Mechanical Behaviour and Springback Study of an Aluminium Alloy in Warm Forming Conditions

This study deals with the mechanical behaviour and material modelling of an AA5754-O alloy at elevated temperature. Experimental shear tests were performed from room temperature up to 200°C, and the material behaviour has been identified with both shear and tensile tests, as a function of temperature. To analyse the influence of temperature during forming over springback, a split-ring test is used. Experimental results are obtained and compared to numerical simulations performed with the finite element in-house code DD3IMP. The numerical process of ring splitting is performed with the in-house code DD3TRIM. The main observed data are force-displacement curves of the punch during forming, cup thickness at the end of forming, and ring gap after splitting. It is shown that all these parameters are strongly dependent on the forming temperature. A correlation is obtained between experimental data and numerical simulation for the evolution of punch force and opening after springback as a function of temperature. The distribution of the tangential stress in the cup wall is the main factor influencing the springback mechanism in warm forming condition.

Download Full-text

Material Characterization and Mid-Span Bending Capacity With Finite Element Simulated Predictions

ASME 2011 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Volume 2 ◽

10.1115/smasis2011-5097 ◽

2011 ◽

Author(s):

Walter Anderson ◽

Ahmadreza Eshghinejad ◽

Mohammad Elahinia

Keyword(s):

Finite Element ◽

Load Capacity ◽

Tensile Tests ◽

Unified Model ◽

Radius Of Curvature ◽

Maximum Displacement ◽

Test Fixture ◽

Different Temperatures ◽

Bending Capacity ◽

Force Displacement

Intelligent materials have been the subject of research for many years. Shape memory alloys (SMAs) are a type of intelligent material that has been targeted for many different uses; such as actuators, sensors and structural supports. SMAs are attractive as actuators due to their large energy density. Although a great deal of information is available on the axial load capacity and on the tip force for SMA tweezer-like devices, there is not enough information about the load capacity at mid-span, especially at the macro-level. Imposed displacement at mid-span experimental evaluation of an SMA beam in the austenitic and martensitic regimes has been studied. To this end, a specimen of near equi-atomic nitinol was heat-treated (shape set) into a ‘U’ shape and loaded into a custom test fixture such that the boundary conditions of the beam are approximated as roller-roller; and the sample was deformed at different temperatures while reaction forces were measured. The displacement is near maximum displacement of the U shape without causing a change in concavity, thus full-scale capacity is shown. Additionally, Unified Model (finite element) predictions of the experimental response are also presented, with good agreement. Due to the robust nature of the Unified Model, geometric parameter variations (wire diameter and radius of curvature) were then simulated to encompass the design envelop for such an actuator. The material properties needed as inputs to the Unified Model were obtained from constant temperature tensile tests of a specimen subjected to the same heat treatment (shape set straight). The resultant critical stresses were then extracted using the tangent method similar to the one described in ASTM F-2082. It is worth noting that the specimen was trained before the stress value extraction, but the transversely loaded specimen was not trained due to the difficulty involved (inherent uneven stress distribution). The contribution of this work is the presentation of experimental results for transverse (mid-span) loading of a nitinol wire and the simulation results allowing for design of a proper actuator with known constraints on force, displacement or temperature (2 of 3 needed). In other words, this work could be used as a type of 3D look-up table; e.g. for a desired force/displacement, the required temperatures are given. Future work includes developing a sensor-less control strategy for simultaneous force/displacement control.

Download Full-text

The tensile behaviour of biaxial and triaxial braided fabrics

Journal of Industrial Textiles ◽

10.1177/1528083716654469 ◽

2016 ◽

Vol 47 (8) ◽

pp. 2184-2204 ◽

Cited By ~ 9

Author(s):

Duchamp Boris ◽

Legrand Xavier ◽

Soulat Damien

Keyword(s):

Mechanical Properties ◽

Experimental Study ◽

Mechanical Behaviour ◽

Tensile Tests ◽

Uniaxial Tensile ◽

Tensile Behaviour ◽

Linear Mass ◽

Double Peak ◽

Specific Behaviour ◽

Braiding Angle

The tensile behaviour of braid reinforcement is classically described by the behaviour of composite elaborated from these reinforcements. Few studies concern the tensile behaviour of braided fabrics. In this paper biaxial and triaxial braids are manufactured on a braiding loom. The evolution of key parameters as linear mass and braiding angle in function of process parameters is presented. Braid reinforcements are characterized in uniaxial tensile. The mechanical behaviour is analysed and compared in function of the braiding angle, but also different kinds of braid are considered. A specific behaviour called “double-peak” is identified for triaxial braids which have a higher braiding angle. The evolution of the braiding angle measured during tensile tests gives a comprehension on the mechanical behaviour of dry braids. Associated with this experimental study, an analytical model is also proposed, to predict mechanical properties of braid reinforcements.

Download Full-text

Tensile Tests of Plantation Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3546525 ◽

1940 ◽

Vol 13 (3) ◽

pp. 451-467

Author(s):

I. Slbiriakoff

Keyword(s):

American Chemical Society ◽

Tensile Tests ◽

Chemical Society ◽

Testing Procedure ◽

Ring Test ◽

Open Steam ◽

Fixed Weight ◽

Roll Temperature ◽

Commercial Testing ◽

The Tropics

Abstract The investigation which has just been described can be summarized as follows: (1) A technique for the commercial testing of plantation rubber has been developed which is simple and precise, and by means of which it is possible to reproduce control tests, a feature which is indispensable if rubber is to be sold on a basis of quality rather than superficial appearance. (2) The tentative specifications for testing rubber drawn up by the Crude Rubber Committee of the Division of Rubber Chemistry of the American Chemical Society have been found acceptable as a basis for this testing procedure. (3) It has been found necessary, however, to revise the specifications of the Crude Rubber Committee in some ways and to amplify them, so that they fulfill the three conditions described above and also conform to the particular working conditions of laboratories in the tropics. The revisions to the Crude Rubber Committee specifications include: (1) The use of an autoclave for vulcanizing in open steam. (2) A mill roll temperature of 65° C instead of 70° C. (3) A definite, fixed weight of batch, containing 200 grams of rubber, plus accessory ingredients. (4) A temperature of 25° to 30° C during testing. (5) The use of ring test-specimens instead of dumb-bell specimens.

Download Full-text

Bearing Capacity Analysis on Slotted End Plate Connection Joints of Different Types

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.166-169.764 ◽

2012 ◽

Vol 166-169 ◽

pp. 764-769

Author(s):

Ruo Hui Qiang ◽

Ming Zhou Su ◽

Junfen Yang ◽

Jinbo Cui

Keyword(s):

Bearing Capacity ◽

Failure Modes ◽

Great Influence ◽

Mechanical Behaviors ◽

End Plate ◽

Different Types ◽

Plastic Stage ◽

Plate Connection ◽

Force Displacement ◽

Main Factor

Four different types of full-scale slotted end plate (SEP) connection joints are tested to determine their failure modes and damage mechanisms under ultimate loading. Researches on mechanical behaviors of I-type, T-type, U-type and Groove SEP connection joints bearing compression are studied, which also analyze their force-displacement behaviors and developing processes of deformation and strain. The results show that the bearing capacities of I, grooved, T and U types SEP connections are increased gradually, which indicate the SEP’s type has great influence on the ultimate strength of joints. The instability of SEP is the main factor to cause the loss of bearing capacity of the connection, which is shown through the development of strain, that SEP enters into plastic stage and the other regions still are elastic.

Download Full-text

Carbon Powder as Additive in Near-Net-Shaping of Mechanical Components through Warm Forming Route

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.594-595.948 ◽

2013 ◽

Vol 594-595 ◽

pp. 948-952

Author(s):

Mujibur M. Rahman ◽

N.A.A.A. Kadir

Keyword(s):

Carbon Content ◽

Density Measurement ◽

Warm Forming ◽

Design Parameters ◽

Carbon Powder ◽

Forming Temperature ◽

Die Compaction ◽

Mechanical Components ◽

Near Net Shaping ◽

Net Shaping

This paper presents the study of carbon powder as additive in near-net-shaping of mechanical components through warm forming route. Three design parameters, i.e., carbon content (wt %), forming temperature, and sintering schedule were investigated. Iron powder ASC 100.29 was mechanically mixed with different wt% of carbon and copper powder for 30 minutes to prepare the feedstock. Green compacts were then formed through uni-axial die compaction process at 30°C and 180oC. The defect-free green compacts were then sintered at 1000oC in an argon gas fired furnace at a heating/cooling rate of 5oC/minute for 30, 60, and 90 minutes, respectively. The green samples as well the sintered products were characterized through relative density measurement, radial shrinkage, and microstructure evaluation. The results revealed that excessive carbon content contributed adverse effect to the final quality of the products.

Download Full-text

Tensile Tests with Flat (Straight) Test-Specimens

Rubber Chemistry and Technology ◽

10.5254/1.3546344 ◽

1938 ◽

Vol 11 (1) ◽

pp. 214-223

Author(s):

R. Ariano

Keyword(s):

Test Specimen ◽

Testing Machine ◽

American Chemical Society ◽

Tensile Tests ◽

Chemical Society ◽

Ring Test ◽

Rubber Ring ◽

Long Time ◽

Fundamental Objection ◽

Center Section

Abstract It is of course a well known fact that both ring test-specimens and flat or straight test-specimens are used in testing rubber. Ring test-specimens have for a long time been the most generally used type for testing rubber mixtures, whereas in American laboratories straight test-specimens are preferred. Ring test-specimens are the more convenient to use, but they are open to one fundamental objection, that different parts of the cross section of the rubber are elongated to different extents at any particular moment. Even straight test-specimens are not free from objectionable features. With this type of test-specimen, the inequality in the deformation at any particular instant results from the necessity of having enlarged ends for the testing machine to avoid breakage of the test-specimens in the jaws. It therefore becomes necessary to study systematically the form and dimensions of the end sections of the test-specimens and of the junction of these end sections with the central section, so that the points of rupture will not become localized in the sections in the jaws or close to these sections. As a matter of fact, an extensive investigation of this problem has been made by the Physical Testing Committee of the Rubber Division of the American Chemical Society. By a proper study of the shape of the test-specimen, it is possible to design the test-specimen so that rupture occurs in the center section and therefore so that satisfactory tensile strength measurements are obtained.

Download Full-text

Flow Stress Experimental Determination for Warm-Forming Process

ASME 2011 International Manufacturing Science and Engineering Conference, Volume 2 ◽

10.1115/msec2011-50209 ◽

2011 ◽

Author(s):

Ting Fai Kong ◽

Luen Chow Chan ◽

Tai Chiu Lee

Keyword(s):

Stainless Steel ◽

Flow Stress ◽

Room Temperature ◽

Warm Forming ◽

Recrystallization Temperature ◽

Process Conditions ◽

Compression Tests ◽

Forming Process ◽

Forming Temperature ◽

Flow Stress Data

Warm forming is a manufacturing process in which a workpiece is formed into a desired shape at a temperature range between room temperature and material recrystallization temperature. Flow stress is expressed as a function of the strain, strain rate, and temperature. Based on such information, engineers can predict deformation behavior of material in the process. The majority of existing studies on flow stress mainly focus on the deformation and microstructure of alloys at temperature higher than their recrystallization temperatures or at room temperature. Not much works have been presented on flow stress at warm-forming temperatures. This study aimed to determine the flow stress of stainless steel AISI 316L and titanium TA2 using specially modified equipment. Comparing with the conventional method, the equipment developed for uniaxial compression tests has be verified to be an economical and feasible solution to accurately obtain flow stress data at warm-forming temperatures. With average strain rates of 0.01, 0.1, and 1 /s, the stainless steel was tested at degree 600, 650, 700, 750, and 800 °C and the titanium was tested at 500, 550, 600, 650, and 700 °C. Both materials softened at increasing temperatures. The overall flow stress of stainless steel was approximately 40 % more sensitive to the temperature compared to that of titanium. In order to increase the efficiency of forming process, it was suggested that the stainless steel should be formed at a higher warm-forming temperature, i.e. 800 °C. These findings are a practical reference that enables the industry to evaluate various process conditions in warm-forming without going through expensive and time consuming tests.

Download Full-text

Anisotropic mechanical behaviour of calendered nonwoven fabrics: Strain-rate dependency

Journal of Composite Materials ◽

10.1177/0021998320976795 ◽

2020 ◽

pp. 002199832097679

Author(s):

V Cucumazzo ◽

E Demirci ◽

B Pourdeyhimi ◽

VV Silberschmidt

Keyword(s):

Strain Rate ◽

Mechanical Behaviour ◽

Mechanical Response ◽

Tensile Tests ◽

Elastic Response ◽

Uniaxial Tensile ◽

Rate Dependency ◽

Fibrous Matrix ◽

Nonwoven Fabrics ◽

Linear Elastic

Calendered nonwovens, formed by polymeric fibres, are three-phase heterogeneous materials, comprising a fibrous matrix, bond-areas and interface regions. As a result, two main factors of anisotropy can be identified. The first one is ascribable to a random fibrous microstructure, with the second one related to orientation of a bond pattern. This paper focuses on the first type of anisotropy in thin and thick nonwovens under uniaxial tensile loading. Individual and combined effects of anisotropy and strain rate were studied by conducting uniaxial tensile tests in various loading directions (0°, 30°, 45°, 60° and 90° with regard to the main fabric’s direction) and strain rate (0.01, 0.1 and 0.5 s−1). Fabrics exhibited an initial linear elastic response, followed by nonlinear strain hardening up to necking and final softening. The studied allowed assessment of the extent the effects of loading direction (anisotropy), planar density and strain rate on the mechanical response of the calendered fabrics. The evidence supported the conclusion that anisotropy is the most crucial factor, also delineating the balance between the fabric’s load-bearing capacity and extension level along various directions. The strain rate produced a marked effect on the fibre’s response, with increased stress at higher strain rate while this effect in the fabric was small. The results demonstrated the differences of the mechanical behaviour of fabrics from that of their constituent fibres.

Download Full-text

Identification and Modelling of the Behaviour of a Duplex Stainless Steel by Methods of Scale Changing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.482.231 ◽

2005 ◽

Vol 482 ◽

pp. 231-234 ◽

Cited By ~ 3

Author(s):

Suzanne Degallaix ◽

Florence Jaupitre ◽

Djimedo Kondo ◽

Philippe Quaegebeur ◽

Pierre Forget

Keyword(s):

Stainless Steel ◽

Duplex Stainless Steel ◽

Mechanical Behaviour ◽

Linear Models ◽

Constant Strain Rate ◽

Young Modulus ◽

Tensile Tests ◽

Selective Dissolution ◽

Austenitic Phase ◽

Non Linear

In order to model the mechanical behaviour of an austenitic-ferritic duplex stainless steel thanks to "composite" micromechanical non-linear models, its microstructure was analysed and the mechanical behaviour of each phase was characterised. The microstructural morphology of this steel was studied by selective dissolution of the austenitic phase. The microstructure consists of unconnected austenite islands dispersed in a ferritic matrix. Nano-indentation tests were carried out on each phase. These tests allowed to obtain the hardness and the Young modulus of each phase. A non-linear homogenization approach (secant and incremental formulations) was implemented and the results were compared to the monotonous macroscopic tensile tests carried out at constant strain rate. It allowed us to evaluate the relevance of the non-linear homogeneization models for the description of the elasto-plastic behaviour of the studied duplex stainless steel.

Download Full-text