Because solder joint interconnections are the weaknesses of microelectronic packaging, their reliability has great influence on the reliability of the entire packaging structure. Based on an accelerated life test the reliability assessment and life prediction of lead-free solder joints using Weibull distribution are investigated. The type-I interval censored lifetime data were collected from a thermal cycling test, which was implemented on microelectronic packaging with lead-free ball grid array (BGA) and fine-pitch ball grid array (FBGA) interconnection structures. The number of cycles to failure of lead-free solder joints is predicted by using a modified Engelmaier fatigue life model and a type-I censored data processing method. Then, the Pan model is employed to calculate the acceleration factor of this test. A comparison of life predictions between the proposed method and the ones calculated directly by Matlab and Minitab is conducted to demonstrate the practicability and effectiveness of the proposed method. At last, failure analysis and microstructure evolution of lead-free solders are carried out to provide useful guidance for the regular maintenance, replacement of substructure, and subsequent processing of electronic products.

/pdf/thermal-cycling-life-prediction-of-sn-3-0ag-0-5cu-solder-vbnq7qkltb.pdf

Thermal Cycling Life Prediction of Sn-3.0Ag-0.5Cu Solder Joint Using Type-I Censored Data

For advanced attitude control of the satellite, reaction wheels are used, which are actuated by motor. Fault detection and prediction of Remaining Useful Life (RUL) of the motor is of great importance. This study aims to demonstrate health management of reaction wheel motor in satellites by estimating the RUL of the damping coefficient. Multi-scale Extended Kalman Filter (EKF) is employed for this purpose using the data of input current and output velocity measured during the life test of the motor. The motor dynamic behavior is modeled by the ordinary differential equations. The damping coefficient is taken as the health indicator, which is obtained by solving the micro EKF problem. To set threshold for the damping coefficient, degradation behavior of characteristic curve that evaluates the motor performance is used to correlate with the degradation of the damping coefficient. Then, the RUL is predicted by solving the macro EKF problem.

/pdf/remaining-useful-life-prediction-of-reaction-wheel-motor-in-nc0dt1n9z4.pdf

Remaining useful life prediction of reaction wheel motor in satellites

Electric motors, converting electrical energy into mechanical energy, are widely utilized as the primary power source for electromechanical equipment. However, the huge energy consumption of electric motors makes their energy efficiency improvements crucial for achieving greenhouse gas reduction goals. As a result, low-efficiency asynchronous motors are being eliminated, while their high-value recycling has subsequently become a key issue. Remanufacturing offers a promising solution to upgrade low-energy efficiency asynchronous motors to high-energy efficiency permanent magnet synchronous motors, but its environmental benefits are unclear. A novel dynamic assessment model that integrates life cycle assessment and lifetime distribution modeling to evaluate the environmental benefits of motor remanufacturing is established. A manufacturing and four remanufacturing scenarios based on the damage profile of individual motor components are developed. The results demonstrate that motor remanufacturing can significantly reduce carbon emissions by 26.75%–65.13%. The model was also applied to various recycling scenarios and synchronous motor market penetration levels to provide a long-term environmental benefit in the motor industry in China by 2040. Findings suggest that the motor remanufacturing industry can achieve peak carbon reduction in 2035 and 2033 under the medium and high market penetration scenarios, respectively. It's also disclosed that remanufacturing offers considerable material savings (36%–73%), energy savings (28%–63%), and water savings (34%–88%). The environmental benefits of motor remanufacturing industry are quantified for the first time, demonstrating its effectiveness in facilitating a green and low-carbon transition. The dynamic assessment methodology system constructed in this research can provide a theoretical framework and research ideas for the environmental impact assessment of other end-of-life product management. 

Dynamic simulation of life cycle environmental benefits of remanufacturing asynchronous motors to permanent magnet synchronous motors

Because the traditional maintenance method of seawalls suffers from problems of insufficient maintenance support ability and significant waste of resources, there is an urgent need to establish a scientific management system for seawalls. Therefore, advanced prognostics and health management (PHM) technology was introduced into seawalls, structure of the seawall PHM system was set up, and the health assessment model and the maintenance decision model of the seawall PHM system were studied. Combining the characteristics of seawalls and high-frequency monitoring information, the seawall health assessment indexes were selected and the weights of health assessment indexes were calculated by projection pursuit model. Then, the health assessment model was set up using fuzzy comprehensive assessment method. The Weibull proportional hazard model was used to link the health state, running time, and failure rate of the seawall. Using maximum availability as the decision objective, the maintenance decision model was established base on the Weibull proportional hazard model. The example analysis shows that the health assessment model can assess seawall health effectively and the maintenance decision model can make correct maintenance decisions in a timely fashion based on the seawall health state.

Health Assessment Model and Maintenance Decision Model for Seawall Prognostics and Health Management System

http://koreascience.or.kr:80/article/JAKO201625059045622.pdf

A Comparison of the Reliability Estimation Accuracy between Bayesian Methods and Classical Methods Based on Weibull Distribution

Based on random censored data, the maximum likelihood estimation method of parameters of the weibull distribution is put forward. By the parameters estimation, the reliability analysis of the engineering data of rocket engine trials is given. The estimation values of shape parameters and reliability analysis show that the method is feasible.

Maximum likelihood estimation of weibull distribution based on random censored data and its application

Induction motors are widely used in industry, and usually have a long life. To predict the life and reliability of the motors within a reasonable time, a simple and available accelerated degradation testing method is presented. To simulate the unbalanced load on the motor, the lamina with circular holes is mounted on the shaft of the motor eccentrically, and different unbalanced loads are obtained by changing the mounted places of the lamina. A motor accelerated test with three kinds of stress is applied, and the Orbit Areas are used to reveal the performance degradation index of motor. The life and reliability of the motor is finally predicted and evaluated with a balanced lamina mounted on the shaft as its normal working condition. The accelerated degradation testing approach has been proven to be practical to predict the life of the motors.

Study on the life prediction of induction motors based on accelerated degradation testing method

The invention relates to a dynamic stress accelerated life test profile compilation method. The method comprises the following steps that 1, on the basis of a damage equivalent principle, dynamic stress is converted into static stress within a certain time interval; 2, on the basis of the step 1, an equivalent relation of a dynamic stress accelerated factor and a static stress accelerated factor is obtained; 3, the dynamic temperature stress is adopted as the dynamic stress, and on the basis of an Arrhenius model, dynamic temperature accelerated stress accelerated factor computational formulais obtained; 4, the dynamic temperature accelerated stress profile is compiled, and three parameters including a dynamic temperature accelerated stress mean value Tm*, a dynamic temperature accelerated stress amplitude Ta* and a dynamic temperature accelerated stress cycle period w* are determined. According to the method, the dynamic stress accelerated life test profile can be designed accordingto the dynamic change environment actually adopted by products, the reality degree simulated by the environment conditions in the accelerated test is improved, and it is ensured that the product failure mechanism in the test is consistent to that under the actual service condition.

Dynamic stress accelerated life test profile compilation method

For complex system with Long-term storage, only a few storage information can be obtained, usually including the data of periodical curtailed inspection and some routine test data. It is very difficult to assess the storage life and reliability of complex system under this condition. In order to resolve the practical engineering problem, a storage information acquisition method is proposed by combining accelerated storage test with qualification test on ground. By this method the typical single machine and simple system storage information were acquired. All kinds of typical equipment storage information and nonmetal material, which include accelerated storage test information, qualification test information on ground, on-site storage information, storage environment data and routine test information, are fused into the new storage information database. On the foundation, storage life and reliability assessment method for complex system is developed based on the field storage information and accelerated test information fusion analysis. And then, the storage reliability of the stored complex system storing for several years is given by that assessment method.

Study on storage reliability assessment method of complex system based on life distribution

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Haibo Li

Author Tools

Chat about Author

Papers

Maximum likelihood estimation of weibull distribution based on random censored data and its application

Study on the life prediction of induction motors based on accelerated degradation testing method

Dynamic stress accelerated life test profile compilation method

Study on storage reliability assessment method of complex system based on life distribution