Incremental Failure Research Articles

Experimental study on the dynamic properties of soft clay with sand interlayers under cyclic loading

Unlike uniform soils, soft clays with sand interlayers in coastal soft clays, can affect their mechanical properties, potentially impacting underground-construction safety and stability. Consolidated undrained cyclic triaxial tests were conducted to study the dynamic properties and deformation behavior of clay, focusing on how the thickness ratio between the sand and clay layers and the cyclic-stress ratio influence the pore pressure, axial strain, shear-modulus ratio, and normalized damping ratio. The results indicate that higher thickness ratios and cyclic-stress ratios lead to a faster decay of the shear-modulus ratio, quicker increases in pore pressure, faster strain accumulation, and fewer cycles to failure. The normalized damping ratio has three different forms: decreasing, decreasing then increasing, and increasing. However, at a cyclic-stress ratio of 0.2 and thickness ratio of 0.25, the samples exhibit better dynamic characteristics. Soft clay with sand layers exhibits characteristics in line with the stability theory. At low thickness and cyclic-stress ratios, purely elastic and elastically stable phases are observed. As the thickness and cyclic-stress ratios increase, it transitions to plastic stability and incremental failure.

Damage behavior of cold-rolled sintered fiber felts

Porous Materials, such as sintered fiber felts (SFFs), can contribute to the reduction of aircraft noise by acting as a low-noise trailing edge (TE). A rolling process with a time-varying rolling gap was sucessfully used to tailor the aeroacoustic properties of SFFs. To ensure the suitability of rolled porous materials for application, the mechanical properties after rolling must be investigated. The objective of this study was to clarify the effect of the rolling process on the damage evolution during tensile loading. A SFF consisting of a functional layer and a support grid made of alloy 1.4404 was used for rolling. Interrupted tensile tests in combination with computed tomography (CT) were used to investigate the damage evolution of as-received material, uniformly rolled material and material rolled with a gradient in thickness reduction. Metallographic examination and fracture surface analysis using scanning electron microscopy (SEM) complemented the CT analysis. Uniformly rolled material with a low degree of deformation (−0.74 ≤ φ < 0) failed identically to the as-received material. The functional layer failed first, starting from the center. The support grid subsequently failed due to the incremental failure of individual wires. The material rolled with a gradient in thickness reduction failed accordingly. A significant change in damage evolution occured for material rolled at high degrees of deformation φ ≤ −1.53, where the support grid fails first and the functional layer second. The rolling process using a time-varying rolling gap does not result in a detrimental mechanical behavior under tensile load. The results improve the general understanding of the effects of rolling processes on the properties of porous materials and allow the damage behavior to be taken into account with regard to its application as a TE.

Study on dynamic characteristics of salinized silt under cyclic loading.

Under the repeated action of aircraft taxiing load, the subgrade plastic deformation becomes the key factor affecting the service performance of the airfields when salinized silt is used to fill the subgrade. In this study, the dynamic triaxial tests were carried out on a region in the northern part of China to study the effects of different salt contents on the dynamic characteristics of silt under cyclic loading. A prediction model for the salinized silt dynamic strength with a plastic strain of 4% as the failure criterion for the subgrade was thus proposed. It is found that with the increase of dynamic stress amplitude, the salinized silt plastic deformation transforms gradually from plastic deformation to incremental failure. The salt contents significantly influence the plastic strain and critical dynamic stress of silt. The strength of the salinized silt specimen is related to the ion concentration in the soil pores and the arrangement pattern of soil particles, as indicated by the progressive strength increase of the salinized silt at the low salt content of 1% and a further gradual decrease at high salt content.

Cyclic True Triaxial Tests on Aeolian Sand Considering Initial Shear Effect

Under traffic loading, the soil elements in subgrade are subjected to a complex 3D stress path. To investigate the cyclic behavior of desert subgrade under initial shear stress conditions, the number of cyclic true triaxial tests were implemented on aeolian sand from the Tengger Desert. A large range of initial shear stress levels and different cyclic stress paths (various combinations of cyclic major and intermediate principal stresses) were designed in the experiments. The results show that the initial shear stress level significantly influences the cyclic response, and the response mode of aeolian sand under initial shear stress is incremental failure and elastic shakedown, while it is critical failure without initial shear stress. With the increase in initial shear stress, the permanent strain increases first and then decreases, with the maximum permanent strain occurring at q0 = 50 kPa. Moreover, by comparing the test data under different cyclic stress paths, it is found that the cyclic resistance decreases with the increase in the coefficient of cyclic intermediate principal stress bcyc. Compared to the limiting pore pressure criterion, the conventional 5% axial strain failure criterion may overestimate the cyclic resistance, leading to unsafe evaluation and design. Therefore, by using the pore pressure criterion, the relationship between the limit pore pressure ratio and the initial stress condition was investigated and it was found that the limit pore pressure ratio decreased linearly when the initial shear stress increased.

Subset simulation based approach for space-time-dependent system reliability analysis of corroding pipelines

This paper proposes a subset simulation (SS) based approach for space and time-dependent reliability analysis of corroding pipelines. It is assumed that the pipeline can fail either due to leakage and/or burst. We propose two distinct approaches for tackling the problem. In the first approach, we treat the problem as a time-variant system reliability problem. The problem is formulated as a series system where failure at one of the defect locations will result in failure of the pipeline. This approach is particularly suitable when there are only a limited number of corrosion defects. In the second approach, the reliability analysis problem is treated as a ‘space-time variant’ reliability analysis problem. This approach is particularly suitable when exact knowledge about the number of defects is not available. In both the approaches, the time-dependent probability of failure is represented in an auto-regressive form such that the probability of failure at a given time can be computed based on the probability of failure at the previous time and an incremental failure probability. A simple composite limit-state function is proposed for computing the incremental failure probability. SS is used for computing the initial and incremental failure probabilities. To illustrate performance of the proposed approach, four pipeline problems representing different scenarios are considered. For all cases, the proposed approach is found to yield highly accurate results.

Unionization and IPO Underpricing

This paper investigates the impact of labor unionization on IPO underpricing. We demonstrate that the existence of unions reduces underpricing by 11.20%. Unionized IPOs are associated with downward offer-price revisions, higher cost of capital, inferior firm-operating performance, and incremental failure risk. We argue that union presence discourages investor participation, since investors discount the value of unionized IPOs. We conclude that labor unionization is an important factor in IPO pricing and first-day returns. Our findings are of particular interest to managers, labor unionists, and market participants.

A neural network approach for the analysis of limit bearing capacity of continuous beams depending on the character of the load

Being a part of civil engineering, limit state analysis represents a structural analysis with a goal of developing efficient methods to directly estimate collapse load for a particular structural model. As a theoretical foundation, limit state analysis uses a set of bound (limit) theorems. Limit theorems are based on the law of conservation of energy and are used for a direct definition of the limit state function for failure by plastic collapse or by inadaptation. This study proposes an artificial neural network (ANN) model in order to approximate the residual bending moment, limit and the incremental failure force of continuous beams. The neural network structure applied here is a radial-Gaussian network architecture (RGIN) and complementary training procedure. This structure is intended to be used for civil engineering purposes and it is demonstrated on the example of the two-span continuous beam loaded in the middle of the span that the limit and the incremental failure force can be obtained using neural network approach with sufficient precision and is especially suitable in analysis when some of the model parameters are variable.

In Search of the Missing Ingredient: Religious Slaughter, Incremental Failure, and the Quest for the Right to Know: A Response to Anna Joseph

Abstract This article examines Anna Joseph’s (2016) suggestion of introducing into United States law a requirement to stun an animal still found to be conscious after 40 seconds following initial cutting during religious slaughter. It is suggested that the proposed law fails to address significant ethical concerns based on scientific evidence. The conflict with human rights legislation, especially religious freedom, is discussed. A new consumers’ rights approach is proposed that highlights the life of the animal and may provide a universally applicable legal framework for meat production. This may avoid the pitfalls of conflicting with human rights, thereby enabling the revision of practices through education, information, and changing consumer behavior.

Avalanche Capability of Vertical GaN p-n Junctions on Bulk GaN Substrates

Inductive avalanche test results presented in this letter demonstrate that GaN p-n diodes can sustain single-pulse and repetitive inductive avalanche currents. The 0.36-mm2 vertical GaN p-n diodes can sustain single-pulse avalanche currents as high as 10 A. The safe zone of the single-pulse avalanche current is limited by peak pulse power and energy deposited in the device. The temperature-dependent behavior of the breakdown voltage and the reverse-voltage at onset of avalanche has a positive temperature coefficient. Repetitive avalanche ruggedness testing was performed by applying $10^{\mathrm {5}}$ pulses at 5-kHz frequency with increasing repetitive stress current. Based on a population of 63 devices, the incremental failure rate under repetitive avalanche current increases with increasing avalanche current. The devices that survive the step stress test sustain no parametric drift under repetitive avalanche.

Cost-effectiveness analysis of fixation options for intertrochanteric hip fractures.

Intertrochanteric hip fractures are a major source of morbidity and financial burden, accounting for 7% of osteoporotic fractures and costing nearly $6 billion annually in the United States. Traditionally, "stable" fracture patterns have been treated with an extramedullary sliding hip screw whereas "unstable" patterns have been treated with the more expensive intramedullary nail. The purpose of this study was to identify parameters to guide cost-effective implant choices with use of decision-analysis techniques to model these common clinical scenarios. An expected-value decision-analysis model was constructed to estimate the total costs and health utility based on the choice of a sliding hip screw or an intramedullary nail for fixation of an intertrochanteric hip fracture. Values for critical parameters, such as fixation failure rate, were derived from the literature. Three scenarios were evaluated: (1) a clearly stable fracture (AO type 31-A1), (2) a clearly unstable fracture (A3), or (3) a fracture with questionable stability (A2). Sensitivity analysis was performed to test the validity of the model. The fixation failure rate and implant cost were the most important factors in determining implant choice. When the incremental cost for the intramedullary nail was set at the median value ($1200), intramedullary nailing had an incremental cost-effectiveness ratio of $50,000/quality-adjusted life year when the incremental failure rate of sliding hip screws was 1.9%. When the incremental failure rate of sliding hip screws was >5.0%, intramedullary nails dominated with lower cost and better health outcomes. The sliding hip screw was always more cost-effective for A1 fractures, and the intramedullary nail always dominated for A3 fractures. As for A2 fractures, the sliding hip screw was cost-effective in 70% of the cases, although this was highly sensitive to the failure rate. Sliding hip screw fixation is likely more cost-effective for stable intertrochanteric fractures (A1) or those with questionable stability (A2), whereas intramedullary nail fixation is more cost-effective for reverse obliquity fractures (A3). These conclusions are highly sensitive to the fixation failure rate, which was the major influence on the model results.

The European Debt Crisis: Incremental Reform, Austerity, and Institutional Failure

This article focuses on the way a crisis needs an institutional actor and champion. Through painfully slow intervention and muddling through, the European Central Bank (ECB) created new policy space for a European financial and banking system that was on the point of collapse. However, the institutional commitment to austerity and deep cuts to state spending have pushed the goal of a stronger federal union farther away than ever. This article examines the strengths and limitations of institutional “ad hocery” of making policy on the go. It also has a comparative examination of the Canadian experience with policy ad hocery during Canada's long-running constitutional wars between 1960 and 2000. In the end, Ottawa's strategy left the Canadian federal union decentralized and much more fragile. It makes the case that despite the accomplishment of keeping European capitalism afloat with massive and repeated bailouts of public money, the worst-case scenario facing the Eurozone of some kind of collapse in the near future is still on the table.

Repetitive bypass and revisions with extensions for limb salvage after multiple previous failures

The optimal treatment of patients facing imminent amputation after multiple (≥ 2) failed prior ipsilateral bypasses is unclear. We analyzed a group of patients undergoing multiple lower extremity bypasses for limb salvage to assess the utility of attempting multiple revascularizations. From 1990 to 2005, 105 revascularization procedures were performed in 55 limbs of 54 patients with imminent limb-threatening lower extremity ischemia after failure of ≥ 2 prior infrainguinal bypasses in the same leg. Fifty-five operations were the third procedure (Group A) and 50 operations were the fourth or more (Group B). We compared primary/secondary patency and limb salvage rates by Society for Vascular Surgery criteria. Limb salvage rates did not differ between patients undergoing a third bypass and those undergoing four or more bypasses at one year (62 versus 65%, NS) or at three years (58 versus 61%, NS). Secondary patency was not different between groups (76 versus 76%, P = NS) at one and three years (71 versus 70%, NS). Primary patency also did not differ between the two groups, at one year (24 versus 35%, NS), or at three years (11 versus 15%, NS). No differences were observed in morbidity and mortality rates between the groups. In conclusion, the likelihood of success of repetitive limb revascularization was unrelated to the number of previous failures. The expected incremental failure rate with each successive bypass was not found. These results, coupled with the three-year limb salvage rate of over 50% in patients who otherwise would have required amputation, lend support to aggressive use of limb revascularization in selected patients even after two or more failed bypasses.

Failure mechanisms of roof sheathing under fluctuating wind loads

Roof sheathing on typical North American timber frame house construction is subjected to high uplift loads during severe windstorms resulting in commonly observed failures. To investigate such failures in detail, ramp and fluctuating wind loads were applied to oriented strand board and plywood panels fixed to rafters with twisted and ring-shank nail varieties, as well as staples. It was observed for panels fixed with twist-shank nails that the panels separate from the rafters in small increments associated with the large peak pressures. In contrast, the failure progression for ring-shank nails is much more sudden. With both types of failure progression, however, it is observed that it is the short duration peak gusts which damage and fail the panels, and always at the nails with the largest tributary areas in the interior of the panel. Tests were also conducted with different missing nail configurations and the capacities assessed. It was observed that fasteners with the incremental failure mechanism were able to more effectively distribute the load such that the effects of missing nails are reduced compared to the panels which fail by the sudden mechanism.

Probability-Based Prediction of Degrading Dynamic Systems

This paper presents a methodology to provide the cumulative failure distribution (CDF) for degrading, uncertain, and dynamic systems. The uniqueness and novelty of the methodology is that long service time over which degradation occurs has been augmented with much shorter cycle time over which there is uncertainty in the system dynamics due to uncertain design variables. The significance of the proposed methodology is that it sets the foundation for setting realistic life-cycle management policies for dynamic systems. The methodology first replaces the implicit mechanistic model with a simple explicit meta-model with the help of design of experiments and singular value decomposition, then transforms the dynamic, time variant, probabilistic problem into a sequence of time invariant steady-state probability problems using cycle-time performance measures and discrete service time, and finally, builds the CDF as the summation of the incremental service-time failure probabilities over the planned life time. For multiple failure modes and multiple discrete service times, set theory establishes a sequence of true incremental failure regions. A practical implementation of the theory requires only two contiguous service-times. Probabilities may be evaluated by any convenient method, such as Monte Carlo and the first-order reliability method. Error analysis provides ways to control errors with regards to probability calculations and meta-model fitting. A case study of a common servo-control mechanism shows that the new methodology is sufficiently fast for design purposes and sufficiently accurate for engineering applications.

Muddling through in innovation — On incremental failure in developing an engine

Researchers often use Lindblom's concept of “muddling through” to explain how complex and incremental processes can lead to satisfactory results even without the systematic application of “management”. However, this tendency to look for positive outcomes from muddling might be limiting, as this tends to ignore muddling that ends in failure. This article aims to extend the work following Lindblom by studying the failure of an innovation in engine technology. The key argument is that by paying more attention to failures, business research can develop a more complete theory of muddling through, and this article uses the case of how a new engine for lawnmowers incrementally failed to become an innovation as an illustration. In this, the term “sliding” is introduced to clarify the role of incrementalism in the processual study of business failure.

The set-theory method for systems reliability of structures with degrading components

The times and frequencies of inspection, maintenance and replacement in structural systems are complicated by uncertain degradation rates of structural characteristics. Although degradation work at the component, or single failure mode level, is ongoing, this paper presents a method for assessing systems reliability where failure events may be described by time-variant parallel and/or series systems. Herein the models for the degradation rates contain random variables and time. For multiple failure modes and a sequence of discrete times, set theory establishes the true incremental failure region that emerges from a safe region. Probabilities via Monte-Carlo simulation require only time-invariant calculations. The cumulative failure distribution is the summation of the incremental failure probabilities. A practical implementation of the theory requires only two contiguous times. Error analysis suggests ways to predict and minimize errors so the method appears sufficiently accurate for engineering applications. Two structures with elastic–brittle material and time-invariant loads show the details of the method and the potential of the approach. It is shown that the proposed method provides a more realistic and efficient way to predict systems reliability than path-tracing methods that are available in the open literature.

Hepatic and Renal Failure after Anterior Myocardial Infarction Induced Apical Ventricular Septal Defect

We report the case of a 68-year-old man suffering from incremental hepatic and renal failure one month after anterior myocardial infarction. Cardiac MRI showed a pronounced apical post-AMI aneurysm, a moderate to severe mitral and tricuspid regurgitation as well as a hemodynamically highly significant 12 mm apical ventricular septal defect with a left-to-right ventricular shunt of almost 63% as the underlying cause. Heart X-ray revealed a severe LAD in-stent restenosis. CAPD catheter drainage of hydroperitoneum due to congestive liver and renal failure was provided in combination with intensified CAPD hemodialysis. Heart surgery was performed where the apical aneurysm was excised, the mitral valve was reconstructed, the IVSD was closed and the subtotally in-stent occluded LAD was bypassed. Post-surgery, the ascites were significantly reduced, and CAPD hemodialysis therapy could be terminated since the renal function gradually improved (MDRD = 25 mL/min). To our knowledge, for the first time we report successful CAPD catheter drainage of hydroperitoneum in combination with CAPD hemodialysis.

A New Sample-Based Approach to Predict System Performance Reliability

Multiple degradation paths arise when systems operate under uncontrolled, uncertain environmental conditions at customers' hands in the field. This paper presents a design stage method for assessing performance reliability of systems with competing time-variant responses due to components with uncertain degradation rates. Herein, system performance measures (e.g. selected responses) are related to their critical levels by time dependent limit-state functions. System failure is defined as the non-conformance of any response, and hence unions of the multiple failure regions are formed. For discrete time, set theory establishes the minimum union size needed to identify a true incremental failure region that emerges from a safe region. A cumulative failure distribution function is built by summing incremental failure probabilities. A practical implementation of the theory is manifest through evaluating probabilities by Monte Carlo simulation. Error analysis suggests ways to predict and minimize errors. An electrical temperature controller shows the details of the method, and the potential of the approach. It is shown that the proposed method provides a more realistic way to predict performance reliability than either worst-case, or simple average-based approaches that are available in the open literature.

QUALITY AND PERFORMANCE RELIABILITY ASSESSMENT OF MULTI-RESPONSE DEGRADING SYSTEMS

This paper presents a non-sampling based method for the simultaneous evaluation of quality and performance reliability of engineering systems with multiple time-variant responses due to multiple degrading components. This work provides a platform for robust design of degrading systems. The system performance degradations are related to component degradations using mechanistic models. The system soft failure is defined as the non-conformance of any response with respect to critical levels and such relations are easily modeled as time dependent limit-state functions. Then, for discrete time it is shown that an incremental failure set that emerges from a safe region can be written using only a pair of successive system instantaneous failure sets. The cumulative distribution function of soft failure is built by summing the incremental failure probabilities. A practical implementation of the proposed method can be manifest by first-order reliability methods (FORM) and second-order bounds. The proposed method can be used to assess initial quality and performance reliability of systems with combinations of designated means and tolerances. Examples of electro mechanical systems show the details of the formulation and the potential of the approach. Error sources and their magnitudes are discussed.

Set theoretic formulation of performance reliability of multiple response time‐variant systems due to degradations in system components

AbstractThis paper presents a design stage method for assessing performance reliability of systems with multiple time‐variant responses due to component degradation. Herein the system component degradation profiles over time are assumed to be known and the degradation of the system is related to component degradation using mechanistic models. Selected performance measures (e.g. responses) are related to their critical levels by time‐dependent limit‐state functions. System failure is defined as the non‐conformance of any response and unions of the multiple failure regions are required. For discrete time, set theory establishes the minimum union size needed to identify a true incremental failure region. A cumulative failure distribution function is built by summing incremental failure probabilities. A practical implementation of the theory can be manifest by approximating the probability of the unions by second‐order bounds. Further, for numerical efficiency probabilities are evaluated by first‐order reliability methods (FORM). The presented method is quite different from Monte Carlo sampling methods. The proposed method can be used to assess mean and tolerance design through simultaneous evaluation of quality and performance reliability. The work herein sets the foundation for an optimization method to control both quality and performance reliability and thus, for example, estimate warranty costs and product recall. An example from power engineering shows the details of the proposed method and the potential of the approach. Copyright © 2006 John Wiley &amp; Sons, Ltd.