Identify Failure Modes Research Articles

Experimental determination of ballistic performance of newly developed multiaxis non-interlaced/non-Z E-glass/polyester and 3D woven carbon/epoxy composites with soft backing aramid fabric structures

The aim of this study is to understand the energy absorption mechanism and identified failure modes of the developed multiaxis non-interlaced/non-Z E-glass/polyester and 3D woven carbon/epoxy composite plates with soft backing para-aramid fabric structures. Two structures, multiaxis non-interlaced/non-Z E-glass/polyester composite plate and soft back layered para-aramid fabric, and 3D woven carbon/epoxy composite plate and multiaxis non-interlaced/non-Z E-glass/polyester composite plate with soft back layered para-aramid fabric, absorbed considerable impact energy when a high speed projectile’s metal jacketed section was stopped. The damage zones of both structures were investigated after impact. 3D woven carbon/epoxy plate showed a small damaged area compared to that of the non-interlaced/non-Z E-glass/polyester plate. This was because the Z-fiber suppressed the impact load, but the local area was severely damaged in the form of fiber and matrix breakages. There was no intra and inter fiber damage around the impacted area in the 3D carbon/epoxy composite plate, whereas there was intra and inter fiber damage around the impacted area in the non-interlaced/non-Z E-glass/polyester plate. It was thought that the impact load in the E-glass/polyester structure was redistributed around the local impacted area. Fiber damage in the soft back layered fabric extended from the decomposition of the fiber ends, partial and total fiber breakages to yarn pull-out and crimp recovery. Fiber decomposition results in friction between the fabric and the projectile which generates thermal load in the soft structure.

TU-D-BRB-02: Failure Modes and Effects Analysis Applied to HDR Treatment Planning

Purpose: To apply Failure Modes and Effects Analysis (FMEA) to HDR treatment planning in order to identify the most likely and significant sources of error in the process. Methods and Materials: We have made a list of 24 failure modes grouped into six categories (imaging, catheter reconstruction, dwell position activity, dose points/normalization, optimization/dose, and evaluation) based on our experience with the Nucletron Plato and Oncentra planning systems. Each mode was then rated on a 1–5 scale for severity, likelihood of occurrence, and probability of escaping detection. An overall ranking is formed from the product of the 3 scores (1–125). Severity was ranked according to potential harm to the patient (notably underdosing was not considered) and was based on the NCI Common Terminology Criteria for Adverse Events handbook v 4.0. The authors assigned scores independently and the resulting rankings were averaged. We have also analysed 36 recent reported medical events related to HDR treatment planning listed on the NRC website and compared with our own rankings. Results: Failure modes associated with image sets, catheter reconstruction, indexer length and incorrect dose points had the highest ranking in our analysis (scores > 20). The most often cited failure modes in the NRC reports examined were indexer length (17/36) and incorrect dose points (6/36). Several of our high‐ranking modes are not associated with reported events. Conclusion: It is a useful exercise to identify failure modes locally and analyse the efficacy of the local quality assurance program. Comparison with nationally reported failures can help direct the local analysis, but the absence or small number of reports for failure modes with a high score may be due to low detectability. Such modes obviously cannot be ignored.

構造最適設計における設計条件と設計手法の明確化のための系統的方法論

Structural design optimization has become an effective paradigm for designing and developing various kinds of products. However, it is not so popular in the electric appliances in spite of their small sizes and relatively simple configurations. This paper first reviews the design and development processes of electric appliances in which CAE-based design and optimization based design methods were to be utilized. It reveals that the identification of design specifications is fairly important as their prerequisites in the field of electric appliances. Then this paper proposes a strategic scheme for systematically identifying specifications for structural design optimization. The scheme is composed of Specification Priority Matrix (SPM), for identifying the antipathetic importance of feature, cost, time and reliability, Failure Mode and Condition Specification (FMCS), for extracting, categorizing and identifying failure modes and their critical ones, Design Approach Tree (DAT), for selecting an appropriate design approach based on the result of SPM and FMCS, etc. Finally, its effectiveness and validity are discussed by studying the past design and development cases.

Hysteretic Model for Reinforced Concrete Columns Including the Effect of Shear and Axial Load Failure

Recent strong earthquakes have shown that column failure is the primary cause of collapse in many existing older buildings and bridges. The main objective of this paper is to develop a macromodel to simulate the cyclic lateral load-deformation response of reinforced concrete columns with limited computational effort. Flexural, longitudinal bar slip, and shear deformations are predicted under monotonic lateral loads, including the effects of strength decay and stiffness degradation. Using these monotonic responses as envelopes or primary curves, cyclic responses corresponding to these three deformation components are calculated. The column under consideration is classified into one of five categories considering the potential for flexural, shear, or axial load failure. Individual cyclic responses then are combined to obtain the total lateral response of the column based on its identified failure mode. Comparison of predicted cyclic response and experimental data showed that the proposed model is sufficiently accurate.

Analyse von Verzögerungen der Schockraumdiagnostik bei Einsatz der Mehrschicht-Spiral-Computertomografie

In the case of major trauma, immediate recognition and treatment of life-threatening conditions are essential. An increasing number of European trauma centers use MSCT during the primary trauma survey due to its high diagnostic precision and speed. However, there is currently little empirical data about failures in this process to practice quality assurance. The aim of this study was to evaluate this process under operating resuscitation conditions and to identify failure modes that caused delays in completion. An independent study monitor documented the course of trauma room treatment during a 10-month period. The inclusion criteria were patients who were admitted directly from the accident scene and the study monitor was present at the time of admission. According to our ATLS-based trauma algorithm whole-body CT (WBCT) consists of non-contrast head CT (CCT) and contrast-enhanced trunk CT (TCT). 57 trauma patients receiving 45 WBCT. 5 single CCT and 4 single TCT studies were evaluated. After initial resuscitation, CCT was obtained within 17 min of trauma room admission (IQR 13.0 - 20.0). In 20 % (95 %CI 9 - 31 %) of the cases, a CCT delay of median 5.0 min (IQR 3.8 - 8.0) was observed caused by e. g. earings, piercings and ECG cables in the scan field or intoxicated patients. Contrast-enhanced TCT was performed after 23.0 min (IQR 19.0 - 27.0). Due to preventable errors 12 of the 49 TCT studies were delayed (25 % 95 %CI 12 - 37 %) for 5 min (IQR 3.0 - 8.0). Under "front line" conditions every fifth CCT and every fourth TCT study was completed with a median delay of 5 min. An independent process analysis revealed that unpreventable delays were due to uncooperative patients or system failure. Preventable delays were due to errors such as short intravenous lines or deviation from trauma room algorithms. Preventable delays could be avoided by addressing human and technical aspects such as revising checklists and functional architecture of the trauma bay. The failure mode and effect analysis (FMEA) method would assure quality in this process.

A Risk Analysis Method to Evaluate the Impact of a Computerized Provider Order Entry System on Patient Safety

ObjectivesQuantitative evaluation of safety after the implementation of a computerized provider order entry (CPOE) system, stratification of residual risks to drive future developments. DesignComparative risk analysis of the drug prescription process before and after the implementation of CPOE system, according to the Failure Modes, Effects and Criticality Analysis (FMECA) method. MeasurementsThe failure modes were defined and their criticality indices calculated on the basis of the likelihood of occurrence, potential severity for patients, and detection probability. Criticality indices of handwritten and electronic prescriptions were compared, the acceptability of residual risks was discussed. Further developments were proposed and their potential impact on the safety was estimated. ResultsThe sum of criticality indices of 27 identified failure modes was 3813 for the handwritten prescription, 2930 (−23%) for CPOE system, and 1658 (−57%) with 14 enhancements. The major safety improvements were observed for errors due to ambiguous, incomplete or illegible orders (−245 points), wrong dose determination (−217) and interactions (−196). Implementation of targeted pop-ups to remind treatment adaptation (−189), vital signs (−140), and automatic edition of documents needed for the dispensation (−126) were the most promising proposed improvements. ConclusionThe impact of a CPOE system on patient safety strongly depends on the implemented functions and their ergonomics. The use of risk analysis helps to quantitatively evaluate the relationship between a system and patient safety and to build a strategy for continuous quality improvement, by selecting the most appropriate improvements to the system.

Alookback - Quality and reliability facilitator- FMEA

Failure modes and effects analysis (FMEA) includes stress, reliability, environment, quality and duty-cycle factors, regardless of the application goal. During design, the FMEA primary objectives are to identify failure modes and to mitigate those failures through changes in design, processes, and materials. This column briefly explains the history and importance of FMEA and why entropy is the typical causes of failures during a product's lifetime.

Deformation and fracture modes of sandwich structures subjected to underwater impulsive loads

Sandwich panel structures with thin front faces and low relative density cores offer significant impulse mitigation possibilities provided panel fracture is avoided. Here steel square honeycomb and pyramidal truss core sandwich panels with core relative densities of 4% were made from a ductile stainless steel and tested under impulsive loads simulating underwater blasts. Fluid-structure interaction experiments were performed to (i) demonstrate the benefits of sandwich structures with respect to solid plates of equal weight per unit area, (ii) identify failure modes of such structures, and (iii) assess the accuracy of finite element models for simulating the dynamic structural response. Both sandwich structures showed a 30% reduction in the maximum panel deflection compared with a monolithic plate of identical mass per unit area. The failure modes consisted of core crushing, core node imprinting/punch through/tearing and stretching of the front face sheet for the pyramidal truss core panels. Finite element analyses, based on an orthotropic homogenized constitutive model, predict the overall structural response and in particular the maximum panel displacement.

Science-based MEMS reliability methodology

In cases where device numbers are limited, large statistical studies to verify reliability are impractical. Instead, an approach incorporating a solid base of modelling, simulation, and material science into a standard reliability methodology makes more sense and leads to a science-based reliability methodology. The basic reliability method is (a) design, model and fabricate, (b) test structures and devices, (c) identify failure modes and mechanisms, (d) develop predictive reliability models (accelerated aging), and (e) develop qualification methods. At various points in these steps technical data is required on MEMS material properties (residual stress, fracture strength, fatigue, etc.), MEMS surface characterization (stiction, friction, adhesion, role of coatings, etc.) or MEMS modelling and simulation (finite element, analysis, uncertainty analysis, etc.). This methodology is discussed as it relates to reliability testing of a micro-mirror array consisting of 144-piston mirrors. In this case, 140 mirrors were cycled full stroke (1.5 μm) 26 billion times with no failure. Using our technical science base, fatigue of the springs was eliminated as a mechanism of concern. Eliminating this wear-out mechanism allowed use of the exponential statistical model to predict lower bound confidence levels for failure rate in a “no-fail” condition.

CLASSIFICATION AND ANALYSIS OF FAILURE MODES FOR TIME-TRIGGERED SYSTEMS

A main step in evaluating reliability and safety properties of embedded communication systems consists in identifying potential failure modes. We present a classification of component and system level failure modes for time-triggered communication networks, such as TTP and FlexRay. Based on our experience in modeling and verifying industrial real-time systems, we propose a way to analyze the effect of these failure modes on a given system using the SAL framework. We discuss two modeling paradigms that are particularly suitable for time-triggered communication networks. These paradigms differ in the way time is represented, either as a discrete or a continuous variable. Moreover, we identify failure modes that can be represented by both modeling approaches, as well as failure modes that require a continuous representation.

Performance Characterization of a Rover Navigation Algorithm Using Large‐Scale Simulation

Autonomous rover navigation is a critical technology for robotic exploration of Mars. Simulation allows more extensive testing of such technologies than would be possible with hardware test beds alone. A large number of simulations, running in parallel, can test an algorithm under many different operating conditions to quickly identify the operational envelope of the technology and identify failure modes that were not discovered in more limited testing. GESTALT is the autonomous navigation algorithm developed for NASA′s Mars rovers. ROAMS is a rover simulator developed to support the Mars program. We have integrated GESTALT into ROAMS to test closed‐loop, autonomous navigation in simulation. We have developed a prototype capability to run many copies of ROAMS in parallel on a supercomputer, varying input parameters to rapidly explore GESTALT′s performance across a parameter space. Using these tools, we have demonstrated that large scale simulation can identify performance limits and unexpected behaviors in an algorithm. Such parallel simulation was able to test approximately 500 parameter combinations in the time required for a single test on a hardware test bed.

Using HFMEA to Assess Potential for Patient Harm from Tubing Misconnections

Reported cases of tubing misconnections and other tubing errors prompted Columbus Children's Hospital to study their potential for harm in its patient population. A Health Failure Mode and Effects Analysis (HFMEA) was conducted in October 2004 to determine the risks inherent in the use and labeling of various enteral, parenteral, and other tubing types in patient care and the potential for patient harm. An assessment of the practice culture revealed considerable variability among nurses and respiratory therapists within and between units. Work on an HFMEA culminated in recommendations of risk reduction strategies. These included standardizing the process of labeling of tubing throughout the organization, developing an online pictorial catalog to list available tubing supplies with all aliases used by staff, and conducting an inventory of all supplies to identify products that need to be purchased or discontinued. Three groups are working on implementing each of the recommendations. Most of the results already realized occurred in labeling of tubing. The pediatric intensive care unit labels all tubing with infused medications 85% of the time; tubings inserted during surgery or in interventional radiology are labeled 53% and 93% of the time. Pocket-size cards with printed labels were tested in three units. This proactive risk assessment project has identified failure modes and possible causes and solutions; several recommendations have been implemented. No tubing misconnections have been reported.

Traceability and quality assurance systems in food supply chains

Purpose of the review: O ver the past 5 years, numerous regulations have been drawn up and implemented, which have had a direct im pact on f ood sale from very s mall and medium-sized enterprises, as well as between countries. These activities require cont inuous monitoring by inspection agencies on trade policy, safety and risks analysis, with stringent management practices an d precaution readiness for emergencies. Food safety, quality, clai m validity and proof-of-origin are important for fresh produce , both for clients and customers locally or abroad. As a result, various governmental inspection services and third-party certification age ncies are available for regulat ing the export and import of food commodities. Today, we are facing globalisation of our food-s upply chains. This article foc uses on better understanding and defining food quality, entities and system components. New tools t o identify failure mode and effic iency in processes, as well as practical cases of traceability are referenced and und er v alidation. Directions for future research: Im proving technological skills and competency, as well as training in engineering, applied scien ce and technology, computer technology, economics and logistics must become high priority in relation to food quality, safety, and failure a nalysis on systems relevant to traceability dom ains. Very little or no benchmarking is performed or accessib le to the industry. More research and ad aptation is needed on modelling entity-relation and quality, in combination with sensors an d advanced computing. Setting up interactive associations on traceab ility, computer science, econ omics, efficient logistics, as well as s haring on a common hub, expertise and problematic cases wo uld speed up international efforts to produce and trade safe pr oduce. Creating and making automatic identification and data capture information technology available at regional and nat ional centres, where producers, processors, distributors and inspection agencies would bring in or improve confidence levels an d, secure access to data, know-how, and practical training and a dvice is of utmost im portance. These are challenging prospects fo r all parties involved in agri-food safety.

Advanced Fault Isolation and Failure Analysis Techniques for Future Package Technologies

As next-generation package technologies become more complex, the isolation of defects and their failure analysis has became more challenging. The complexity of newgeneration packages, driven by Moore’s Law, include a greater number of components allocated to smaller form factors, thus creating defects that are difficult to isolate and characterize, such as metal migration, dendrite growth, microcracks, wirebond microfractures, plane-toplane shorting, high-resistance, defects in multistacked dice, via delamination, and bump bridging. A continued effort has been made to close these technical gaps in analytical tools and techniques. By guiding and codeveloping next-generation analytical tools, we have been able to successfully identify failure modes and root causes to rapidly advance unique and new solutions at Intel in current package technologies. In this paper we discuss how these tools are being used in the failure analysis flow, as well as the technical gaps that have to be addressed in order to meet the fault isolation and failure analysis challenges of next-generation package technologies.

Use of a prospective risk analysis method to improve the safety of the cancer chemotherapy process

To perform a risk analysis of the cancer chemotherapy process, by comparing five different organizations. To quantitatively demonstrate the usefulness of centralization and information technologies, to identify residual risks that may be the target of additional actions. A reengineering of the process started in 1999 and was planned to be finished in 2006. The analysis was performed after the centralization and at the beginning of information technologies integration. Two thousand two hundred beds university hospital, with medical, surgical, haematological, gynaecological, geriatric, paediatric oncological departments. Twelve thousand cancer chemotherapies each year. According to the failure modes, effects and criticality analysis (FMECA) method, the failure modes were defined and their criticality indexes were calculated on the basis of the likelihood of occurrence, the potential severity for the patients, and the detection probability. Criticality indexes were compared and the acceptability of residual risks was evaluated. The sum of criticality indexes of 27 identified failure modes was 3596 for the decentralized phase, 2682 for centralization, 2385 for electronic prescription, 2081 for electronic production control, and 1824 for bedside scanning (49% global reduction). The greatest improvements concerned the risk of errors in the production protocols (by a factor of 48), followed by readability problems during transmission (14) and product/dose errors during the production (8). Among the six criticality indexes remaining superior to 100 in the final process, two were judged to be acceptable, whereas further improvements were planned for the four others. Centralization to the pharmacy was associated with a strong improvement but additional developments involving information technologies also contributed to a major risk reduction. A cost-effect analysis confirmed the pertinence of all developments, as the cost per gained criticality point remained stable all over the different phases.

Failure of sandwich beams consisting of alumina face sheet and aluminum foam core in bending

Applications of sandwich structures, comprising alumina face sheets and aluminum foam core, depend critically on their mechanical performance. Four point bend tests are performed on sandwich beams with varying geometries to identify competing failure modes, such as core indentation, face sheet cracking and core shear. Analytical formulae for the identified failure modes are obtained. A failure mode map was constructed based on the analytical calculations in the non-dimensional parameters of beam geometry for a given face sheet to core strength ratio. The tested geometries are simulated using a finite element program: the beam stiffness and the failure load calculations were found to be in good agreement with the experimental and analytical results within experimental scatter.

QRA Study of an Activated Carbon Filter Safeguard System

The Mary Kay O’Connor Process Safety Center (MKOPSC) at Texas A&M University conducted a Quantitative Risk Analysis (QRA) for subsystems of the VX neutralization process. The process is conducted in a negative pressure containment system. The very large air handling system also acts to direct any fugitive emissions or small leaks to the carbon adsorption filter systems, the final safeguard in preventing highly toxic chemicals from escaping to the atmosphere. The activated carbon filter system concentrates the low level fugitive emissions, thereby creating a potential for a more significant catastrophic release if the carbon filter system fails. The risk tradeoff between capturing low-level fugitive emissions and the potential for a large-scale toxic chemical release must be compared. The fault trees for the air handling system and the carbon filter systems are highlighted. In particular, the uncertainty in the reliability data and their respective impact on the overall failure rate and system availability are emphasized. The importance of this study was to point out a specific failure mode that was not adequately addressed with safeguards in the original process design, thereby creating an unacceptable risk and requiring additional safeguards. The study also verified that the safeguards in the original design for all other identified failure modes reduced the risks to generally acceptable levels.

FAULT DIAGNOSIS OF ELECTROHYDRAULIC SYSTEMS

Reliability is essential for electro-hydraulic systems due to the high energy densities associated with their operation. A failure can have catastrophic results, for example, if a contamination failure of hydraulic fluid at high pressure occurs. A novel approach for fault diagnosis of hydraulic systems has been proposed, using genetic algorithms as the parameter optimization method, and model based simulation. Performance tracking of critical parameters within the hydraulic system assesses subtle state changes and attempts to identify failure modes associated with these state changes. The proposed approach, which requires analysis of each component of the hydraulic system under normal operation and with specific, induced failure modes, has been successfully applied to a hydraulic system incorporating a servovalve and linear actuator. The results of this study provide a basis for future studies of more complex hydraulic components and systems.

Ballistic Impact of Braided Composites with a Soft Projectile

Impact tests using a soft gelatin projectile were performed to identify failure modes that occur at high strain energy density during impact loading. Failure modes were identified for aluminum plates and for composites plates and half-rings made from triaxial carbon fiber braid having a 0∕±60° architecture. For aluminum plates, a large hole formed as a result of crack propagation from the initiation site at the center of the plate. For composite plates, fiber tensile failure occurred in the back ply at the center of the plate. Cracks then propagated from this site along the ±60° fiber directions until triangular flaps opened to form a hole. For composite half-rings fabricated with 0° fibers aligned circumferentially, fiber tensile failure also occurred in the back ply. Cracks first propagated from this site perpendicular the 0° fibers. The cracks then turned to follow the ±60° fibers and 0° fibers until rectangular flaps opened to form a hole. Damage in the composites was localized near the impact site, w...

고분자 압전센서 신호를 이용한 스마트 복합적층판의 충격 손상 규명

An experimental procedure to identify failure modes of impact damage using sensor signals and to analyze their general features is examined. A series of low-velocity impact tests from low energy to damage-induced high energy were performed on the instrumented drop weight impact tester to monitor the stress wave signals due to failure modes such as matrix cracking, delamination, and fiber breakage. The wavelet transform(WT) and Short Time Fourier Transform(STFT) are used to decompose the piezoelectric sensor signals in this study. The extent of the damage in each case was examined by means of a conventional ultrasonic C-scan. The PVDF sensor signals are shown to carry important information regarding the nature of the impact process that can be extracted from the careful signal processing and analysis.