采样云纹方法作为一种新兴的光学测试技术,利用数字图像处理进行光栅相位分析,可实现低成本、高效率、高精度的物体表面变形计量。该方法能灵活调整采样参数以满足不同场景的测量需求,与扫描电子显微镜(scanning electron microscopy,S...采样云纹方法作为一种新兴的光学测试技术,利用数字图像处理进行光栅相位分析,可实现低成本、高效率、高精度的物体表面变形计量。该方法能灵活调整采样参数以满足不同场景的测量需求,与扫描电子显微镜(scanning electron microscopy,SEM)结合,可以实现变倍视场下的变形分析。开展微尺度下高精度的采样云纹变形场测量,需要轮廓清晰、分布规则的光栅或点阵结构,对光栅制备工艺提出了较高的要求。为进一步拓展采样云纹在微尺度力学测量中的应用,本文介绍了采样云纹法变形测量的基本原理,并且发展了一种基于激光直写光刻的微尺度制栅方法。结合自行研制的高密度光栅,进行了镍基合金GH4169疲劳疲劳失效行为研究,表征了疲劳过程中损伤演化与裂纹闭合效应,研究结果表明采样云纹方法在微尺度变形场测量中具有很好的应用潜力。展开更多
RBOE is a new type of DNAN-based high-energy melt-cast mixed explosive,whose safety under thermal stimulation is significantly affected by heating conditions and venting area of the warhead.Based on the thermal decomp...RBOE is a new type of DNAN-based high-energy melt-cast mixed explosive,whose safety under thermal stimulation is significantly affected by heating conditions and venting area of the warhead.Based on the thermal decomposition reaction characteristics and combustion characteristics of each component of RBOE explosive,the cook-off calculation models of RBOE warhead before and after ignition were established.In addition,closed and vented warheads were designed,as well as fast and slow cook-off test devices.The cook-off characteristics and thermal safety venting area of RBOE warhead were extensively studied.The results showed that the closed RBOE warhead underwent deflagration reaction under both slow and fast cook-off conditions.The calculation result of the shell wall temperature before slow cookoff ignition response of the warhead was 454.06 K,with an error of+1.75%compared to the test result of462.15 K,and the temperature rise rate calculated was in good agreement with the test.The calculated ignition time of RBOE warhead under fast cook-off was 161 s,with an error of+8.8%compared to the test result of 148 s,which verified the accuracy of cook-off model of RBOE warhead before ignition.According to the cook-off calculation model of the warhead after ignition and cook-off test of the vented warhead,it was determined that the thermal safety venting area was 1124.61 mm^(2)for fast cook-off and 530.66 mm~2 for slow cook-off,effectively preventing the reaction of warhead above combustion.Therefore,this study provides a scientific basis for the thermal safety design and evaluation of insensitive warheads.展开更多
Cellular structures,distinguished by their porous characteristics,are frequently adopted in designs aimed at impact isolation,owing to their lightweight attributes and exceptional ability to absorb energy during impac...Cellular structures,distinguished by their porous characteristics,are frequently adopted in designs aimed at impact isolation,owing to their lightweight attributes and exceptional ability to absorb energy during impact events.Lattice structures often rely on plastic deformation to absorb energy.However,in applications such as sports protection and robotic grasping,there exists a requirement for a reusable structure designed to isolate impacts,which can be effectively achieved by three-dimensional flexible lattice structures.In this work,a theoretical calculation method for soft lattice structures is proposed,and in light of this method,a three-dimensional soft lattice structure aimed at isolating impacts has been carefully designed.The predictive theory for the quasistatic mechanical properties,including stiffness and buckling strength for three-dimensional soft lattice structures is described.On the basis of the quasizero stiffness characteristics inherent in body-centered cubic,octahedral,and regular diamond structures,a soft impact isolation structure is designed.The soft structure,fabricated with thermoplastic polyurethane material,demonstrated a peak impact isolation efficiency of 83%,despite possessing a thickness of 24 mm described.The work provides a novel design methodology for three-dimensional soft lattice structures and supports the development of reusable impact isolation structures for applications such as reconfigurable robots and space capture missions.展开更多
Magnesium(Mg)alloys,known for their low density and high specific strength,are widely used in the lightweight design of engineering structures.However,their complex mechanical behaviors,particularly including the cycl...Magnesium(Mg)alloys,known for their low density and high specific strength,are widely used in the lightweight design of engineering structures.However,their complex mechanical behaviors,particularly including the cyclic plasticity,damage,and fatigue failure influenced by dislocation slipping,twinning,detwinning,and their interactions,present significant challenges in ensuring the safety and reliability of Mg alloy components.Addressing these challenges requires a comprehensive understanding of such behaviors and their underlying micro-mechanisms,and the development of reliable constitutive models,damage models,and fatigue life prediction methods.This review highlights recent advancements in these topics by elaborating particularly on the intricate connections between the macroscopic plastic deformation and microscopic mechanisms of Mg alloys,and the initiation and propagation of microcracks and microvoids observed through experimental studies and numerical simulations.We also discuss the progress in the theoretical models that predict the cyclic plasticity and/or fatigue life of Mg alloys.Finally,some topics for future research are suggested.展开更多
The integration of physics-based modelling and data-driven artificial intelligence(AI)has emerged as a transformative paradigm in computational mechanics.This perspective reviews the development and current status of ...The integration of physics-based modelling and data-driven artificial intelligence(AI)has emerged as a transformative paradigm in computational mechanics.This perspective reviews the development and current status of AI-empowered frameworks,including data-driven methods,physics-informed neural networks,and neural operators.While these approaches have demonstrated significant promise,challenges remain in terms of robustness,generalisation,and computational efficiency.We delineate four promising research directions:(1)Modular neural architectures inspired by traditional computational mechanics,(2)physics informed neural operators for resolution-invariant operator learning,(3)intelligent frameworks for multiphysics and multiscale biomechanics problems,and(4)structural optimisation strategies based on physics constraints and reinforcement learning.These directions represent a shift toward foundational frameworks that combine the strengths of physics and data,opening new avenues for the modelling,simulation,and optimisation of complex physical systems.展开更多
The proliferative response of T-cells to autolo-gous non-T-cells is referred to as the autologous mixed lymphocyte reaction (AMLR). Recent studies have suggested that AMLR represents a mechanism of immune regulation i...The proliferative response of T-cells to autolo-gous non-T-cells is referred to as the autologous mixed lymphocyte reaction (AMLR). Recent studies have suggested that AMLR represents a mechanism of immune regulation in vivo. We investigated AMLR in patients with acute- and chronic myeloid leukemia (AML and CML). AMLR was found to be significantly depressed (P<0.001) in AML patients (n=17, cpm=532±95) and CML patients (n=13, cpm=688±99) when compared with that of their healthy HLA-identical siblings serving as controls (n=17, cpm=4152±619 and n=13 cpm=4086±421, respectively). In order to understand the cellular basis of the defective AMLR in patients with AML end CML, we performed mitogen-treated T-cell cultures analysis of T-cell subsets and HLA-Ⅱ antigen detection on monocytes. The results indicated that the defect of AMLR in patients resided at the stimulator monocyte level rather than at the responder T-cell level. Enumeration of monocytes reactive with monoclonal antibody Tu22, which recognizes determinants of HLA-DQ, demonstrated that ML patients had a significantly decreased (P<0.091) number of circulating Tu22+ monocytes when compared with normal controls. These studies suggest that a deficiency of HLA-DQ+ monocytes contributes to the depression of AMLR in ML and possibly underlies the abnormalities of immune response present in this disease.展开更多
Direct numerical simulation of a spatially developing turbulent boundary layer over a compliant wall with anisotropic wall material properties is performed. The Reynolds number varies from 300 to approximately 860 alo...Direct numerical simulation of a spatially developing turbulent boundary layer over a compliant wall with anisotropic wall material properties is performed. The Reynolds number varies from 300 to approximately 860 along the streamwise direction, based on the external flow velocity and the momentum thickness. Eight typical cases are selected for numerical investigation under the guidance of the monoharmonic analysis. The instantaneous flow fields exhibit the traveling wavy motion of the compliant wall, and the frequency-wavenumber power spectrum of wall pressure fluctuation is computed to quantify the mutual influence of the wall compliance and the turbulent flow at different wave numbers. It is shown that the Reynolds shear stress and the pressure fluctuation are generally enhanced by the wall compliance with the parameters considered in the present study. A dynamical decomposition of the skin-friction coefficient is derived, and a new term (CW) appears due to the wall-induced Reynolds shear stress. The influence of the anisotropic compliant wall motion on the turbulent boundary layer through the wall-induced negative Reynolds shear stress is discussed. To elucidate the underlying mechanism, the budget analysis of the Reynolds stresses transportation is further carried out. The impact of the wall compliance on the turbulent flow is disclosed by examining the variations of the diffusion and velocity-pressure correlation terms. It is shown that increase of the Reynolds stresses inside the flow domain is caused by enhancement of the velocity-pressure correlation term, possibly through the long-range influence of the wall compliance on the pressure field, rather than diffusion of the wall-induced Reynolds shear stress into the fluid flow.展开更多
文摘采样云纹方法作为一种新兴的光学测试技术,利用数字图像处理进行光栅相位分析,可实现低成本、高效率、高精度的物体表面变形计量。该方法能灵活调整采样参数以满足不同场景的测量需求,与扫描电子显微镜(scanning electron microscopy,SEM)结合,可以实现变倍视场下的变形分析。开展微尺度下高精度的采样云纹变形场测量,需要轮廓清晰、分布规则的光栅或点阵结构,对光栅制备工艺提出了较高的要求。为进一步拓展采样云纹在微尺度力学测量中的应用,本文介绍了采样云纹法变形测量的基本原理,并且发展了一种基于激光直写光刻的微尺度制栅方法。结合自行研制的高密度光栅,进行了镍基合金GH4169疲劳疲劳失效行为研究,表征了疲劳过程中损伤演化与裂纹闭合效应,研究结果表明采样云纹方法在微尺度变形场测量中具有很好的应用潜力。
基金National Natural Science Foundation of china(Grant No.12402468)。
文摘RBOE is a new type of DNAN-based high-energy melt-cast mixed explosive,whose safety under thermal stimulation is significantly affected by heating conditions and venting area of the warhead.Based on the thermal decomposition reaction characteristics and combustion characteristics of each component of RBOE explosive,the cook-off calculation models of RBOE warhead before and after ignition were established.In addition,closed and vented warheads were designed,as well as fast and slow cook-off test devices.The cook-off characteristics and thermal safety venting area of RBOE warhead were extensively studied.The results showed that the closed RBOE warhead underwent deflagration reaction under both slow and fast cook-off conditions.The calculation result of the shell wall temperature before slow cookoff ignition response of the warhead was 454.06 K,with an error of+1.75%compared to the test result of462.15 K,and the temperature rise rate calculated was in good agreement with the test.The calculated ignition time of RBOE warhead under fast cook-off was 161 s,with an error of+8.8%compared to the test result of 148 s,which verified the accuracy of cook-off model of RBOE warhead before ignition.According to the cook-off calculation model of the warhead after ignition and cook-off test of the vented warhead,it was determined that the thermal safety venting area was 1124.61 mm^(2)for fast cook-off and 530.66 mm~2 for slow cook-off,effectively preventing the reaction of warhead above combustion.Therefore,this study provides a scientific basis for the thermal safety design and evaluation of insensitive warheads.
文摘Cellular structures,distinguished by their porous characteristics,are frequently adopted in designs aimed at impact isolation,owing to their lightweight attributes and exceptional ability to absorb energy during impact events.Lattice structures often rely on plastic deformation to absorb energy.However,in applications such as sports protection and robotic grasping,there exists a requirement for a reusable structure designed to isolate impacts,which can be effectively achieved by three-dimensional flexible lattice structures.In this work,a theoretical calculation method for soft lattice structures is proposed,and in light of this method,a three-dimensional soft lattice structure aimed at isolating impacts has been carefully designed.The predictive theory for the quasistatic mechanical properties,including stiffness and buckling strength for three-dimensional soft lattice structures is described.On the basis of the quasizero stiffness characteristics inherent in body-centered cubic,octahedral,and regular diamond structures,a soft impact isolation structure is designed.The soft structure,fabricated with thermoplastic polyurethane material,demonstrated a peak impact isolation efficiency of 83%,despite possessing a thickness of 24 mm described.The work provides a novel design methodology for three-dimensional soft lattice structures and supports the development of reusable impact isolation structures for applications such as reconfigurable robots and space capture missions.
基金supported by the National Natural Science Foundation of China(Nos.12192210,12192214,11921002,and 12302076)China Postdoctoral Science Foundation(No.2024M761630).
文摘Magnesium(Mg)alloys,known for their low density and high specific strength,are widely used in the lightweight design of engineering structures.However,their complex mechanical behaviors,particularly including the cyclic plasticity,damage,and fatigue failure influenced by dislocation slipping,twinning,detwinning,and their interactions,present significant challenges in ensuring the safety and reliability of Mg alloy components.Addressing these challenges requires a comprehensive understanding of such behaviors and their underlying micro-mechanisms,and the development of reliable constitutive models,damage models,and fatigue life prediction methods.This review highlights recent advancements in these topics by elaborating particularly on the intricate connections between the macroscopic plastic deformation and microscopic mechanisms of Mg alloys,and the initiation and propagation of microcracks and microvoids observed through experimental studies and numerical simulations.We also discuss the progress in the theoretical models that predict the cyclic plasticity and/or fatigue life of Mg alloys.Finally,some topics for future research are suggested.
基金supported by the Australian Research Council(Grant No.IC190100020)the Australian Research Council Indus〓〓try Fellowship(Grant No.IE230100435)the National Natural Science Foundation of China(Grant Nos.12032014 and T2488101)。
文摘The integration of physics-based modelling and data-driven artificial intelligence(AI)has emerged as a transformative paradigm in computational mechanics.This perspective reviews the development and current status of AI-empowered frameworks,including data-driven methods,physics-informed neural networks,and neural operators.While these approaches have demonstrated significant promise,challenges remain in terms of robustness,generalisation,and computational efficiency.We delineate four promising research directions:(1)Modular neural architectures inspired by traditional computational mechanics,(2)physics informed neural operators for resolution-invariant operator learning,(3)intelligent frameworks for multiphysics and multiscale biomechanics problems,and(4)structural optimisation strategies based on physics constraints and reinforcement learning.These directions represent a shift toward foundational frameworks that combine the strengths of physics and data,opening new avenues for the modelling,simulation,and optimisation of complex physical systems.
文摘The proliferative response of T-cells to autolo-gous non-T-cells is referred to as the autologous mixed lymphocyte reaction (AMLR). Recent studies have suggested that AMLR represents a mechanism of immune regulation in vivo. We investigated AMLR in patients with acute- and chronic myeloid leukemia (AML and CML). AMLR was found to be significantly depressed (P<0.001) in AML patients (n=17, cpm=532±95) and CML patients (n=13, cpm=688±99) when compared with that of their healthy HLA-identical siblings serving as controls (n=17, cpm=4152±619 and n=13 cpm=4086±421, respectively). In order to understand the cellular basis of the defective AMLR in patients with AML end CML, we performed mitogen-treated T-cell cultures analysis of T-cell subsets and HLA-Ⅱ antigen detection on monocytes. The results indicated that the defect of AMLR in patients resided at the stimulator monocyte level rather than at the responder T-cell level. Enumeration of monocytes reactive with monoclonal antibody Tu22, which recognizes determinants of HLA-DQ, demonstrated that ML patients had a significantly decreased (P<0.091) number of circulating Tu22+ monocytes when compared with normal controls. These studies suggest that a deficiency of HLA-DQ+ monocytes contributes to the depression of AMLR in ML and possibly underlies the abnormalities of immune response present in this disease.
基金the National Natural Science Foundation of China (Grants 11772172 and 11490551).
文摘Direct numerical simulation of a spatially developing turbulent boundary layer over a compliant wall with anisotropic wall material properties is performed. The Reynolds number varies from 300 to approximately 860 along the streamwise direction, based on the external flow velocity and the momentum thickness. Eight typical cases are selected for numerical investigation under the guidance of the monoharmonic analysis. The instantaneous flow fields exhibit the traveling wavy motion of the compliant wall, and the frequency-wavenumber power spectrum of wall pressure fluctuation is computed to quantify the mutual influence of the wall compliance and the turbulent flow at different wave numbers. It is shown that the Reynolds shear stress and the pressure fluctuation are generally enhanced by the wall compliance with the parameters considered in the present study. A dynamical decomposition of the skin-friction coefficient is derived, and a new term (CW) appears due to the wall-induced Reynolds shear stress. The influence of the anisotropic compliant wall motion on the turbulent boundary layer through the wall-induced negative Reynolds shear stress is discussed. To elucidate the underlying mechanism, the budget analysis of the Reynolds stresses transportation is further carried out. The impact of the wall compliance on the turbulent flow is disclosed by examining the variations of the diffusion and velocity-pressure correlation terms. It is shown that increase of the Reynolds stresses inside the flow domain is caused by enhancement of the velocity-pressure correlation term, possibly through the long-range influence of the wall compliance on the pressure field, rather than diffusion of the wall-induced Reynolds shear stress into the fluid flow.
