Normal Strain Rate Research Articles

Effect of Solution Heat Treatment on the Hot Workability of Al–Mg–Si Alloy

The current work presents a detailed study on the high temperature processing of solution treated Al–Mg–Si alloy in the temperature range of 623 K to 773 K and at different strain rates in the range of 5 × 10−5 to 6 × 10−2 s−1. A constitutive relation that can be used in modeling the forming process of this alloy under similar hot working conditions is established. Also, the prevailing deformation mechanism was investigated through relations of the steady state stress dependence on strain rate which revealed a stress exponent of 8.5 (strain rate sensitivity; m ∼ 0.12). This stress exponent is higher than what is usually observed in Al and Al–Mg alloys under similar experimental conditions. This high stress exponent may arise from the presence of threshold stress that results from dislocation interaction with second phase particles (Mg2Si), precipitating during the deformation at high temperatures. The values of threshold stress showed an exponential increase with decreasing temperature and a dependence with an energy term Qo = 38 kJmol−1. The apparent activation energy for solution treated condition was calculated to be about 320 kJmol−1, which is higher than the activation energy for self-diffusion in Al (Qd = 143 kJmol−1) and for the diffusion of Mg in Al (115–130 kJmol−1). By incorporating the threshold stress in the analysis, the true activation energy was calculated to have a value of 111 kJmol−1, and the normalized strain rates can be represented by a power function of the effective stress with stress exponent of ∼3. Ductility was documented to reveal the best working condition for this alloy in solution treated condition. The ductility exhibited a maximum value of about 120% at 773 K at a strain rate of 0.064 s−1. The results of the current work is, also, compared to the results of another heat treatment condition (T4-naturally aged) to reveal which ever condition holds better hot forming characteristics.

Deformation mechanisms in Cr20Ni80 alloy at elevated temperatures

The mechanisms of plastic deformation of Cr20Ni80 nichrome with an initial grain size of 80 μm were studied in the temperature range 600–950°C and the strain-rate range 1.5 × 10−6−5 × 10−2s−1. Nichrome is shown to exhibit anomalously high values of stress exponent n and a high deformation activation energy Q. These unusual properties were found to be caused by “threshold” stresses below which deformation does not occur. An analysis of the deformation behavior with allowance for threshold stresses reveals the regions of hot, warm, and cold deformation in nichrome. At normalized strain rates $$ \dot \varepsilon $$ kT/D 1 Gb < 10−8, the true values of n and Q are ∼4 and 285 ± 30 kJ/mol, respectively. In the normalized-strain range 10−8−10−4 n ∼ 6 and the deformation activation energy decreases to 175 ± 30 kJ/mol. This change in the deformation-behavior characteristics is explained by the transition from high-temperature dislocation climb, which is controlled by lattice self-diffusion, to low-temperature dislocation climb, which is controlled by pipe diffusion, as the temperature decreases. At $$ \dot \varepsilon $$ kT/D 1 Gb = 10−4, a power law break-down takes place and an exponential law (which describes the deformation behavior in the range of cold deformation) becomes operative.

Effects of Lewis number on the reactive scalar gradient alignment with local strain rate in turbulent premixed flames

The effects of Lewis number Le on the reactive scalar gradient alignment with the local strain rate have been studied using Direct Numerical Simulation data of freely propagating statistically planar turbulent premixed flames with Le ranging from 0.34 to 1.2. The alignment characteristics of the reaction progress variable gradient are explained using the statistics of dilatation rate, and flame normal and tangential strain rates. The strength of dilatation rate is shown to increase with decreasing Le and this effect becomes particularly strong for the flames with Le<1 because of thermo-diffusive instability. The dilatation rate is shown to be responsible for the preferential alignment of the reactive scalar gradient with the most extensive principal strain rate in the reaction zone for flames with Le close to unity, contrary to the alignment of scalar gradient with the most compressive principal strain rate in turbulent passive scalar transport. However, stronger dilatation rate effects in Le≪1 flames (e.g. Le=0.34) gives rise to the preferential alignment of the reactive scalar gradient with the most extensive principal strain rate for the major portion of the flame-brush. The scalar gradient alignment with local strain rate plays an important role in the transport of scalar dissipation rate and the flame surface density. The observed alignment with the most extensive principal strain rate destroys the scalar gradient and the magnitude of this sink is found to increase with decreasing Lewis number for a given turbulent Reynolds number and Damköhler number.

Hot deformation of AA6082-T4 aluminum alloy

High-temperature tensile deformation of 6082-T4 Al alloy was conducted in the range of 623–773 K at various strain rates in the range of 5 × 10−5 to 2 × 10−2 s−1. Stress dependence of the strain rate revealed a stress exponent, n of 7 throughout the ranges of temperatures and strain rates tested. This stress exponent is higher than what is usually observed in Al–Mg alloys under similar experimental conditions, which implies the presence of threshold stress. This behavior results from dislocation interaction with second phase particles (Mg2Si). The experimental threshold stress values were calculated, based on the finding that creep rate is viscous glide controlled, based on creep tests conducted on binary Al–1Mg at 673 K, that gave n a value of 3. The threshold stress (σo) values were seen to decrease exponentially with temperature. The apparent activation energy for 6082-T4 was calculated to be about 245 kJ mol−1, which is higher than the activation energy for self-diffusion in Al (Qd = 143 kJ mol−1) and for the diffusion of Mg in Al (115–130 kJ mol−1). By incorporating the threshold stress in the analysis, the true activation energy was calculated to be about 107 kJ mol−1. Analysis of strain rate dependence in terms of the effective stress (σ − σo) using normalized parameters, revealed a single type of deformation behavior. A plot of normalized strain rate (\( \dot{\varepsilon }kT/DGb \)) versus normalized effective stress (σ − σo)/G, on a double logarithmic scale, gave an n value of 3.

High-Temperature Deformation and Ductility of a Modified 5083 Al Alloy

The high-temperature deformation of a 5.5% Mg and 0.6% Ca modified 5083 aluminum alloy was investigated in the temperature range from 573 to 723 K at strain rates in the range of 10−5-10−1 s−1. Ca was added to form an insoluble second phase in the range of temperatures tested to improve the high-temperature characteristics of this alloy. It was shown that the deformation behavior of the alloy could be divided into two regions with stress exponent, n of 3.5 and 13 at low and high strain rates, respectively. The apparent activation energy determined in both regions suggested that the deformation process is diffusion controlled in both regions. The slightly high value of n at the low-strain rate region (viscous glide) was attributed to the presence of threshold stress. The values of threshold stress showed an exponential increase with decreasing temperature and a dependence with an energy term Qo = 16.5 kJ mol−1. Analysis of creep data in terms of threshold stress and using diffusivity of Mg in normalizing the strain rates, revealed two types of deformation behavior. At high values of normalized strain rate $$ ({\ifmmode\expandafter\dot\else\expandafter\.\fi{\upvarepsilon }kT} \mathord{\left/ {\vphantom {{\ifmmode\expandafter\dot\else\expandafter\.\fi{\varepsilon }kT} {DGb}}} \right. \kern-\nulldelimiterspace} {DGb} > 10^{{ - 9}} ), $$ a high value of stress exponent of n = 10 is observed, and the exponential law creep takes place. At low normalized strain rates ≤10−9, the n value is 3 and the true activation energy, Q, is equal to 123 kJ mol−1 suggesting viscous glide of dislocations as rate-controlling mechanism. Enhanced ductility has been observed in the region of viscous-glide controlled deformation as a result of high strain-rate sensitivity.

High strength and high ductility of electrodeposited nanocrystalline Ni with a broad grain size distribution

A nanocrystalline nickel with a broad grain size distribution was prepared by direct current electrodeposition, which exhibited high ultimate strength of 1440–1916 MPa and good ductility of 5.6–11.3% under tensile test at a wide strain rate range (1.35E−6 to 1.35 s −1) and room temperature. The good ductility of nc Ni can be attributed to the increased strain hardening ability induced by the inhomogeneous microstrucutre. Two distinguished strain rate sensitivity (0.016 and 0.045) and flow stress activation volume (26 b 3 and 11 b 3) were obtained at normal and high strain rate and low strain rate, respectively. The intrinsic microstructure and extrinsic deformation conditions (low strain rate) lead to the transition in the deformation mechanism from the dislocation mediated deformation to both grain boundary and dislocation deformation with decreasing strain rate. The high near-uniform elongation at low strain rate can be explained by its corresponding high m value. The variation of fracture surface morphology with strain rates also implies the underlying deformation mechanism transition.

Biofluid mechanical investigations in sequencing batch reactor (SBR)

In the present contribution experimental and numerical investigations of multiphase flow in a sequencing batch reactor (SBR) are presented. In the bioreactor the formation and growth of granular activated sludge (GAS) with diameter up to 5 mm occurs. In order to experimentally analyse multiphase flow patterns in a mixture of water, air and granules in the SBR, optical in situ techniques are applied. Particle image velocimetry (PIV) and particle tracking velocimetry (PTV) are employed to observe the velocity fields of fluid and granules. For the three-dimensional numerical simulation of the flow problem the Euler–Euler approach is used. The comparison of experimental and numerical results shows a lot of similarities. The characteristic flow patterns can be observed in three zones of the SBR. It can be shown that effect of normal strain rate up to ε ˙ = 15 s - 1 and shear strain rate up to γ ˙ = 15 s - 1 , besides biochemical activities have a major influence on the formation, shape and size of the granules in the SBR under aerobic conditions.

Effects of Atomic Hydrogen and Flaking on Mechanical Properties of Wheel Steel

The effects of atomic hydrogen and flaking on the strength, plasticity, fracture toughness, and hydrogen-induced delayed cracking (HIDC) of a wheel steel were investigated. The results showed that the critical diffusible (C 0 * ) or total (C * ) hydrogen concentration for forming flaking were C 0 * = 1.3 ppm and C * = 3.7 ppm, respectively. There was no effect of flaking on the strength, plasticity, and fracture toughness if the amount of flaking was low, e.g., diffusible hydrogen concentration C 0 ≤ 3.9 ppm. Atomic hydrogen had no effect on the fracture toughness and the mechanical properties extended with normal strain rate. Atomic hydrogen, however, had the effect of reducing the plasticity during slow strain rate tests and induced delayed failure under constant displacement. The threshold stress intensity factor of HIDC, K IH, decreased linearly with the diffusible hydrogen concentration C 0, i.e., K IH(MPam1/2) = K IC − 3.6C 0 (ppm) (0.2 ≤ C 0 ≤ 03.9). The HIDC could be partly attributed to hydrogen-induced additive stress. There was no effect of flaking on HIDC.

Limits on rock strength under high confinement

Abstract Understanding of deep earthquake source mechanisms requires knowledge of failure processes active under high confinement. Under low confinement the compressive strength of rock is well known to be limited by frictional sliding along stress-concentrating flaws. Under higher confinement strength is usually assumed limited by power-law creep associated with the movement of dislocations. In a review of existing experimental data, we find that when the confinement is high enough to suppress frictional sliding, rock strength increases as a power–law function only up to a critical normalized strain rate. Within the regime where frictional sliding is suppressed and the normalized strain rate is below the critical rate, both globally distributed ductile flow and localized brittle-like failure are observed. When frictional sliding is suppressed and the normalized strain rate is above the critical rate, failure is always localized in a brittle-like manner at a stress that is independent of the degree of confinement. Within the high-confinement, high-strain rate regime, the similarity in normalized failure strengths across a variety of rock types and minerals precludes both transformational faulting and dehydration embrittlement as strength-limiting mechanisms. The magnitude of the normalized failure strength corresponding to the transition to the high-confinement, high-strain rate regime and the observed weak dependence of failure strength on strain rate within this regime are consistent with a localized Peierls-type strength-limiting mechanism. At the highest strain rates the normalized strengths approach the theoretical limit for crystalline materials. Near-theoretical strengths have previously been observed only in nano- and micro-scale regions of materials that are effectively defect-free. Results are summarized in a new deformation mechanism map revealing that when confinement and strain rate are sufficient, strengths approaching the theoretical limit can be achieved in cm-scale sized samples of rocks rich in defects. Thus, non-frictional failure processes must be considered when interpreting rock deformation data collected under high confinement and low temperature. Further, even at higher temperatures the load-bearing ability of crustal rocks under high confinement may not be limited by a frictional process under typical geologic strain rates.

Influence of the Damköhler number on turbulence-scalar interaction in premixed flames. I. Physical insight

Scalar dissipation rate is a central quantity in turbulent flame modeling as it is closely related to the reaction rate. It is well known that turbulence-scalar interaction plays a vital role in turbulent flows with scalar mixing and thus on the scalar dissipation rate. This interaction process is characterized by the tensor inner product between the scalar gradient vector and the turbulence strain rate tensor and it is found to depend strongly on the Damköhler number, Da. Two direct numerical simulation data sets are analyzed in detail in order to understand the physics of Da dependence. The well known alignment of scalar gradient with the most compressive principal strain rate resulting in production of the scalar gradient by turbulence is observed for low (Da&amp;lt;1) Damköhler number flame, whereas the turbulence dissipates the scalar gradient in high Da flame. This dissipation of the scalar gradient in the high Da flame is because of its preferential alignment with the most extensive principal strain rate. Even for Da&amp;lt;1 flame, in the regions of intense heat release the scalar gradient has a tendency to align with the most extensive strain rate. This distinct change is because of strong competition between chemical strain rate, due to dilatation from the flame front and the local fluid dynamic strain rate. The alignment characteristics affect flame normal and tangential strain rate statistics. The flame normal strain rate is found to be positive throughout the flame brush when Da&amp;gt;1, whereas it is predominantly negative when Da&amp;lt;1. Despite this difference the mean tangential strain rate remains positive yielding flame surface area production. However, the production results via different physical mechanisms. Possible implications of these differences on the modeling of turbulent premixed flames are identified and explained.

Effect of trabecular bone loss on cortical strain rate during impact in an in vitro model of avian femur

BackgroundOsteoporotic hip fractures occur due to loss of cortical and trabecular bone mass and consequent degradation in whole bone strength. The direct cause of most fractures is a fall, and hence, characterizing the mechanical behavior of a whole osteopenic bone under impact is important. However, very little is known about the mechanical interactions between cortical and trabecular bone during impact, and it is specifically unclear to what extent epiphyseal trabecular bone contributes to impact resistance of whole bones. We hypothesized that trabecular bone serves as a structural support to the cortex during impact, and hence, loss of a critical mass of trabecular bone reduces internal constraining of the cortex, and, thereby, decreases the impact tolerance of the whole bone.MethodsTo test this hypothesis, we conducted cortical strain rate measurements in adult chicken's proximal femora subjected to a Charpy impact test, after removing different trabecular bone core masses to simulate different osteopenic severities.ResultsWe found that removal of core trabecular bone decreased by ~10-fold the cortical strain rate at the side opposite to impact (p < 0.01), i.e. from 359,815 ± 1799 μm/m per second (mean ± standard error) for an intact (control) specimen down to 35,997 ± 180 μm/m per second where 67% of the total trabecular bone mass (~0.7 grams in adult chicken) were removed. After normalizing the strain rate by the initial weight of bone specimens, a sigmoid relation emerged between normalized strain rate and removed mass of trabecular bone, showing very little effect on the cortex strain rate if below 10% of the trabecular mass is removed, but most of the effect was already apparent for less than 30% trabecular bone loss. An analytical model of the experiments supported this behavior.ConclusionWe conclude that in our in vitro avian model, loss of over 10% of core trabecular bone substantially altered the deformation response of whole bone to impact, which supports the above hypothesis and indicates that integrity of trabecular bone is critical for resisting impact loads.

Myocardial Infarction as a Rare Consequence of a Snakebite

A healthy 28-year-old man with no history of cardiac disease and no cardiac risk factors presented to the hospital 2 hours after being bitten on his right hand by his pet snake. He was in anaphylactic shock and was rapidly resuscitated with fluids, inotropic support, intramuscular antitetanus serum, and intravenous infusion of Viper-FAB, an antidote. His vital signs normalized and he was admitted to intensive care for further observation. One hour after admission, the patient’s systolic blood pressure dropped to 40 mm Hg. Intravenous noradrenaline was started. Thirty minutes later, the patient lost consciousness in association with a rhythm change to torsade de pointes. He was defibrillated with 100 J (biphasic defibrillator) to sinus rhythm. Intravenous magnesium was started, and a repeat 12-lead ECG showed a prolonged corrected QT interval at 490 ms with no ST elevation (Figure 1). An urgent echocardiogram demonstrated normal-sized left ventricle with mild hypokinesis of the anterior wall and a global left ventricular fraction of 60%. Tissue Doppler images acquired by Vivid-7 (GE Medical) …

Effects of strain rate and curvature on surface density function transport in turbulent premixed flames in the thin reaction zones regime

Strain rate and curvature effects on Surface Density Function (SDF) transport in the thin reaction zones regime are studied using a three-dimensional direct numerical simulations (DNS) with a single-step Arrhenius type chemistry. It is shown that if the tangential strain rate on a flame isosurface exceeds a critical value, then a negative normal strain rate is induced, which acts to bring the isoscalar lines closer to each other and hence leads to a higher value of SDF. This is reflected in a positive correlation between SDF and tangential strain rate. Curvature is also found to affect SDF through the correlation between tangential strain rate and curvature on a given flame isosurface. Strain rate and curvature are found to have an appreciable effect on various terms of the SDF transport equation. The SDF straining term is correlated positively with tangential strain rate as expected and is also correlated negatively with the curvature. The combined SDF curvature and propagation terms operate as a source near the fresh gas side of the flame and as a sink towards the burned gas side. The SDF propagation term is found to correlate negatively with flame curvature towards the fresh gas side and positively towards the burned gas side. The variation of the SDF curvature term with local flame curvature is found to be nonlinear due to the additional stretch induced by the tangential diffusion component of the displacement speed.

Formation of persistent dislocation loops by ultra-high strain-rate deformation during cold spraying

Pure copper was deformed at ultra-high strain-rates by the technique of cold spraying. It was found that after annealing the hardness of the samples does not fall as low as is known for heavily deformed copper at normal strain rates, e.g., cold rolling. The reason for this is the presence of defects that do not heal out after annealing at 600 °C. These defects were identified as dislocation loops of the extrinsic and intrinsic kind. Possible mechanisms for the formation of these loops are discussed.

Deformation behavior of a modified 5083 aluminum alloy

The deformation behavior of a 0.2% Zr and 1.6% Mn modified 5083 aluminum alloy was studied in the temperature range of 250–570 °C over seven orders of magnitude of strain rates. It was shown that the modified 5083 alloy exhibits threshold behavior in the temperature interval of 250–500 °C. There exists a temperature dependence of threshold stress with the energy term Q o = 18 kJ/mol. It was shown by transmission election microscopy that detachment of dislocations from dispersoids under extra force takes place. Threshold stress tends to disappear with increasing temperature at T > 500 °C despite the fact that evidence for interactions between mobile dislocations and dispersoids was found at these temperatures. Analysis of creep data in terms of threshold stress revealed three different types of deformation behavior. At high values of normalized strain rate, ε ˙ k T / ( D 1 G b ) > 4 × 10 − 8 , the exponential law creep takes place. At normalized strain rates, ε ˙ k T / ( D 1 G b ) , ranging from 4 × 10 −8 to 4 × 10 −14, the n value is ∼4 and the true activation energy, Q c, is equal to 139 ± 12 kJ/mol, suggesting high temperature dislocation climb. At low normalized strain rate, a transition to Newtonian viscous flow occurs.

What indices quantify regional myocardial function during supine bicycle in healthy subject: natural strain and strain rate?

Background Evaluation and quantification of regional myocardial function remain a challenge for imaging techniques in stress test. Strain and strain rate can be calculated from velocity gradients in time and space. This new technique has been developed to allow quantifiable stress echocardiography. The aim of this study was to define normal regional strain rate and strain values for both radial and deformation longitudinal myocardial deformation during supine bicycle. Methods Real-time color Doppler myocardial velocities were acquired as data superimposed on an underlying two-dimensional (2D) grey-scale image at a frame rate >150/s, a depth of 16 cm, and a sector angle of 60° in 18 healthy volunteers, mean age 34±7 years (25–43 years). During acquisition, a complete cardiac cycle of each view was acquired at rest and during supine bicycle (from 25 W to maximal charge). Maximal systolic velocity, strain rate, and strain were processed offline for both radial (basal posterior wall segment) and longitudinal (septum, lateral, inferior, anterior walls) function. For analysis, each wall was divided into three segments (basal, mid, apical). All the velocity and SR/ S values were averaged over three consecutive cycles. Results During exercise, heart rate and systolic blood pressure increased significantly from rest to peak stress (69±14 vs. 152±7 beats/min, p<0.0001 and 118±9 vs. 178±28 mm Hg, p<0.001). For the Lax view, both the mean velocity and mean strain rate increased significantly between rest and peak exercise, respectively, for the velocity and for the strain rate. Similarly is said for the Sax view. In contrast, the systolic strain response was biphasic during exercise, basal, mid, and apical segments of walls showed a significant increase of velocity in each workload step. The resting base–apex velocity gradient observed at rest remained in all walls throughout supine bicycle. The mean peak systolic SR data were homogeneous throughout in all segments analysed at rest. This homogeneity remained at peak exercise. The SR increased significantly between rest and peak exercise, respectively, p<0.0117. The segmental systolic strain response was biphasic. Conclusion This study demonstrated that strain rate imaging may represent a new and interesting method for quantifying regional myocardial function during supine bicycle, which appears to be less influenced by tethering than Doppler tissue imaging. Further studies are needed to determine whether this approach will be clinically useful.

Simultaneous PLIF/PIV investigation of vortex-induced annular extinction in H 2 -air counterflow diffusion flames

High-temporal-resolution measurements of scalars and velocity are used to study vortex-induced annular (off-centerline) flame extinction during the interaction of a propagating vortex with an initially stationary counterflow hydrogen-air diffusion flame. Such an extinction process differs from classical one-dimensional descriptions of strained flamelets in that it captures the effects of flame curvature as well as dynamic strain. Planar laser-induced fluorescence (PLIF) measurements of the hydroxyl radical (OH) are used to track flame development, and simultaneous particle-image velocimetry (PIV) is used to characterize the two-dimensional flowfield. Measurements reveal differences in local normal strain rate profiles along and across the reaction zone and indicate that vortex-induced curvature in the annular region may initiate the extinction process. In addition, the effect of local flame extinction on vortex evolution and dissipation is determined from measured vorticity data.

Comparison of microstructures in electroformed copper liners of shaped charges before and after plastic deformation at different strain rates

Transmission electron microscopy observations of the recovered slugs of electroformed copper liner materials that had undergone high-strain-rate deformation show the existence of a wide range of crystal defects, including vacancy clusters and porosity. Cellular structures formed by tangled dislocations and subgrain boundaries consisting of dislocation arrays were also detected. Electron backscattering Kikuchi pattern technique analysis reveals that the fibrous texture observed in the as-formed copper liners of shaped charges disappeared after explosive detonation deformation. In a specimen that had been plastically deformed at a normal strain rate (4×10 −4 s −1), a high density of dislocations was observed within grains. These experimental results indicate that dynamic recovery and recrystallization play an important role during high-strain-rate deformation by virtue of a temperature increase in the deformation process, whereas the conventional slip mechanism operates during deformation at the normal strain rates.

Frictional‐viscous flow of phyllosilicate‐bearing fault rock: Microphysical model and implications for crustal strength profiles

It is widely believed that around the brittle‐ductile transition, crustal faults can be significantly weaker than predicted by conventional two‐mechanism brittle‐ductile strength envelopes. Factors contributing to this weakness include the polyphase nature of natural rocks, foliation development, and the action of fluid‐assisted processes such as pressure solution. Recently, ring shear experiments using halite/kaolinite mixtures as an analogue for phyllosilicate‐rich rocks for the first time showed frictional‐viscous behavior (i.e., both normal stress and strain rate sensitive behavior) involving the combined effects of pressure solution and phyllosilicates. This behavior was accompanied by the development of a mylonitic microstructure. A quantitative assessment of the implications of this for the strength of natural faults has hitherto been hampered by the absence of a microphysical model. In this paper, a microphysical model for shear deformation of foliated, phyllosilicate‐bearing fault rock by pressure solution‐accommodated sliding along phyllosilicate foliae is developed. The model predicts purely frictional behavior at low and high shear strain rates and frictional‐viscous behavior at intermediate shear strain rates. The mechanical data on wet halite + kaolinite gouge compare favorably with the model. When applied to crustal materials, the model predicts major weakening with respect to conventional brittle‐ductile strength envelopes, in particular, around the brittle‐ductile transition. The predicted strength profiles suggest that in numerical models of crustal deformation the strength of high‐strain regions could be approximated by an apparent friction coefficient of 0.25–0.35 down to depths of 15–20 km.

Doppler myocardial imaging. A new tool to assess regional inhomogeneity in cardiac function.

In echocardiography, there is still a need for a better tool to quantify regional myocardial function. Doppler myocardial imaging (DMI) allows the calculation of local myocardial velocity profiles for segmental motion in both the radial and longitudinal direction. From the local velocity profile data, 1-dimensional regional myocardial strain rates (SR) and strain (epsilon) can now be calculated. These new deformation indices more accurately define regional function compared to velocities as they are independent of overall heart motion. This paper will define the normal segmental velocity, SR and epsilon profiles and their relationship with global mechanical event markers. It will also define the changes in local velocity and deformation characteristics, which are induced by disease and the current experimental and clinical status of this new quantitative ultrasound tool.