An experimental study on degeneration of the coldworking residual strainduring different cyclic loadings is presented. The expenmental results obtained showthat the residual strain of squcezing dislributes under power...An experimental study on degeneration of the coldworking residual strainduring different cyclic loadings is presented. The expenmental results obtained showthat the residual strain of squcezing dislributes under power series law ε= axb overthe horizontal line of the stress on both sides of the cenual hole. and that when the max-imum real stress at the hole is lower than the yield stress of the material. the degeneration of residual strain has a sudden change during cyclic loading, and the closer to thehole side, the more serious the degcneration.展开更多
With hot rolling in laboratory and Gleeble thermal simulator, the hot working of a high nitrogen austenitic stainless steel （HNASS） was researched. The results showed that dynamic recovery （DRV） and dynamic recrys...With hot rolling in laboratory and Gleeble thermal simulator, the hot working of a high nitrogen austenitic stainless steel （HNASS） was researched. The results showed that dynamic recovery （DRV） and dynamic recrystalli- zation （DRX） in HNASS occurred during hot working, and both of them had well-defined stress peaks in flow curves under different conditions. During hot rolling experiment at temperature from 950 to 1 050 ℃, recrystallization phe- nomenon does not take place in test material until the deformation ratio is up to 40%. Recrystallization influences remarkably the strength and ductility of material, and the test HNASS possesses better combination of strength with ductility. According to the curve of θ--α （strain hardening rate-steady state stress）, the DRX critical strain of test material was determined. Also, the activation energy of hot working was calculated to be 746.5 kJ/mol and the equation of hot working was obtained.展开更多
The mechanical properties of the TWIP steel subjected to impact loading at various strain rates were analyzed by the split Hopkinson pressure bar. Meanwhile the microstructure of the TWIP steel fore-and-aft dynamic de...The mechanical properties of the TWIP steel subjected to impact loading at various strain rates were analyzed by the split Hopkinson pressure bar. Meanwhile the microstructure of the TWIP steel fore-and-aft dynamic deformation was oberseved and analyzed by optical microscope （OM）, X-ray diffraction （XRD）, and transmission electron microscope （TEM）. The results show that when the TWIP steel was deformed under dynamic condition, the stress, microhardness and work hardening rate increase with the increase of strain and strain rate; there is decline of work hardening rate for adiabatic temperature rising softening. There are many pin-like deformation twins in the microstructure of the TWIP steel subjected to impact loading, and the grain size after deformation is bigger than that before; the interaction of twins with dislocation and twins with twins, especially emergence of multiple deformation twins are the main strengthening mechanisms of the TWIP steel. The nucleation mechanism of deformation twins will be ＂rebound mechanism＂;the incomplete deformation twins can be observed when the strain rate is low; when strain rate increases, deformation twins unite together;and deformation twins become denser because the nucleation rate increases with increasing the strain rate.展开更多
Deformation behaviors of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloys with α/β lamellar structure were investigated systematically at different temperatures from room temperature to 950 ~C and different strain rates. Results r...Deformation behaviors of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloys with α/β lamellar structure were investigated systematically at different temperatures from room temperature to 950 ~C and different strain rates. Results reveal that when the deformation temperature is higher than a critical temperature of 600℃, an evident transition of deformation behavior from localized shear banding to α/β lamella kinking, flow softening and temperature/strain rate-dependent peak flow stress occurred in the alloy. The critical conditions for the occurrence of internal cracking and strain localization behavior associated with temperature and strain rate were determined.展开更多
The ultrasound pressure-strain loop (PSL) technique is a non-invasive method of examining myocardial work, which takes into account the effect of cardiac afterload on deformation and combines the overall longitudinal ...The ultrasound pressure-strain loop (PSL) technique is a non-invasive method of examining myocardial work, which takes into account the effect of cardiac afterload on deformation and combines the overall longitudinal strain force of the left ventricle with the changes in the left ventricular pressure, allowing earlier detection of possible subclinical cardiac damage in patients, and a more accurate and non-invasive assessment of the patient’s myocardial work performance. In this article, we will discuss the progress of PSL applications in cardiovascular diseases.展开更多
Due to advances in modern tumor treatments, patients can survive long-term. However, cardiotoxicity caused by tumor therapy poses a significant challenge to both physicians and patients. Early detection and accurate a...Due to advances in modern tumor treatments, patients can survive long-term. However, cardiotoxicity caused by tumor therapy poses a significant challenge to both physicians and patients. Early detection and accurate assessment of cardiovascular toxicity from tumor therapy are crucial for guiding clinical treatment and improving patient prognosis. A noninvasive myocardial workup can monitor and assess the development of tumor chemotherapy-related cardiotoxicity. In monitoring oncology chemotherapy-related cardiac injury, a significant decrease in left ventricular ejection fraction (LVEF) of left ventricular systolic function (LVSCF) often indicates severe cardiac injury, making it challenging to monitor early cardiac injury. 3D-STI (three-dimensional speckle tracking imaging) can evaluate early cardiac injury, but its load dependence reduces the accuracy of myocardial function evaluation. In contrast, the noninvasive evaluation of myocardial work using left ventricular pressure-strain loops (PSL), which considers both myocardial deformation and left ventricular pressure, avoids the effect of load dependence on myocardial contractile function and improves the accuracy of myocardial function evaluation. This article reviews the noninvasive evaluation of myocardial work to assess cardiotoxicity associated with tumor chemotherapy.展开更多
文摘An experimental study on degeneration of the coldworking residual strainduring different cyclic loadings is presented. The expenmental results obtained showthat the residual strain of squcezing dislributes under power series law ε= axb overthe horizontal line of the stress on both sides of the cenual hole. and that when the max-imum real stress at the hole is lower than the yield stress of the material. the degeneration of residual strain has a sudden change during cyclic loading, and the closer to thehole side, the more serious the degcneration.
基金Item Sponsored by National Basic Research Program of China(2004CB619103)
文摘With hot rolling in laboratory and Gleeble thermal simulator, the hot working of a high nitrogen austenitic stainless steel （HNASS） was researched. The results showed that dynamic recovery （DRV） and dynamic recrystalli- zation （DRX） in HNASS occurred during hot working, and both of them had well-defined stress peaks in flow curves under different conditions. During hot rolling experiment at temperature from 950 to 1 050 ℃, recrystallization phe- nomenon does not take place in test material until the deformation ratio is up to 40%. Recrystallization influences remarkably the strength and ductility of material, and the test HNASS possesses better combination of strength with ductility. According to the curve of θ--α （strain hardening rate-steady state stress）, the DRX critical strain of test material was determined. Also, the activation energy of hot working was calculated to be 746.5 kJ/mol and the equation of hot working was obtained.
基金Item Sponsored by Scientific Research Plan of Shanxi Province of China(20090321072)
文摘The mechanical properties of the TWIP steel subjected to impact loading at various strain rates were analyzed by the split Hopkinson pressure bar. Meanwhile the microstructure of the TWIP steel fore-and-aft dynamic deformation was oberseved and analyzed by optical microscope （OM）, X-ray diffraction （XRD）, and transmission electron microscope （TEM）. The results show that when the TWIP steel was deformed under dynamic condition, the stress, microhardness and work hardening rate increase with the increase of strain and strain rate; there is decline of work hardening rate for adiabatic temperature rising softening. There are many pin-like deformation twins in the microstructure of the TWIP steel subjected to impact loading, and the grain size after deformation is bigger than that before; the interaction of twins with dislocation and twins with twins, especially emergence of multiple deformation twins are the main strengthening mechanisms of the TWIP steel. The nucleation mechanism of deformation twins will be ＂rebound mechanism＂;the incomplete deformation twins can be observed when the strain rate is low; when strain rate increases, deformation twins unite together;and deformation twins become denser because the nucleation rate increases with increasing the strain rate.
基金supported by the National Basic Research Program of China(No.2007CB613803)the National Natural Science Foundation of China(NSFC,No.51071158)partially supported by the NSFC(No.51171045)
文摘Deformation behaviors of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloys with α/β lamellar structure were investigated systematically at different temperatures from room temperature to 950 ~C and different strain rates. Results reveal that when the deformation temperature is higher than a critical temperature of 600℃, an evident transition of deformation behavior from localized shear banding to α/β lamella kinking, flow softening and temperature/strain rate-dependent peak flow stress occurred in the alloy. The critical conditions for the occurrence of internal cracking and strain localization behavior associated with temperature and strain rate were determined.
文摘The ultrasound pressure-strain loop (PSL) technique is a non-invasive method of examining myocardial work, which takes into account the effect of cardiac afterload on deformation and combines the overall longitudinal strain force of the left ventricle with the changes in the left ventricular pressure, allowing earlier detection of possible subclinical cardiac damage in patients, and a more accurate and non-invasive assessment of the patient’s myocardial work performance. In this article, we will discuss the progress of PSL applications in cardiovascular diseases.
文摘Due to advances in modern tumor treatments, patients can survive long-term. However, cardiotoxicity caused by tumor therapy poses a significant challenge to both physicians and patients. Early detection and accurate assessment of cardiovascular toxicity from tumor therapy are crucial for guiding clinical treatment and improving patient prognosis. A noninvasive myocardial workup can monitor and assess the development of tumor chemotherapy-related cardiotoxicity. In monitoring oncology chemotherapy-related cardiac injury, a significant decrease in left ventricular ejection fraction (LVEF) of left ventricular systolic function (LVSCF) often indicates severe cardiac injury, making it challenging to monitor early cardiac injury. 3D-STI (three-dimensional speckle tracking imaging) can evaluate early cardiac injury, but its load dependence reduces the accuracy of myocardial function evaluation. In contrast, the noninvasive evaluation of myocardial work using left ventricular pressure-strain loops (PSL), which considers both myocardial deformation and left ventricular pressure, avoids the effect of load dependence on myocardial contractile function and improves the accuracy of myocardial function evaluation. This article reviews the noninvasive evaluation of myocardial work to assess cardiotoxicity associated with tumor chemotherapy.
