Theory of particle transport phenomena during fatigue and time-dependent fracture of materials based on mesoscale dynamics and their practical applications

Abstract

In this work, the mesoscale mechanics of metals, which links their microscopic physics and macroscopic mechanics, was established. For practical applications, the laws for quantitatively predicting life of cycle and time-dependent fracture behavior such as fatigue, hydrogen embrittlement, and high-temperature creep were derived using particle transport phenomena theories such as dislocation group dynamics, hydrogen diffusion, and vacancy diffusion. Furthermore, these concepts were also applied for estimating the degree of viscoelastic deterioration of blood vessel walls, which is dominated by a time-dependent mechanism, and for the diagnosis of aneurysm accompanied by the viscoelastic deterioration of the blood vessel wall. In these theories, new mechanical indexes were derived as dominant factors for predicting the life of fatigue crack growth and the time-dependent fracture of notched specimens of materials such as hydrogen embrittlement and high-temperature creep. Furthermore, as an example of a practical application, these theories were applied to estimate the degree of viscoelastic deterioration and chaotic motions of blood vessel walls, which are closely related to blood vessel diseases such as atherosclerosis and aneurysm. Moreover, new indexes to diagnose them were also proposed for clinical applications.

Transcranial direct current stimulation combined with bodyweight support–tai chi footwork for motor function of stroke survivors: a study protocol of randomised controlled trial

“…35 The refined test of balance ability will include (1) limit of stability (LOS): the LOS test is a sensitive and reliable measure for dynamic balance control, which refers to the farthest distance in eight different directions without taking any steps during trunk movement within the support base. Quantify the results by calculating the ratio of the linear distance from the centre of gravity to the target point to the actual path length; the score is higher, the better dynamic balance control; 36 (2) modified Clinical Test of Sensory Integration of Balance (m-CTSIB): the m-CTSIB is an effective and clinically significant sensory tissue measurement method 37 which provides a general evaluation of the participant's capability for sensory integration of balance (ie, visual, vestibular, proprioception) during (eg, step length, step velocity and single support time), the ROM and net muscle moment of the lower limb joints in the flexion-extension directional during the self-selected speed walking will be assessed. Full-body three-dimensional kinematics and ground reaction forces were collected by a 10-camera infrared motion capture system (Vicon Motion Systems, Oxford, UK) and the force platform (Kistler Instruments AG Corp., Switzerland), respectively.…”