Michael Pecht

Michael Pecht
University of Maryland, College Park | UMD, UMCP, University of Maryland College Park · Center for Advanced Life Cycle Engineering (CALCE)

Ph.D.

About

1,479
Publications
608,782
Reads
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35,462
Citations
Citations since 2017
409 Research Items
21451 Citations
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Introduction
Prof Michael Pecht the director of CALCE, which is supported at over $6M by over 150 worldwide companies. There are 12 working teams in CALCE. Prof Pecht's team is working on various reliability and safety issues associated with electronic components, batteries, and products. His team includes his 30 Ph.D. students, 15 visiting scholars, and 6 research scientists. CALCE has one of the world's largest electronics testing and failure analysis facilities.

Publications

Publications (1,479)
Article
State of health (SOH) prediction is key to battery health management and safety. Health indicators (HIs) are effective and feasible to predict battery SOH. The existing approaches according to HIs focused on single-source features of HIs such as voltage, current or temperature by a single model to predict SOH. The accuracy and robustness of these a...
Article
Recycling lithium-ion batteries (LIBs) has gained prominence in the last decade due to increasing supply chain constraints for critical materials (such as lithium and cobalt) and policy shift toward increased circularity of materials to mitigate environmental concerns. Conventional recycling methods (e.g., pyrometallurgical techniques) are suboptim...
Article
The dependent competing failure process model has received increasing research attention in recent years due to its essential role in describing system reliability. For the δ shock model, as a main type of shock in dependent competing failure process, the system fails if the interval of time between two sequential shocks is less than a threshold δ....
Article
The capacity of lithium-ion batteries decreases during usage (cycling) and storage (rest). After some initial charge-discharge cycling, the capacity fade rate has been observed to increase, and the capacity fade curve visibly bends, the onset of which is described as a knee point. The occurrence of the knee point above the end-of-life capacity thre...
Article
Full-text available
The Jiles–Atherton model is widespread in the hysteresis description of ferromagnetic, ferroelectric, magneto strictive, and piezoelectric materials. However, the determination of model parameters is not straightforward because the model involves numerical integration and the solving of ordinary differential equations, both of which are error prone...
Article
Full-text available
As fixed-wing unmanned aerial vehicles (FW-UAVs) are used for diverse civil and scientific missions, failure incidents are on the rise. Recent rapid developments in deep learning (DL) techniques offer advanced solutions for fault diagnosis of UAVs. However, most existing DL-based diagnostic models only perform well when trained on massive amounts o...
Article
Rotating machinery fault diagnosis based on deep learning has been successfully applied in modern industrial equipment. However, many existing types of research suffer from two significant deficiencies. First, most deep neural networks are based on a single or same kind of similarity measurement method, which cannot fully exploit the data to extrac...
Article
Full-text available
Image monitoring of oil wear particles is currently only applicable to microflows and is susceptible to bubble interference. This paper develops an optical oil-monitoring system that can be used for large-diameter pipes with high flow rates. A shallow and wide observation cell with an equivalent diameter of Φ5 mm is designed to allow a theoretical...
Article
The large-scale retirement of electric vehicle traction batteries poses a huge challenge to environmental protection and resource recovery since the batteries are usually replaced well before their end of life. Direct disposal or material recycling of retired batteries does not achieve their maximum economic value. Thus, the second-life use of EV b...
Article
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This paper presents the various ways that lithium-ion batteries are being counterfeited, the problems that counterfeit batteries present, how they enter the consumer market, and the difficulties of detection. Simple external visual inspection of the battery is unreliable. As shown in the presented case study, even for the same brand batteries, thei...
Article
Full-text available
The continuous occurrence of lithium-ion battery system fires in recent years has made battery system fault diagnosis a current research hotspot. For a series connected battery pack, the current of each cell is the same. Although there are differences in parameters such as internal ohmic resistance, the relative change of parameters between cells i...
Article
Lithium-ion battery diagnostics and prognostics rely on measurements of electrical impedance, capacity, and voltage to infer the internal state of the battery. Mechanical changes to the cell structure represent an additional measure of the battery’s state because these changes are related to the overall battery health. As lithium-ion batteries are...
Article
Full-text available
Lithium-ion batteries must undergo a series of quality control tests before being approved for sale. In this study, quality control tests were carried out on two types of lithium-ion pouch batteries, here denoted as type A (with stacked electrode configuration) and type B (with a jelly-roll arrangement) to assess the effectiveness of the tests. Ele...
Article
Accurately predicting batteries’ ageing trajectory and remaining useful life is not only required to ensure safe and reliable operation of electric vehicles (EVs) but is also the fundamental step towards health-conscious use and residual value assessment of the battery. The non-linearity, wide range of operating conditions, and cell to cell variati...
Article
This article presents a comparison between the performances of two chemistries of synthetic oil lubricants, polyalphaolefins (PAOs), and perfluoropolyethers (PFPEs) when applied on gold-plated electrical contacts operating at contact loads of 9.8 centiNewton (cN) and experiencing fretting-induced degradation. Performance assessment was done using t...
Article
This paper proposes a novel nondestructive diagnostic method for flip chips based on an improved semi-supervised deep extreme learning machine (ISDELM) and vibration signals. First, an ultrasonic transducer is used to generate and focus ultrasounds on the surface of the flip chip to excite it, and a laser scanning vibrometer is applied to acquire t...
Article
Full-text available
Analog circuits are a critical part of industrial electronics and systems. Estimates in the literature show that, even though analog circuits comprise less than 20% of all circuits, they are responsible for more than 80% of faults. Hence, analog circuit fault diagnosis and isolation can be a valuable means of ensuring the reliability of circuits. T...
Article
Bearing fault diagnosis suffers from class imbalances and distributional discrepancies of fault data under different working conditions. The class imbalance of the fault class increases the difficulty of learning the classification boundary of the diagnostic model for the minority class. Furthermore, the diversities of feature distributions decreas...
Article
Full-text available
Lithium-ion (Li-ion) batteries have increasingly been used in diverse applications. Accurate estimation of the state of health (SOH) of the Li-ion batteries is vital for all stakeholders and critical in various applications such as electric vehicles (EVs). The electrical equivalent circuit (EEC) 2-RC model is often used to model the battery operati...
Article
Full-text available
Lithium-ion batteries are the ubiquitous energy storage device of choice in portable electronics and more recently, in electric vehicles. However, there are numerous lithium-ion battery chemistries and in particular, several cathode materials that have been commercialized over the last two decades, each with their own unique features and characteri...
Article
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The Prognostics and Health Management (PHM) of electronic systems has reached high levels of maturity, with both generic and system-specific PHM techniques available. While these techniques are able to detect naturally occurring faults and predict their impact on the system lifetime, they might not be able to do so if the faults are maliciously ind...
Article
Water in its various forms can affect the performance and reliability of today’s electronics in unique ways. This paper discusses the forms of water and the degradation effect of water on electronics, identifies the types of failure mechanisms in electronics induced by liquid and vapor phase water, presents case studies of water-related failures, a...
Article
In practical mechanical fault detection and diagnosis, it is difficult and expensive to collect enough large-scale supervised data to train deep networks. Transfer learning can reuse the knowledge obtained from the source task to improve the performance of the target task, which performs well on small data and reduces the demand for high computatio...
Article
An electrochemical model can accurately describe both internal and external characteristics of lithium-ion batteries. However, when the model is adopted for a battery pack, the inconsistency of the cells in a pack increases the difficulty of battery modeling and parameter identification. This work develops an electrochemical model parameter identif...
Article
Internal resistance offers accurate early-stage health prediction for Li-Ion batteries. • Prediction accuracy is over 95% within the first 100 cycles at room temperature. • Demonstrated that internal resistance dynamics characterize battery homogeneity. • Homogeneous batteries can share the same early-stage prediction models. • Internal resistance...
Article
Li-ion batteries are commercially successful power sources for diverse applications. However, the characteristics of Li-ion batteries make them susceptible to thermal runaway, resulting in fires and explosions. To mitigate safety hazards prior to the occurrence of thermal runaway, various strategies have been applied for battery cells, as well as b...
Article
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Unpowered exoskeletons (UEs) have attracted extensive research attentions for their portability, handleability and simplicity. However, designing exoskeletons without any active actuators is a great challenge because essential criteria such as performance enhancement, low impedance, and comfort must be met. This paper reviews the UEs researches fro...
Article
Full-text available
The state of health (SOH) reflects the health status of the lithium-ion battery and is expected to accurately predicted, so as the corresponding maintenance measures can be taken to ensure the safe operation of the battery. This paper proposed a SOH prediction method based on multi-kernel relevance vector machine (RVM) and whale optimization algori...
Article
The demand for safer and cost-effective lithium-ion batteries with higher energy density and longer life requires thorough investigation into the structural and electrochemical behavior of cell components. Binders are a key component in an electrochemical cell that function to interconnect the active material and conductive additive and adhere firm...
Article
Full-text available
Lithium-ion battery datasheets, also known as specification sheets, are documents that battery manufacturers provide to define the battery’s function, operational limit, performance, reliability, safety, cautions, prohibitions, and warranty. Product manufacturers and customers rely on the datasheets for battery selection and battery management. How...
Article
Full-text available
In this paper, a system reliability model subject to Dependent Competing Failure Processes (DCFP) with phase-type (PH) distribution considering changing degradation rate is proposed. When the sum of continuous degradation and sudden degradation exceeds the soft failure threshold, soft failure occurs. The interarrival time between two successive sho...
Article
Full-text available
Many mechanical systems are subject to degradation and random shock processes, which are dependent and competing. The two processes are soft failure process and hard failure process, either of which occurs will cause the system to fail. In this paper, a hard failure model of the gear system is established based on the Stress‐Strength Interference m...
Article
Due to the rapid expansion of electric vehicles and portable electronics, the demand for lithium-ion batteries is increasing, resulting in supply risks in obtaining lithium, cobalt, and other materials, as well as issues associated with spent battery disposal. The current battery recycling processes vary by specific battery chemistries and impact b...
Article
In battery-powered electronic devices, an increase in the discharge C-rate is expected when using functions that require more power. Temperature rise is the thermal effect of discharge C-rate due to ohmic heating, causing lithium-ion batteries to degrade faster. There are also non-thermal effects, such as increased mechanical stress on electrode pa...
Article
Full-text available
Insulated gate bipolar transistor (IGBT) is widely used in power equipment, it generally works in complex circuit profiles and it is very difficult to measure or predict the thermal parameters of the module in real-time and evaluate the corresponding health status in the transient process. This paper develops a novel approach for solder-layer condi...
Article
Full-text available
Electric vehicles (EV) are considered the future of the automobile industry due to their high energy conversion efficiency and environmental friendliness. However, there are safety risks associated with Li-ion batteries, including the potential for fires and explosions. This paper reviews the challenges facing the electric vehicle market regarding...
Article
A half-cell test is often used to obtain electrode potentials for lithium-ion batteries when using an electrochemical model to simulate terminal voltage, which needs a series of time-consuming processes. However, this method generally requires expensive electrochemical measuring equipment, reference electrodes, and a vacuum glove box. This study de...
Article
Full-text available
As a simple and unsupervised feature learning method, sparse filtering has shown potential in rotating machinery fault diagnosis. However, sparse filtering has the following deficiencies: (a) the optimal sparsity of the learned features cannot be determined. (b) As a shallow network, sparse filtering has a limited capability of learning discriminat...
Article
Deep neural networks (DNNs) have shown potential in intelligent fault diagnosis of rotating machinery. However, traditional DNNs such as the back-propagation neural network are highly sensitive to the initial weights and easily fall into the local optimum, which restricts the feature learning capability and diagnostic performance. To overcome the a...
Article
Automatic inspection methods based on machine vision have been widely employed for steel surface defect detection. The central purpose of these methods is to extract features to represent different defects. However, current methods depend on machine learning that demands handcrafted features and overlooks the domain shift. In this paper, we propose...
Article
Full-text available
Lithium-ion batteries are ubiquitous in applications ranging from portable electronics to electric vehicles. Irrespective of the application, reliable real-time estimation of battery state of health (SOH) by on-board computers is crucial to the safe operation of the battery, ultimately safeguarding asset integrity. In this Article, we design and ev...
Book
Nature-Inspired Computing Paradigms in Systems: Reliability, Availability, Maintainability, Safety and Cost (RAMS+C) and Prognostics and Health Management (PHM) covers several areas that include bioinspired techniques and optimization approaches for system dependability. The book addresses the issue of integration and interaction of the bioinspire...
Article
This paper develops a hybrid remaining useful life (RUL) prediction method and explores the feasibility for complex system equipment, using one of transmission equipment D-cables in high-speed railways as an example. RUL prediction is a promising way to reduce high maintenance costs for high-speed railways. However, there is no sufficient actual li...
Article
Lithium-ion battery systems have dynamic diffusivity properties that continuously change as a function of state of charge due to lithium concentration gradients and material phase changes in both electrodes. Additionally, external factors such as pressure and temperature can further influence the ion-diffusion-rate profile with respect to the open-...
Preprint
Full-text available
This paper presents a comparison between the performances of two chemistries of synthetic oil lubricants, polyalphaolefins (PAOs) and perfluoropolyethers (PFPEs) when applied on gold-plated electrical contacts operating at contact loads of 9.8 cN and experiencing fretting-induced degradation. Performance assessment was done using the contact resist...
Article
Full-text available
This paper develops generalized sparse filtering (GSF) by applying general norm normalization to improve the feature learning ability. A rotating machinery fault diagnosis method is then developed by combining the GSF and softmax regression. A rolling bearing dataset is applied to validate the performance of the developed method. The influences of...
Article
Full-text available
In this paper, a novel multistage reliability model is provided as systems are often divided into many stages according to system degradation characteristics. Multistage hard failure (caused by random shock) process (MHFP) and multistage soft failure (caused by random shock and continuous degradation) process (MSFP) are introduced to describe the c...
Article
Failure of hot components in gas turbines often causes catastrophic results. Early fault detection can prevent serious incidents and improve the availability. A novel early fault detection method of hot components is proposed in this article. Exhaust gas temperature is usually used as the indicator to detect the fault in the hot components, which i...
Article
The demand for stretchable strain sensors has increased exponentially due to their ideal interaction with the human body. However, developing stretchable strain sensors with balanced properties such as a low Young’s modulus, easy fabrication, low cost, large deformation, and fast response time remains a challenge. In this study, we simultaneously p...
Article
Full-text available
Many systems are usually subjected to the combined effects of degradation and random shocks at the same time. Their failures are the competitive result of soft failure caused by degradation and hard failure caused by shocks. For operating machinery, wear failure is the main failure mechanism, and the machine is also subject to shock during the wear...
Article
Full-text available
Electrochemical capacitors (ECs) have only recently been considered as an alternative power source for telemetry sensors of drilling equipment for geothermal or oil and gas exploration. The lifecycle analysis and modelling of ECs is underrepresented in literature in comparison to other storage devices e.g. Li-ion batteries. This paper investigates...
Article
Lithium-ion batteries are considered fully charged when they are charged to the battery manufacturer's specified cut-off voltage using the specified cut-off C-rate. To assess the consequences of going beyond this charged state, four types of 18650 lithium-ion battery cells were charged from 100% state of charge until the cells' internal safety mech...
Preprint
Full-text available
Lithium-ion batteries are ubiquitous in modern day applications ranging from portable electronics to electric vehicles. Irrespective of the application, reliable real-time estimation of battery state of health (SOH) by on-board computers is crucial to the safe operation of the battery, ultimately safeguarding asset integrity. In this paper, we desi...
Article
Full-text available
Lithium-ion batteries power numerous systems from consumer electronics to electric vehicles, and thus undergo qualification testing for degradation assessment prior to deployment. Qualification testing involves repeated charge–discharge operation of the batteries, which can take more than three months if subjected to 500 cycles at a C-rate of 0.5C....
Article
The performance of lithium‑iron-phosphate batteries changes under different ambient temperature conditions and deteriorates markedly at lower temperatures (< 10 °C). This work models and simulates lithium‑iron-phosphate batteries under ambient temperatures ranging from 45 °C to −10 °C. Essential modifications based on an existing electrochemical mo...
Article
While solder interconnects tend to be the focus of reliability studies in electronics, increased exposure to flexural loads and the use of stiffer (higher density) packages are raising concern regarding the fatigue failure of copper metallization (traces and solder pads) on printed circuit boards. To better understand the failure risks of copper tr...
Article
Full-text available
The bathtub model has often been cited as a hazard rate profile that predicts not only human mortality but also the hazard rate of manufactured products. This paper examines the inapplicability of the bathtub model to predict the hazard rate of electronic components, products, and systems. The paper reviews various literature and uses numerous expe...
Article
Full-text available
Battery packs are applied in various areas (e.g., electric vehicles, energy storage, space, mining, etc.), which requires the state of health (SOH) to be accurately estimated. Inconsistency, also known as cell variation, is considered a significant evaluation index that greatly affects the degradation of battery pack. This paper proposes a novel jo...
Article
The moving average (MA)-type scheme, also known as the smoothing method, has been well established within the multivariate statistical process monitoring (MSPM) framework since the 1990s. However, its theoretical basis is still limited to smoothing independent data, and the optimality of its equally or exponentially weighted scheme remains unproven...
Article
Full-text available
Ram Adapa (Fellow, IEEE) received the B.S. degree from Jawaharlal Nehru Technological University, India, the M.S. degree from IIT Kanpur, India, and the Ph.D. degree from the University of Waterloo, ON, Canada, all in electrical engineering.
Article
Full-text available
18650 Lithium-ion batteries are wildly used as power sources for portable electronics because of the standardized format and economical manufacturing cost. However, commercial 18650 cells come in various designs due to the implementation of different protection devices. The current interrupt device and top vent are mandatory protection devices for...
Conference Paper
The article describes the construction of optimizing Self-maintenance solutions based on PHM systems, represented as neurosingular machines. The main attention is focused on the description of singular processes in incoming data flows: topological singularities, strong asingularities, singular probability measures. On the basis of topological analy...
Article
Full-text available
Smartphones account for a large and growing portion of global electronic waste, and the life extension of electronic systems—particularly by refurbishment—is a viable solution for reducing this waste stream. In some secondary markets, sales of refurbished smartphones have begun to outpace sales of new smartphones. However, there are concerns over t...
Chapter
Testing is conducted to verify that the connectors will properly perform over time (reliability) per the application requirements. In general, electrical tests for connectors include dielectric withstanding voltage, low‐signal‐level contact resistance, insulation resistance, contact resistance, and standing wave ratio. Environmental tests include h...
Chapter
Connectors are an essential part of electronic systems. This chapter discusses various fretting mechanisms in detail. Fretting is micromotions between contacting surfaces. J. Swingler divided contact failure into four broad types: chemical, mechanical, physical, and a combination of these failures. Chemical factors such as oxidation layer formation...
Chapter
Contact materials are usually made of metal alloys, predominantly copper alloys. The contact materials are evaluated in terms of their electrical conductivity, mechanical strength, resistance to stress relaxation or creep, solderability, and resistance to corrosion. Nickel alloys also show considerably higher mechanical strength than copper alloys,...
Chapter
A connector housing provides mechanical support for the contact members, electrically insulates contact members, and helps exert and maintain a contact pressure to ensure proper electrical connection. The properties of connector housing materials include heat deflection temperature, glass transition temperature, mechanical strength, flammability, d...
Chapter
Contact plating (finish) provides corrosion protection for base metals and optimizes the mechanical and electrical properties of the contact interfaces. Contact plating can provide a shield from environmental attacks to the copper alloy base metals, thus prohibiting the accumulation of an insulating layer on the contact interface and maintaining it...
Chapter
Advanced technology attachment (ATA), the standardized version of integrated drive electronics (IDE), and serial ATA (SATA) are the mass storage device interfaces that connect hard disk drives (HDDs), optical disks, and solid‐state drives (SSDs) to a computer motherboard. This chapter covers the ATA as well as the newer and faster SATA connectors....
Chapter
Various connectors by numerous manufacturers are available in the market. Some of the key manufacturers include Amphenol, Aptiv, Fischer Connector, Hirose, Molex, and TE Connectivity. This chapter presents some of their products and focuses on the specifications, types, limitations, advantages, and usage in a particular application. The products ar...
Chapter
The performance of signal connectors is addressed in two broad topics: signal transmission quality and electromagnetic compatibility. Creating a connector starts with a layout design based on electrical and mechanical requirements. This design is then analyzed iteratively to ensure that it meets the required electrical and mechanical standards and...
Chapter
The interface between the connector and the connecting components (board or wire) is referred to as the “back‐end” connection. The type of back‐end connection depends on whether the connector is connected to a board or a wire. Soldering is the most widely used connection methodology. An insulation displacement connection (IDC) or crimping connectio...