Understanding the defect characterization of electronic and mechanical components is a crucial step in diagnosing component lifetime. Technologies for determining reliability, such as thermal modeling, cohesion modeling, statistical distribution, and entropy generation analysis, have been developed widely. Defect analysis based on the irreversibility entropy generation methodology is favorable for electronic and mechanical components because the second law of thermodynamics plays a unique role in the analysis of various damage assessment problems encountered in the engineering field. In recent years, numerical and theoretical studies involving entropy generation methodologies have been carried out to predict and diagnose the lifetime of electronic and mechanical components. This work aimed to review previous defect analysis studies that used entropy generation methodologies for electronic and mechanical components. The methodologies are classified into two categories, namely, damage analysis for electronic devices and defect diagnosis for mechanical components. Entropy generation formulations are also divided into two detailed derivations and are summarized and discussed by combining their applications. This work is expected to clarify the relationship among entropy generation methodologies, and benefit the research and development of reliable engineering components.@en

With the rapid development of lighting technology and auto industry, it has been an important research subject for many motor manufacturers to improve headlight performance. LED light has achieved a dominant position in lighting technology because of the advantages, such as the small size, low energy consumption, and long service life. In a complex working environment, the reliability of light source module is an indispensable parameter for a LED headlight, which can lead to poor energy efficiency, decreased light intensity, and a shorter service life with low reliability. In the working process of headlights, the rising LED temperature will reduce the luminous flux and thermostability, even affect normal operation. Therefore, understanding and evaluating the relevant factors affecting LED reliability is an important measure to ensure the stabilizations of LED headlights. In this paper, the finite element software and optical simulation software are used to simulate the temperature field, flow field, and optics of the LED headlight module. Firstly, in order to understand the influence of temperature on the stability of the headlight, the temperature field and flow field distribution of the headlight are studied by finite element software. Secondly, we use the optical simulation software to study the optical parameters of headlight at different temperatures. It shows that the highest temperature appears in the LED chip, and the lowest temperature appears in the maximum end face of the headlight shell. For the same power LED, the higher working temperature leads to higher LED junction temperature. Affected by the working environment temperature, the luminous flux of the headlight will decrease with the increase of temperature.@en