The subsurface stress plays an important role in the damage of the movable contact element, but most subsurface stresses are obtained with numerical calculations according to the contact mechanics. In the present paper, a new method to measure the subsurface stress of the movable element is proposed with using photoelastic technology. Although the technology has been widely used in measuring the stress of the static elements, it is seldom used in the moving body because the observed point is moving. After the experimental tester is introduced in detail, the principles of the photoelastic technology are presented. The tester is designed to be able to working in the three conditions, the static, the rolling and the sliding in the line or surface contacts. The experimental results, that is the interference fringes, of the three states are then presented in the different loads and the rotational speeds. Because the fringe figures indicate the maximum shear stress distribution in the body of the moving element, we can find what the real stress distribution in the rolling or sliding element is alike.

The subsurface stress plays an important role in the damage of the movable contact element, but most subsurface stresses are obtained with numerical calculations according to the contact mechanics. In the present paper, a new method to measure the subsurface stress of the movable element is proposed with using photoelastic technology. Although the technology has been widely used in measuring the stress of the static elements, it is seldom used in the moving body because the observed point is moving. After the experimental tester is introduced in detail, the principles of the photoelastic technology are presented. The tester is designed to be able to working in the three conditions, the static, the rolling and the sliding in the line or surface contacts. The experimental results, that is the interference fringes, of the three states are then presented in the different loads and the rotational speeds. Because the fringe figures indicate the maximum shear stress distribution in the body of the moving element, we can find what the real stress distribution in the rolling or sliding element is alike.

Introduction: Heart failure (HF) is a common chronic disease with high morbidity and mortality rates. Besides HF treatments aimed to improve patients’ quality of life and health status, health education interventions for behavioral changes ensuring their adherence to treatment are very important. Therefore, this study aimed to evaluate the effect of behavioral health education interventions on knowledge, treatment adherence, and quality of life of patients with HF. Methods: This was a randomized controlled trial. A total of 330 patients were selected and randomly distributed into intervention and control groups (n = 165 per group). Data were collected at the time points before the intervention and three months after the intervention using the Dutch Heart Failure Knowledge Scale (DHFKS), Revised Heart Failure Compliance Scale (RHFCS), and quality of life (EQ-5D-5L v2.1, Vietnamese version). Results: There were no significant differences between the two groups in HF knowledge or quality of life at baseline. After three months of health education intervention, intervention group significant increase to 1.68 times (95%CI: 1.05 – 2.69; p=0.03) in overall HF knowledge; 1.91 times (95%CI: 1.25 – 2.92; p=0.003) in general HF knowledge and 1.59 times (95%CI: 1.03 – 2.45; p=0.038) in behavior of exercise when compare to control group. However, the quality of life did not change significantly after the intervention. Conclusions: Although the health education intervention had no impact on the quality of life of patients with HF, it was effective in improving their HF knowledge and treatment adherence.

Contact problems have been widely investigated for many years. However, there are few reports on the real-time observation of shear stress evolution in friction process by experimental method. In this paper, the plane stress fields of slider-on-block contact in different contact states were observed by photoelasticity experiments and finite element simulation. In the static state, the slider is only subjected to a normal force by an L-shaped body above the slider while the block is fixed. However, in the slip state, the block is moved, and the slider is acted upon by normal and tangential forces. In both cases, the principal stress difference fields in the block obtained by photoelasticity and simulation were basically consistent. Additionally, based on simulation, the distributions of pressure and frictional stress on the contact surface were determined; the influences of the load and friction coefficient on the contact stress distributions were also investigated. Accordingly, some principles for contact stress distribution were obtained. The combination of experimental and simulation methods aims to be complementary, helping to better understand the nature of the contact stress field.