 alloy by the blow forming technique and numerical finite element analysis
No full textWire laser additively reinforced blanks: Effect of the laser power on the bending strength of a single layer reinforcement
No full textThis study investigates the application of Wire Laser Metal Deposition (w-LMD), a form of Directed Energy Deposition (DED) additive manufacturing, to enhance the production process of automotive components, specifically through the development of patchwork blanks with localized reinforcements. The research focuses on reinforcing 22MnB5 steel sheets with beads of 316L steel using a laser beam at various power levels, aiming to achieve maximum strength with minimal use of material. The resulting components, referred to as wire-Laser Additively Reinforced Blanks (w-LARB), demonstrated a substantial increase in strength, up to 87%, as verified by bending tests. Notably, the study reveals that a relatively low laser power can still yield significant mechanical improvements, underlining the efficiency of the process in terms of material usage and energy consumption. Furthermore, the high repeatability of the w-LMD process confirms its potential for widespread industrial adoption in automotive manufacturing
High temperature characterization of a 2024 aluminium alloy by tensile tests and the blow forming technique
No full textA numerical-experimental approach to material characterization and process analysis in the blow forming process
No full textIn carrying out a superplastic forming process, the first step for the process optimization is a detailed material
characterization. The achievement of a successfully formed component is strictly related to the material behaviour:
commonly, several tensile tests are carried out at different temperatures and strain rates for locating the best deformation
parameters, corresponding to which maximum uniform elongation of the material can be found. Additionally, characterization
is needed also for estimating material parameters to numerically model the process. Numerical modelling is a necessary step
when the pressure profile of a blow forming process has to be optimized. In this paper authors present a methodology for
estimating material parameters on the basis of few bulge tests and for analysing the superplastic forming process.
Temperature and pressure influences are analysed by means of free inflation tests. Material parameters are calculated starting
from an analytical approach and refining the solution by an inverse analysis. A 3D numerical model of the process has been
then created and used for evaluating the pressure profile that is able to keep the strain rate value in the sheet close to a target
value. A numerical-experimental comparison has been done for testing the model capability and effectiveness of the pressure
profile in a prismatic closed die blow forming test. Good agreement has been found between experimental results and
numerical simulations. Thickness distribution measurements, optical microscope observations, post-forming characteristics
evaluation have been performed to compare constant pressure and constant strain rate tests
The role of the numerical simulation in superplastic forming process analysis and optimization
No full textNumerical simulation took root in the last few decades in the superplastic forming field as one of the most dominant tools for process analysis and optimization. The big role of the simulation can be found in many areas concerning the study and the implementation of the forming process. The purpose of this paper is to outline some of the main applications of the numerical simulation in superplastic forming that can be found in the material characterization phase, in the simulation of forming tests and in the optimization of the process. A brief overview of results that can be found in literature is given with special regard to Finite Element numerical simulation of metal sheet Superplastic Forming
Characterization of a superplastic aluminium alloy ALNOVI-U through free inflation tests and inverse analysis
No full textNumerical methods are widespread in forming applications since a deeper understanding and a finer calibration of the process can be reached without most of the assumptions used in analytical approaches. In this calibration procedure the characterization of the material behaviour is an important preliminary step that cannot be avoided. Experimental tests can be numerically modelled and material constants can be found by inverse methods making numerical results as close as possible to experimental ones. In this work material parameters of a superplastic aluminium alloy have been found by experimental forming tests and an inverse analysis. Constant pressure free inflation tests were firstly performed to find the optimal range for temperature and strain rate values. Material constants were then calculated, on the basis of these tests, minimizing errors between experimental and numerical data through a gradient based optimization iterative procedure. Constant strain rate experimental tests were finally used to refine material parameters and to gain a better agreement between experiments and numerical simulations
Tangential bending and stretching of thin magnesium alloy sheets in warm conditions
No full textThe present work aims at studying the tangential bending process (wiping) and the combined effect of a bending and stretching stress on thin (0.7 mm) magnesium alloy (AZ31) sheets when working in warm conditions. The test equipment was designed in order to heat the sheet only in the bending region and to stretch the sheet after the wiping process; it was used for investigating the parameters affecting the stretch-bending state of stress in the sheet, quite common in the stamping process. A preliminary screening analysis over a large set of process parameter was performed using a full factorial design. As a result, only the effect of the temperature, the speed and the bend radius were further investigated according to a central composite design and using the springback factor and the maximum stretching load as response variables. The present work can give useful guidelines in the warm forming of AZ31 Mg alloy sheets in terms of key process parameters, fillet radii of the equipment, material stretch-bending strength (according to temperature, bending radius and speed) and precision of the final part (springback amount)
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