Shock and Dynamic Loading in Portable Electronic Assemblies: Experimental Results

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
A. F. Askari Farahani ◽  
M. Al-Bassyiouni ◽  
A. Dasgupta
Keyword(s):  
Dynamic Response ◽  
Dynamic Loading ◽  
Transient Response ◽  
Failure Modes ◽  
Dynamic Contact ◽  
System Level ◽  
Printed Wiring Board ◽  
Electronic Product ◽  
Electronic Assemblies ◽  
Plastic Housing

The development of portable electronics poses design challenges when evolving new designs for high strain-rate life cycle loading, such as in drop events, blast events, vibration, ultrasonic process steps, etc. This paper discusses an experimental investigation of the transient response of a portable electronic product and its subassemblies to dynamic mechanical loading encountered in drop and shock conditions. The portable electronic product tested in this study consists of a circuit card assembly and a battery pack supported in a two-piece plastic housing with a separate battery compartment. Dynamic loading, consisting of various shock profiles, is applied using an electrodynamic shaker. A number of drop tests are also conducted on a drop tower. Fourier transform technique (FFT) is utilized to analyze the dynamic response of the printed wiring board and the plastic housing in the frequency domain. Tests at the subassembly level are used to study the dynamic response of the individual constituents. The nonlinear interactions due to dynamic contact between these subassemblies are then investigated through shock and drop testing at the system level. These results will be used in a subsequent study to investigate the ability of finite element models to accurately capture this transient response of complex portable electronic assemblies under shock and drop loading. The long-term goal of this combined study is to demonstrate a systematic modeling methodology to predict the drop response of future portable electronic products, so that relevant failure modes can be eliminated by design iterations early in the design cycle.

scholarly journals Modeling and Simulation of Shock and Drop Loading for Complex Portable Electronic Systems

2009 ◽  
Author(s):  
F. Askari Farahani ◽  
M. Al-Bassyiouni ◽  
A. Dasgupta ◽  
S. Tolchinsky ◽  
J. Crystal
Keyword(s):  
Dynamic Response ◽  
Failure Modes ◽  
Electronic Systems ◽  
Computational Capability ◽  
Drop Tests ◽  
Shock Profiles ◽  
Electrodynamic Shaker ◽  
Electronic Assemblies ◽  
Plastic Housing

The dynamic response of electronic assemblies to drop and shock conditions is investigated through tests and simulation. The portable electronic product tested in this study consists of a circuit card assembly and a battery pack supported in a two-piece plastic housing with a separate battery compartment. Dynamic loading, consisting of various shock profiles, is applied using an electrodynamic shaker. A number of drop tests are also conducted on a drop tower. Fourier Transform technique (FFT) is utilized to analyze the dynamic response of the PWB and the plastic housing in the frequency domain. The loading events are modeled in ABAQUS™ [11]. Flexural strains and accelerations are compared to assess the agreement between the model results obtained here and the experimental results [10]. The long-term goal of this study is to demonstrate a systematic computational capability to predict the dynamic response and failure modes expected due to drop loading, during the design phase of future products.

Shock and Dynamic Loading in Portable Electronic Assemblies: Modeling and Simulation Results

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
A. F. Askari Farahani ◽  
M. Al-Bassyiouni ◽  
A. Dasgupta
Keyword(s):  
Finite Element ◽  
High Strain Rate ◽  
Strain Rate ◽  
Transient Response ◽  
Material Properties ◽  
Computational Models ◽  
Failure Modes ◽  
High Strain ◽  
Finite Element Models ◽  
Electronic Assemblies

In this study, the transient response of electronic assemblies to mechanical loading encountered in drop and shock conditions are investigated with transient finite element methods. Many manufacturers face design challenges when evolving new designs for high strain-rate life cycle loading. Examples of high strain-rate loading include drop events, blast events, vibration, ultrasonic process steps, etc. New design iterations invariably bring new unexpected failure modes under such loading and costly trial-and-error design fixes are often necessary after the product is built. Electronics designers have long sought to address these effects during the design phase, with the aid of computational models. However, such efforts have been difficult because of the nonlinearities inherent in complex assemblies and complex dynamic material properties. Our goal in this study is to investigate the ability of finite element models to accurately capture the transient response of a complex portable electronic product under shock and drop loading. Finite element models of the system are generated and calibrated with experimental results, first at the subsystem level to calibrate material properties and then at the product level to parametrically investigate the contact mechanics at the interfaces. The parametric study consists of sensitivity studies for different ways to model soft, nonconservative contact, as well as structural damping of the subassembly under assembly boundary conditions. The long-term goal of this study is to demonstrate a systematic modeling methodology to predict the drop response of future portable electronic products, so that relevant failure modes can be eliminated by design iterations early in the design cycle.

Case Studies of Brittle Interfacial Failures in Area Array Solder Interconnects

2000 ◽  
Author(s):  
George M. Wenger ◽  
Richard J. Coyle ◽  
Patrick P. Solan ◽  
John K. Dorey ◽  
Courtney V. Dodd ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Case Studies ◽  
Failure Modes ◽  
Electroless Nickel ◽  
Electrical Performance ◽  
Printed Wiring Board ◽  
Solder Interconnects ◽  
Area Array ◽  
Surface Finishes ◽  
Soldering Reaction

Abstract A common pad finish on area array (BGA or CSP) packages and printed wiring board (PWB) substrates is Ni/Au, using either electrolytic or electroless deposition processes. Although both Ni/Au processes provide flat, solderable surface finishes, there are an increasing number of applications of the electroless nickel/immersion gold (ENi/IAu) surface finish in response to requirements for increased density and electrical performance. This increasing usage continues despite mounting evidence that Ni/Au causes or contributes to catastrophic, brittle, interfacial solder joint fractures. These brittle, interfacial fractures occur early in service or can be generated under a variety of laboratory testing conditions including thermal cycling (premature failures), isothermal aging (high temperature storage), and mechanical testing. There are major initiatives by electronics industry consortia as well as research by individual companies to eliminate these fracture phenomena. Despite these efforts, interfacial fractures associated with Ni/Au surface finishes continue to be reported and specific failure mechanisms and root cause of these failures remains under investigation. Failure analysis techniques and methodologies are crucial to advancing the understanding of these phenomena. In this study, the scope of the fracture problem is illustrated using three failure analysis case studies of brittle interfacial fractures in area array solder interconnects. Two distinct failure modes are associated with Ni/Au surface finishes. In both modes, the fracture surfaces appear to be relatively flat with little evidence of plastic deformation. Detailed metallography, scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and an understanding of the metallurgy of the soldering reaction are required to avoid misinterpreting the failure modes.

Dynamic Behavior of a Hydraulically Actuated Mechanism. Part 2: Nonlinear Character

1986 ◽  
Vol 108 (2) ◽  
pp. 250-254
Author(s):  
V. Venkatraman ◽  
R. W. Mayne
Keyword(s):  
Dynamic Response ◽  
Transient Response ◽  
Adequate Description ◽  
Linear Behavior ◽  
Transmission Angle ◽  
Dimensionless Groups ◽  
Hydraulically Actuated ◽  
Nonlinear Character ◽  
The Common ◽  
Nonlinear Nature

The first of these papers considering a hydraulically actuated mechanism presents the common oscillating cylinder arrangement and sets of equations which describe the dynamic system. It then defines dimensionless groups that characterize the actuator-mechanism and explores the quasi-linear behavior of the system. This present paper focuses on the nonlinear nature of the system. Effects of transmission angle, mechanism geometry and loading are considered as well as the range of operation in which the small perturbation behavior provides an adequate description of the dynamic response. The paper closes by identifying a new parameter which plays an important role in characterizing the dependence of the system transient response on mechanism geometry.

Anomaly-Detection and Prognostication of Electronics Subjected to Shock and Vibration

2009 ◽  
Author(s):  
Pradeep Lall ◽  
Prashant Gupta ◽  
Arjun Angral ◽  
Jeff Suhling
Keyword(s):  
Experimental Data ◽  
Frequency Analysis ◽  
Health Monitoring ◽  
Solder Ball ◽  
Failure Modes ◽  
Feature Space ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Fault Mode ◽  
Electronic Assemblies

Failures in electronics subjected to shock and vibration are typically diagnosed using the built-in self test (BIST) or using continuity monitoring of daisy-chained packages. The BIST which is extensively used for diagnostics or identification of failure, is focused on reactive failure detection and provides limited insight into reliability and residual life. In this paper, a new technique has been developed for health monitoring and failure mode classification based on measured damage precursors. A feature extraction technique in the joint-time frequency domain has been developed along with pattern classifiers for fault diagnosis of electronics at product-level. The Karhunen Loe´ve transform (KLT) has been used for feature reduction and de-correlation of the feature vectors for fault mode classification in electronic assemblies. Euclidean, and Mahalanobis, and Bayesian distance classifiers based on joint-time frequency analysis, have been used for classification of the resulting feature space. Previously, the authors have developed damage pre-cursors based on time and spectral techniques for health monitoring of electronics without reliance on continuity data from daisy-chained packages. Statistical Pattern Recognition techniques based on wavelet packet energy decomposition [Lall 2006a] have been studied by authors for quantification of shock damage in electronic assemblies, and auto-regressive moving average, and time-frequency techniques have been investigated for system identification, condition monitoring, and fault detection and diagnosis in electronic systems [Lall 2008]. However, identification of specific failure modes was not possible. In this paper, various fault modes such as solder inter-connect failure, inter-connect missing, chip delamination chip cracking etc in various packaging architectures have been classified using clustering of feature vectors based on the KLT approach [Goumas 2002]. The KLT de-correlates the feature space and identifies dominant directions to describe the space, eliminating directions that encode little useful information about the features [Qian 1996, Schalkoff 1972, Theodoridis 1998, Tou 1974]. The clustered damage pre-cursors have been correlated with underlying damage. Several chip-scale packages have been studied, with leadfree second-level interconnects including SAC105, SAC305 alloys. Transient strain has been measured during the drop-event using digital image correlation and high-speed cameras operating at 100,000 fps. Continuity has been monitored simultaneously for failure identification. Fault-mode classification has been done using KLT and joint-time-frequency analysis of the experimental data. In addition, explicit finite element models have been developed and various kinds of failure modes have been simulated such as solder ball cracking, trace fracture, package falloff and solder ball failure. Models using cohesive elements present at the solder joint-copper pad interface at both the PCB and package side have also been created to study the traction-separation behavior of solder. Fault modes predicted by simulation based pre-cursors have been correlated with those from experimental data.

scholarly journals Dynamic response of Zelazny Most tailings dam to mining induced extreme seismic event occurred in 2016

2019 ◽  
Vol 262 ◽  
pp. 01001
Author(s):  
Aleksandra Korzec ◽  
Waldemar Świdziński
Keyword(s):  
Stability Analysis ◽  
Dynamic Response ◽  
Dynamic Loading ◽  
Time Integration ◽  
Horizontal Displacement ◽  
Material Model ◽  
Implicit Time ◽  
Tailings Dam ◽  
Peak Horizontal Acceleration ◽  
The Stability

The paper deals with the stability analysis of tailings dam subjected to dynamic loading induced by mining shocks which occurred in neighbouring copper mine. The main goal of the paper was to model the dynamic response of the dam during two extreme paraseismic events which occurred in 2016 based on accelerograms recorded at the dam toe. Dynamic response of the tailings dam was calculated using finite element method and the implicit time-integration method implemented in commercial codes. The boundary condition corresponding to dynamic loading was determined by deconvolution procedure. The error analysis showed that most precise signal reproduction is achieved while using target signal with peak value reduced by 40% as a test signal. Both acceleration and displacement time-series were successfully reproduced. Moreover, the stability analysis was conducted for five independent signals with design peak horizontal acceleration and showed that no permanent displacements should occur. The temporary horizontal displacement of the dam crest should not exceed 13 mm, assuming equivalent linear material model.

Resilient Self-Reproducing Systems

2008 ◽  
Author(s):  
Amor A. Menezes ◽  
Pierre T. Kabamba
Keyword(s):  
Large Scale ◽  
Failure Modes ◽  
Approaches To Learning ◽  
System Level ◽  
Reproductive Capacity ◽  
Reconfigurable Robots ◽  
Control Schemes ◽  
Learning And Adaptation ◽  
Payload Mass ◽  
System States

This paper is motivated by the need to minimize the payload mass required to establish an extraterrestrial robotic colony. One approach for this minimization is to deploy a colony consisting of individual robots capable of self-reproducing. An important consideration once such a colony is established is its resiliency to large-scale environment or state variations. Previous approaches to learning and adaptation in self-reconfigurable robots have utilized reinforcement learning, cellular automata, and distributed control schemes to achieve robust handling of failure modes at the modular level. This work considers self-reconfigurability at the system level, where each constituent robot is endowed with a self-reproductive capacity. Rather than focus on individual dynamics, the hypothesis is that resiliency in a collective may be achieved if: 1) individual robots are free to explore all options in their decision space, including self-reproduction, and 2) they dwell preferentially on the most favorable options. Through simulations, we demonstrate that a colony operating in accordance with this hypothesis is able to adapt to changes in the external environment, respond rapidly to applied disturbances and disruptions to the internal system states, and operate in the presence of uncertainty.

Modeling the System and Component Performance Interactions of a SOFC Based APU for Changes in Application Load: Transient Response and Control Strategy

2004 ◽  
Author(s):  
D. F. Rancruel ◽  
M. R. von Spakovsky
Keyword(s):  
Transient Response ◽  
Control Strategy ◽  
Control Strategies ◽  
Control Variable ◽  
System Level ◽  
System Component ◽  
System Response ◽  
Optimal Control Strategy ◽  
Synthesis Design ◽  
And Control

Solid-Oxide-Fuel-Cell (SOFC) stacks respond in seconds to changes in load while the balance of plant subsystem (BOPS) responds in times several orders of magnitude higher. This dichotomy diminishes the reliability and performance of SOFC electrodes with changes in load. In the same manner current and voltage ripples which result from particular power electronic subsystem (PES) topologies and operation produce a negative effect on the SOFC stack subsystem (SS) performance. The difference in transient response among the sub-systems must be approached in a way which makes operation of the entire system not only feasible but ensures that efficiency and power density, fuel utilization, fuel conversion, and system response are optimal at all load conditions. Thus, a need exists for the development of transient component- and system-level models of SOFC based auxiliary power units (APUs), i.e. coupled BOPS, SS, and PES, and the development of methodologies for optimizing subsystem responses and for investigating system-interaction issues. In fact the transient process occurring in a SOFC based APU should be systematically treated during the entire creative process of synthesis, design, and operational control, leading in its most general sense to a dynamic optimization problem. This entails finding an optimal system/component synthesis/design, taking into account on- and off-design operation, which in turn entails finding an optimal control strategy and control profile for each sub-system/component and control variable. Such an optimization minimizes an appropriate objective function while satisfying all system constraints. A preliminary set of chemical, thermal, electrochemical, electrical, and mechanical models based on first principles and validated with experimental data have been developed and implemented using a number of different platforms. These models have been integrated in order to be able to perform component, subsystem, and system analyses as well as develop optimal syntheses/designs and control strategies for transportation and stationary SOFC based APUs. Some pertinent results of these efforts are presented here.

KL Transform and Neural-Net Based Framework for Failure Modes Classification in Electronics Subjected to Mechanical-Shock

2011 ◽  
Author(s):  
Pradeep Lall ◽  
Prashant Gupta ◽  
Kai Goebel
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Learning Algorithm ◽  
Back Propagation ◽  
Feature Space ◽  
System Level ◽  
Neural Net ◽  
Mechanical Shock ◽  
Time Frequency ◽  
Damage Initiation

Electronic systems under extreme shock and vibration environments including shock and vibration may sustain several failure modes simultaneously. Previous experience of the authors indicates that the dominant failure modes experienced by packages in a drop and shock frame work are in the solder interconnects including cracks at the package and the board interface, pad cratering, copper trace fatigue, and bulk-failure in the solder joint. In this paper, a method has been presented for failure mode classification using a combination of Karhunen Loe´ve transform with parity-based stepwise supervised training of a perceptrons. Early classification of multiple failure modes in the pre-failure space using supervised neural networks in conjunction with Karhunen Loe´ve transform is new. Feature space has been formed by joint time frequency analysis. Since the cumulative damage may be accrued under repetitive loading with exposure to multiple shock events, the area array assemblies have been exposed to shock and feature vectors constructed to track damage initiation and progression. Error Back propagation learning algorithm has been used for stepwise parity of each particular failure mode. The classified failure modes and failure regions belonging to each particular failure modes in the feature space are also validated by simulation of the designed neural network used for parity of feature space. Statistical similarity and validation of different classified dominant failure modes is performed by multivariate analysis of variance and Hoteling’s T-square. The results of different classified dominant failure modes are also correlated with the experimental cross sections of the failed test assemblies. The methodology adopted in this paper can perform real-time fault monitoring with identification of specific dominant failure mode and is scalable to system level reliability.

Sign in / Sign up

Export Citation Format

Share Document