A computer-aided method for calculating the distributions of strain-rate and strain from an experimental flow field

1976 ◽  
Vol 11 (1) ◽  
pp. 26-31 ◽  
Author(s):  
L E Farmer ◽  
P L B Oxley
Keyword(s):  
Flow Field ◽  
Computer Program ◽  
Strain Rate ◽  
Plane Strain ◽  
Strain Rates ◽  
Simple Geometry ◽  
Punch Velocity ◽  
Computer Aided ◽  
Intersection Points

A method of calculating strain-rates and strains from an experimental flow field is developed using simple geometry with polynomials used to represent small segments of the experimental streamlines and the corresponding distance/time along streamline curves. The method is applied to an experimental flow field for plane strain extrusion obtained using printed grids (0.002 inch square), the input to the computer program being the co-ordinates of the grid intersection points and the punch velocity.

An Investigation of the Dynamic Recrystallisation Behaviour of Magnesium AZ31 Alloy at 450°C Using Plane Strain Compression Testing as a Tool

2012 ◽  
Vol 715-716 ◽  
pp. 164-169
Author(s):  
Bradley P. Wynne ◽  
R. Bhattacharya ◽  
Bruce Davis ◽  
W.M. Rainforth
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Testing Machine ◽  
Az31 Alloy ◽  
Plane Strain Compression ◽  
Strain Rates ◽  
Basal Texture ◽  
Magnesium Az31 ◽  
Dynamic Recrystallisation ◽  
Double Hit

The dynamic recrystallisation (DRX) behaviour of magnesium AZ31 is investigated using a plane strain compression (PSC) testing machine at 450°C. The variables included strain rate, double hit including intermittent anneal and double hits with different strain rate at each hit. The alloy shows higher peak stress and strain with increasing strain rates. Predominant basal texture with different intensities are observed at different strain rates. The annealing treatment between double tests leads to strong basal texture. Reversal of strain rate during double hit results in similar flow curves. This shows that in AZ31 alloy, DRX mechanism is independent of the initial microstructure and only depends on the test condition viz. temperature, strain rate and total equivalent strain.

Experimental Estimation of Strain Rate during FSW of Al-Alloy Using Plane-Strain Compression

2008 ◽  
Vol 580-582 ◽  
pp. 299-302 ◽  
Author(s):  
Kunitaka Masaki ◽  
Yutaka S. Sato ◽  
Masakatsu Maeda ◽  
Hiroyuki Kokawa
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Travel Speed ◽  
Plane Strain Compression ◽  
Stir Zone ◽  
Grain Structure ◽  
Al Alloy ◽  
Strain Rates ◽  
Friction Stir ◽  
Grain Structures

Friction stir welding (FSW) makes the stir zone with fine recrystallized grain structure. The recrystallized grains would be formed through dynamic recrystallization at high temperatures and high strain-rate. The present study experimentally simulated the dynamically recrystallized microstructure of a friction stir welded Al alloy 1050 produced at 600 rpm rotation and 100 mm/min travel speed, using combination of the plane-strain compression at various strain rates and the subsequent cooling along the cooling cycle of FSW. The equiaxed grain structures similar to the microstructure of the stir zone were produced at strain rates between 0.1 and 32 s-1; the grain size decreased with increasing strain rate. Strain rate during the FSW could be estimated to be about 1.8 s-1. The present study suggests that plane-strain compression test can simulate the recrystallized grain structure of the friction stir welds.

scholarly journals Factors Influencing the Plane-Strain Crack Toughness Values of a Structural Steel

1969 ◽  
Vol 91 (3) ◽  
pp. 506-511 ◽  
Author(s):  
A. K. Shoemaker
Keyword(s):  
Strain Rate ◽  
Structural Steel ◽  
Yield Stress ◽  
Plane Strain ◽  
Stress Level ◽  
Room Temperature ◽  
Fatigue Cracking ◽  
Strain Rates ◽  
Fatigue Stress ◽  
Plane Strain Crack

An investigation was conducted to determine the effects of the variables; temperature, strain rate, and precracking fatigue-stress level, on plane-strain crack toughness values of a rate and temperature-sensitive steel. The crack toughness behavior of a 3/4-in-thick structural steel plate, which had a static room-temperature yield stress of 45,000 psi, was examined over the temperature range from −280 to 0 deg F for strain rates of 8 × 10−5/sec, 3 × 103/sec, and 1.5/sec. Crack toughness data, which were obtained from notched bend and single-edge-notched specimens, are presented for precracking conditions obtained at a maximum nominal fatigue stress of 25 percent and 50 percent of the room-temperature yield stress. The plane-strain crack toughness, KIc-values showed only a small sensitivity to changes in temperature and no effect due to changes in strain rate. The beginning of the transition from plane-strain to plane-stress conditions occurred at successive increases in temperature for increasing strain rate. The requirement of B > 2.5 × (KIc/σys)2 for plane-strain behavior of high-strength steels was also valid for this material when the yield stress was evaluated at the test temperature and strain rate. Increasing the fatigue-cracking stress level from 25 to 50 percent of the room-temperature nominal yield stress increased the apparent KIc-values. The data showed that a necessary condition for obtaining valid KIc-values is that the plastic-zone size which develops during fatigue cracking at room temperature must be less than that which occurs at the low temperatures and elevated strain rates of the KIc tests.

An Investigation of Microstructure Inhomogeneity in Waspaloy Subjected to Plane Strain Compression Testing

2007 ◽  
Vol 558-559 ◽  
pp. 589-594 ◽  
Author(s):  
M.J. Thomas ◽  
Bradley P. Wynne ◽  
Eric J. Palmiere ◽  
Ken P. Mingard ◽  
Bryan Roebuck
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Plane Strain ◽  
High Strain ◽  
Plane Strain Compression ◽  
Strain Rates ◽  
Nickel Based Superalloy ◽  
Nominal Strain ◽  
Plane Strain Compression Test ◽  
Low Strain Rate

An assessment of the inhomogeneity of microstructure generated within plane strain compression test specimens has been performed using the nickel based superalloy, Waspaloy. Two variables were investigated: the effect of strain rate and the effect of friction at the tool/specimen interface. Tests were performed at 1040°C at nominal strain rates of 0.01 and 1 s-1 with and without a glass based lubricant. At the low strain rate the microstructure was relatively homogeneous regardless of the friction conditions. At the high strain rate there was significant microstructure variation from surface to mid plane which was further exaggerated by increased friction. Quantification of the inhomogeneity, however, is non-trivial in this alloy due to the complicated recrystallisation behaviour it exhibits and difficulty in differentiating between recrystallised and non-recrystallised grains.

Investigation of the Hot Deformation Behavior of an Al-Mg-Sc-Zr Alloy under Plane Strain Condition

2014 ◽  
Vol 611-612 ◽  
pp. 76-83 ◽  
Author(s):  
Johannes Taendl ◽  
Martina Dikovits ◽  
Cecilia Poletti
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Hot Deformation Behavior ◽  
Flow Curves ◽  
Increasing Temperature ◽  
Zr Alloy

This study investigates the hot deformation behavior of a new Al-Mg-Sc-Zr alloy under plane strain conditions. Flow curves corrected for deformation heating were calculated for strain rates between 0.01 and 10s-1 in a temperature range of 200 to 400°C. To evaluate the deformation behavior, strain rate sensitivity as well as flow localization parameter maps were calculated for strains of 0.2, 0.4, and 0.6. In addition, microstructural investigations and hardness measurements were performed for selected samples. It was shown that the flow stress decreased with deacreasing strain rate and increasing temperature. The best formability was observed for high strain rates and low temperatures as well as for low strain rates and high temperatures. In these cases no flow instabilities were observed.

scholarly journals Plane strain tension fracture at high strain rate

2021 ◽  
Vol 250 ◽  
pp. 01020
Author(s):  
Morwan Adlafi ◽  
Bertrand Galpin ◽  
Laurent Mahéo ◽  
Christian C. Roth ◽  
Dirk Mohr ◽  
...  
Keyword(s):  
Stress State ◽  
High Strain Rate ◽  
Strain Rate ◽  
Plane Strain ◽  
High Strain ◽  
Tension Stress ◽  
Outer Diameter ◽  
Strain Rates ◽  
High Strain Rates ◽  
Plane Strain Tension

Under plane stress conditions, most micromechanical and phenomenological models predict a minimum in ductility for plane strain tension stress state. Therefore, the stress state of plane strain tension plays a crucial role in many forming and crash applications and the reliable measurement of the strain to fracture for plane strain tension is particularly crucial when calibrating modern fracture initiation models. Recently, a new experimental technique has been proposed for measuring the strain to fracture for sheet metal after proportional loading under plane strain conditions. The basic configuration of the new setup includes a dihedral punch which applies out-of-plane loading onto a Nakazima-type of discshaped specimen with two symmetric holes and an outer diameter of 60 mm. In the present work, the applicability of the test is extended to high strain rates. High strain rates of about 100/s to 200/s are obtained using a drop weight tower device with an original sensor for load measurements. Quasi static tests are also performed for comparison, keeping the same specimen geometry, image recording parameters and set-up. The effective strains at fracture are compared from quasi-static to high strain rate loading for three different materials, i.e one aluminium alloy and two steels.

scholarly journals Experimental study of the stress state and strain rate dependent mechanical behaviour of TRIP-assisted steels

2021 ◽  
Vol 250 ◽  
pp. 05003
Author(s):  
A. Pontillo ◽  
C. Lonardi ◽  
S. Chandran ◽  
F. Vercruysse ◽  
L. Corallo ◽  
...  
Keyword(s):  
Strain Rate ◽  
Plane Strain ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strain Rates ◽  
Plane Shear ◽  
Rate Dependent ◽  
Stress States

This paper presents an investigation into the effect of different stress states and strain rates on the austenite-to-martensite transformation during plastic straining of a Q&P steel. Different stress states are imposed to the steel using purposed-designed samples. The sample geometries, including in-plane shear, dogbone and plane strain samples, are optimised by finite element modelling. Tensile tests are performed at different strain rates of 0.001 s-1, 10 s-1 and 500 s-1. Digital image correlation is used to capture the strain fields during the entire deformation process. The mechanical results indicate a positive strain rate sensitivity for both the shear and plane strain specimens and a negative strain rate sensitivity for the dogbone sample. In addition, the influence of the strain rate on the strain level is more pronounced for the shear than for the plane strain specimens and for the dogbone samples.

The effects of strain and strain rate on residual microstructures in copper

1986 ◽  
Vol 44 ◽  
pp. 420-421
Author(s):  
M. F. Stevens ◽  
P. S. Follansbee
Keyword(s):  
Strain Rate ◽  
Applied Stress ◽  
Threshold Stress ◽  
Rate Sensitivity ◽  
Viscous Drag ◽  
Strain Rates ◽  
Strain And Strain Rate ◽  
Threshold Strength ◽  
Mechanism Transition ◽  
Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

scholarly journals A Review on Mechanical Properties of Natural Fibre Reinforced Polymer Composites under Various Strain Rates

2021 ◽  
Vol 5 (5) ◽  
pp. 130
Author(s):  
Tan Ke Khieng ◽  
Sujan Debnath ◽  
Ernest Ting Chaw Liang ◽  
Mahmood Anwar ◽  
Alokesh Pramanik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Polymer Composites ◽  
Stress Transfer ◽  
Natural Fibre ◽  
Transfer Efficiency ◽  
Strain Rates ◽  
Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Fibre Matrix

With the lightning speed of technological evolution, the demand for high performance yet sustainable natural fibres reinforced polymer composites (NFPCs) are rising. Especially a mechanically competent NFPCs under various loading conditions are growing day by day. However, the polymers mechanical properties are strain-rate dependent due to their viscoelastic nature. Especially for natural fibre reinforced polymer composites (NFPCs) which the involvement of filler has caused rather complex failure mechanisms under different strain rates. Moreover, some uneven micro-sized natural fibres such as bagasse, coir and wood were found often resulting in micro-cracks and voids formation in composites. This paper provides an overview of recent research on the mechanical properties of NFPCs under various loading conditions-different form (tensile, compression, bending) and different strain rates. The literature on characterisation techniques toward different strain rates, composite failure behaviours and current challenges are summarised which have led to the notion of future study trend. The strength of NFPCs is generally found grow proportionally with the strain rate up to a certain degree depending on the fibre-matrix stress-transfer efficiency. The failure modes such as embrittlement and fibre-matrix debonding were often encountered at higher strain rates. The natural filler properties, amount, sizes and polymer matrix types are found to be few key factors affecting the performances of composites under various strain rates whereby optimally adjust these factors could maximise the fibre-matrix stress-transfer efficiency and led to performance increases under various loading strain rates.

scholarly journals Experimental Study on Biaxial Dynamic Compressive Properties of ECC

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1257
Author(s):  
Shuling Gao ◽  
Guanhua Hu
Keyword(s):  
Strain Rate ◽  
Lateral Pressure ◽  
Deformation Modulus ◽  
Strain Curve ◽  
Peak Stress ◽  
Pressure Level ◽  
Strain Rates ◽  
Peak Strain ◽  
Stress Strain Curve ◽  
Toughness Index

An improved hydraulic servo structure testing machine has been used to conduct biaxial dynamic compression tests on eight types of engineered cementitious composites (ECC) with lateral pressure levels of 0, 0.125, 0.25, 0.5, 0.7, 0.8, 0.9, 1.0 (the ratio of the compressive strength applied laterally to the static compressive strength of the specimen), and three strain rates of 10−4, 10−3 and 10−2 s−1. The failure mode, peak stress, peak strain, deformation modulus, stress-strain curve, and compressive toughness index of ECC under biaxial dynamic compressive stress state are obtained. The test results show that the lateral pressure affects the direction of ECC cracking, while the strain rate has little effect on the failure morphology of ECC. The growth of lateral pressure level and strain rate upgrades the limit failure strength and peak strain of ECC, and the small improvement is achieved in elastic modulus. A two-stage ECC biaxial failure strength standard was established, and the influence of the lateral pressure level and peak strain was quantitatively evaluated through the fitting curve of the peak stress, peak strain, and deformation modulus of ECC under various strain rates and lateral pressure levels. ECC’s compressive stress-strain curve can be divided into four stages, and a normalized biaxial dynamic ECC constitutive relationship is established. The toughness index of ECC can be increased with the increase of lateral pressure level, while the increase of strain rate can reduce the toughness index of ECC. Under the effect of biaxial dynamic load, the ultimate strength of ECC is increased higher than that of plain concrete.

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