Failure Path Research Articles

Multi-Scale Nonlinear Progressive Damage and Failure Analysis for Open-Hole Composite Laminates

In order to study the nonlinear behaviors and interactions among the constituents for the composite material structure under the tensile load, multiscale damage model using generalized method of cells (GMC) and a lamina-level progressive damage model were established, respectively, for fiber reinforced composite laminates with a central hole, which were based on the thermodynamic Schapery Theory (ST) at either the micro-level or the lamina level. Once the nonlinear progressive degradation of the matrix material reached the lower limit value for the ST method, matrix failures naturally occurred, the failure of the fiber was determined by the maximum stress failure criterion. For the multiscale progressive damage model, the GMC model consisting of a fiber subcell and three matrix subcells was imposed at each integral point of FEM elements, and the three matrix subcells undergo independent damage evolution. The load versus displacement curves and failure modes of the open-hole laminates were predicted by using the two progressive failure models, and the results were compared with that obtained by the Hashin-Rotem progressive failure model and the experimental results. The results show that the ST based method can obtain the nonlinear progressive damage evolution states and failure states of the composite at both the lamina level and the multiscale level. Finally, the damage contours and failure paths obtained are also presented.

A study on improving the mechanical performance by controlling the halo ring in the Q&P 980 steel resistance spot welds

This study focuses on improving the mechanical performance of third-generation Q&P steel resistance spot welds using a double-pulse welding cycle. Single and double-pulse welding schedules were implemented to assess the mechanical performance of the welds. Single-pulse welds exhibited poor cross-tension strength (CTS) values, failed around the fusion zone, and were accompanied by poor energy absorption capability. However, the double-pulse schedule showed improved CTS values by 33%, with an associated 110% increase in absorbed energy. The failure path observed from interrupted cross-tension tests showed that, in welds made using both pulsing schedules, failure proceeded along the fusion boundary and CGHAZ. In the single-pulse welds failed in brittle fashion, whereas the welds made with a double-pulse schedule exhibited a mixed (ductile and brittle) fracture morphology. The high-density microhardness mapping confirmed the presence of a localized softened zone (halo ring) adjacent to the fusion boundary in single-pulse welds. Strong elemental partitioning of Mn, Si, and C in the vicinity of the fusion boundary during long welding time was the primary cause for the halo formation. However, the halo ring was eliminated by performing a double-pulse weld schedule with 30 ms cooling time in between pulses; resulting in improved mechanical properties.

Reliability assessment of existing concrete bridges under the passage of heavy trucks considering bending–shear interaction

As trucks become heavy more frequently in current freight transportation, assessing the structural safety of bridges has become important. However, existing studies focus on the bridge performance subjected to bending or shear failure, neglecting the coupled mechanical behavior of bending–shear interaction. This paper proposes a numerical framework to evaluate the reliability of the existing concrete bridges under the passage of heavy trucks considering bending–shear interaction. First, the probabilistic coupled bending-shear resistances are developed using the modified compressive field theory. Then, a representative overloaded truck model, as well as random truck traffic, is constructed using measured weigh-in-motion data from Chinese freeways. Thereafter, a novel failure path approach based on the minimum distance increment between the total load effect route and resistance envelope curve is presented, which largely simplifies the analysis of bending–shear interaction to a one-dimensional decoupled issue. Finally, the reliability of the bridge is evaluated with respect to single (bending or shear) and coupled (bending–shear) failure modes. The results indicate that the coupled moment–shear failure is more severe than the single failure mode, implying the significance of considering the moment–shear interaction for the safety assessment of girder bridges.

Fatigue crack growth in the re-entrant auxetic structure

The investigation of fatigue behaviour of the re-entrant and rotated re-entrant auxetic specimens made of Al-alloy 7075-T651 is presented in this study. In the proposed work, the influence of the orientation of the unit cell on the crack path and fatigue life were studied by using both experimental and computational approaches. In the experimental and computational approach, two geometric layouts of the base unit cell were analysed (re-entrant and rotated re-entrant structure). The Low Cycle Fatigue (LCF) tests were performed at load control with the load ratio 0.1 in tensile. In the LCF tests, five loading levels were selected and at least two tests were performed at each loading level. The same loading conditions were then applied in the computational model in the framework of the ANSYS software package. For the fatigue life calculation, the strain life approach was used, based on the Coffin-Manson model with a Morrow mean stress correction. The comparison between computational and experimental results regarding Fa − N fatigue-life curves and observed fatigue failure path showed a reasonable agreement.

Mechanical Properties of Soil-Rock Mixture Filling in Fault Zone Based on Mesostructure

Soil-rock mixture (SRM) filling in fault zone is an inhomogeneous geomaterial, which is composed of soil and rock block. It controls the deformation and stability of the abutment and dam foundation, and threatens the long-term safety of high arch dams. To study the macroscopic and mesoscopic mechanical properties of SRM, the development of a viable mesoscopic numerical simulation method with a mesoscopic model generation technology, and a reasonable parametric model is crucially desired to overcome the limitations of experimental conditions, specimen dimensions, and experiment fund. To this end, this study presents a mesoscopic numerical method for simulating the mechanical behavior of SRM by proposing mesoscopic model generation technology based on its mesostructure features, and a rock parameter model considering size effect. The validity and rationality of the presented mesoscopic numerical method is experimentally verified by the triaxial compression tests with different rock block contents (RBC). The results indicate that the rock block can increase the strength of SRM, and it is proved that the random generation technique and the rock parameter model considering size effect are validated. Furthermore, there are multiple failure surfaces for inhomogeneous geomaterial of SRM, and the angle of the failure zone is no longer 45°. The yielding zones of the specimen are more likely to occur in thin sections of soil matrix isolated by blocks with the failure path avoiding the rock block. The proposed numerical method is effective to investigate the meso-damage mechanism of SRM.

Finite discrete-element modeling of multifracture propagation in fractured reservoirs

Abstract The topology of induced fractures by hydraulic fracturing is important for well performance in unconventional low-permeability reservoirs. Natural fractures are a common feature in geological formations and are preferred failure paths during hydraulic fracturing. Therefore, the interaction of hydraulic fractures and natural fractures is fundamental to the fracture growth in fractured reservoirs. Field observations of induced fracture systems show modeling fracture complexity to be needed for improving completion design and interpreting stimulated reservoir volume. In this study, a finite discrete-element model is presented to investigate multifracture propagation in fractured reservoirs. The numerical model captures the fracture complexity including branched, stranded, and kinked fractures, as well as offset crossing of natural fractures. The results show biased fracture growth in the fractured reservoir, which demonstrates the impacts of rock heterogeneity on multifracture propagation. This work also emphasizes the control of fluid partition at the wellbore and among the intersecting fractures. Fluid partition at the wellbore is found to be a major challenge to the completion design of tight cluster spacing, which has been shown to improve production in recent years.

Self-configuring BLE deep sleep network for fault tolerant WSN

This paper is focused on Wireless Sensor Network (WSN) leveraging on Bluetooth Low Energy (BLE) connectivity for low energy applications which is fault tolerant versus communication path failures. The topic is important to create a robust sensorized environment to be applied in industrial context or smart infrastructure to enable scheduled monitoring with low power consumption applications. Currently BLE applications are mainly thought for smart home solutions, health care and positioning systems. In those applications the BLE nodes are continuously supplied by external power suppliers. Our goal is to design a self-configuring network with a synchronized deep sleep behavior, aimed to optimize the energy consumption, with an overall active time interval constraint optimized with a data-driven method. The aim is to find a tradeoff between the on time and the ability to collect all the nodes data, pursuing a low power consumption. Our research is based on BLE protocols, interaction between edge systems for data collection and cloud system for data analysis and software agent optimization system. The paper analyses different configurations and describes the possible optimization algorithm to be used for the software agent design, in order to reach a fine-tuned control to improve the fault tolerance and fault diagnosis of the system. Finally experimental results are compared with the estimates obtained via a software simulation tool implemented for this architectural pattern.

Location Prediction for Improved Human Safety at Complex Environments

In underground operation, primary consideration is safety. In recent decades, for minimizing accident and for preventing major economic losses and casualties, wireless sensors are used by various large mineral countries through early warning. The Improved DV-Hop Localization Algorithm (IDVHLA) is used in existing works for doing this. However, accurate anchor node detection is impossible in existing works with the malicious nodes presence, where there won't be any accurate sharing of anchor node's location information. In case of emergency situation, faster communication is a highly complex one. A technique called Modified Distance Vector Hop based Multipath Routing Protocol (MDVHMRP) is introduced in this proposed research work for resolving this. In this work, to detect anchor node position, a Modified Distance Vector Hop technique is introduced. This research work considers time taken and session time for computing neighbour node's presence in addition to hop count values. Malicious nodes presence can be avoided by considering session time in neighbour node presence detection. The alert message are send by people in emergency crisis to sever in initial condition. Then Dynamic Source Routing (DSR) routing protocol is used for doing immediate route path selection. In case of route path failure, for ensuring uninterrupted communication and faster communication, this work introduces a multi path routing. The modified distance vector hop technique is used for predicting anchor node location information and predicted information will be transmitted. In NS2 simulation environment, overall evaluation of this research work is carried out. When compared with available techniques, localization accuracy is enhanced by proposed technique as proven in experimental results.

Multilayer Decision-Based Fuzzy Logic Model to Navigate Mobile Robot in Unknown Dynamic Environments

The investigation into mobile robot navigation under uncertain dynamic environments is of great significance. This paper seeks to solve the current problems which are the difficulty to plan in indeterminate ever-changing environments, the problem of optimality, failure in complex situations, and the problem of predicting the obstacle velocity vector. The objective of this study is to propose a multilayer decision-based fuzzy logic model to find the solution for robot navigation through a safe path while preventing any types of barriers and to understand the non-collision mobile robots’ movement in an unknown dynamic environment. In this study, the prediction and priority rules of a multilayer decision are used by the fuzzy logic controller to improve the quality of the next position with regard to its path length, safety, and runtime. The results of comparison studies revealed a considerable improvement in failure rate and path length. Outcomes show that the suggested method displays attractive features, for instance, great stability, great optimality, zero failure rates, and low running time. The average path length for all test environments is 13.11 with 0.47 a standard deviation that provides 89% of an average optimality rate. The average running time is about 5.31 s with a 0.25 standard deviation.

Beacon-Based Hybrid Routing Protocol for Large-Scale Unmanned Vehicle Ad Hoc Network

In this paper, we designed a beacon-based hybrid routing protocol to adapt to the new forms of intelligent warfare, accelerate the application of unmanned vehicles in the military field, and solve the problems such as high maintenance cost, path failure, and repeated routing pathfinding in large-scale unmanned vehicle network communications for new battlefields. This protocol used the periodic broadcast pulses initiated by the beacon nodes to provide synchronization and routing to the network and established a spanning tree through which the nodes communicated with each other. An NS3 platform was used to build a dynamic simulation environment of service data to evaluate the network performance. The results showed that when it was used in a range of 5 ~ 35 communication links, the beacon-based routing protocol’s PDR was approximately 10% higher than that of AODV routing protocol. At 5 ~ 50 communication links, the result was approximately 20% higher than the DSDV routing protocol. The routing load was not related to the number of nodes and communication link data and the protocol had better performance than traditional AODV and DSDV routing protocol, which reduced the cost of the routing protocol and effectively improved the stability and reliability of the network. The protocol we designed is more suitable for the scenarios of large-scale unmanned vehicle network communication in the future AI battlefield.

A Random-Field-Environment-Based Multidimensional Time-Dependent Resilience Modeling of Complex Systems

Over the past few decades, many research efforts have been dedicated to qualitatively and quantitatively evaluate resilience in different domains. As compared with research areas in social science and ecology, the concept of resilience in the engineering domain is relatively new. In the engineering domain, studies on resilience mostly focus on civil infrastructure. It is important to extend the concept of resilience to a broad range of engineering applications. The field environments of complex engineering systems vary with different applications. Even with the same component/system applied in different field environments, the ability, time, and resources required by failure detection, diagnosis, and restoration can be different. Hence, it is critical to introduce a new dimension, random field environment (RFE), into the development of the mathematical model for quantifying resilience. This article first introduces a new definition of resilience and then proposes a general RFE-based multidimensional time-dependent resilience model connecting reliability, vulnerability, and recoverability. Besides, we present a specific RFE-based multidimensional time-dependent resilience model by considering the specified functions of the impact of the RFE on system performance and recovery. Furthermore, we extend the proposed resilience model by incorporating multiple failure paths of complex systems. Finally, we apply the proposed resilience model to vehicular edge computing networks to evaluate the vehicular network resilience with the disruptive events on the communication links.

Routes to failure: Analysis of chemical accidents using the HFACS

Serious and similar chemical accidents frequently occur, which prompts continuous exploration of an effective way to prevent chemical accidents. The purpose of learning from accidents is to prevent the recurrence of similar incidents. An in-depth exploration of the causes is a prerequisite to ensure the effectiveness of learning from accidents. The interactions among causes can explain how a particular sequence of events results in an incident with unpleasant consequences. This research aimed to provide a more concrete and intuitive understanding of the interaction of causes and represent the routes to failure, showing how the chemical accidents happened. One hundred one chemical accidents were analyzed through the extended Human Factors Analysis and Classification System (HFACS) containing manifestations, and the associations between the high-frequency manifestations of adjacent levels were evaluated using Fisher's exact test. 21 groups of significant associations were identified, which clearly show how the manifestations at the upper level of the HFACS predict the adjacent lower level manifestations. A variety of potential failure paths for chemical accidents were presented, which need to be given more attention in developing future preventive measures. This work provides a new perspective and a theoretical basis for the prevention of chemical accidents.

An agent-based dynamic reliability modeling method for multistate systems considering fault propagation: A case study on subsea Christmas trees

The fault propagation of multistate systems (MSSs) with various operational modes is a critical factor affecting the reliability and safety of systems. However, traditional methods have difficulty describing the influence of function transitions and multiple faults of components on fault propagation, and are inapplicable for accurately evaluating the dynamic reliability of MSSs. To solve these issues, an agent-based method is developed to evaluate the dynamic reliability of MSSs. This study proposes a reliability modeling framework that consists of a management agent and several system agents. Combined with different agents, two types of models are established to describe the logical relationships among components. Moreover, Monte Carlo simulation is used to evaluate the dynamic reliability of MSSs, and a visual failure paths analysis method is proposed to inhibit potential risk. The LH4–1 horizontal Christmas tree is used to verify the effectiveness of proposed method. Under the designed working condition, the dynamic reliability curve of system with three operational modes and the visual failure paths including 15-node are obtained. By comparing the influence of failure rates, it is found that the production choke valve, flowlines, tree cap and MEG chemical control valve have a great impact on the system reliability.

A novel percolation model of leakage fluctuation behavior in gate-control dual-direction silicon controlled rectifier

Gate structures are used as efficient auxiliary components to improve the electrostatic discharge (ESD) performance of traditional silicon controlled rectifiers (SCRs). However, it has not been explored how the gate geometry potentially affects leakage behaviors and ESD characteristics of SCR devices. In this paper, a novel percolation model is proposed to address this problem. The percolation model fundamentally interprets the leakage fluctuation behavior of the gate-control dual-direction silicon controlled rectifier (GC-DDSCR) under ESD events. Two key parameters breakdown charge (QBD) and tunneling current (Jg) are simulated to link the gate geometry and gate oxide quality, revealing the principle of the leakage fluctuation behavior. The leakage fluctuation behavior may cause GC-DDSCR to work in an unstable state, leading to the premature functional failure of the intrinsic SCR path. Two GC-DDSCRs with different gate sizes are fabricated under a 0.5 μm CMOS technology and characterized by a transmission line pulse (TLP) test. Experiment results show the GC-DDSCR with a larger gate size is more prone to the leakage fluctuation behavior and the premature functional failure. The percolation model is qualitatively verified and the understanding of the gate structure in ESD devices is deepened.

System reliability of a gravity dam-foundation system using Bayesian networks

Traditionally, the reliability of a gravity dam-foundation system is evaluated using several typical dam sections. However, the performance of different dam sections may vary greatly even under the same environment and loading conditions due to the different dam structures and geological conditions. Therefore, an improved method was proposed in this study to assess the system reliability of a gravity dam-foundation system more reasonably. Based on the synchronous load increment in the whole dam and the response surface method (RSM), the critical failure modes were determined, and the RSM agent models for the strength failure and instability failure performance functions were constructed. Through the Monte Carlo simulation and the Bayesian progressive deduction, the method of system reliability was proposed. The application results of a gravity dam showed that the reliability in different dam sections was different for the same loading and environment conditions, and the system safety assessment was unreasonable using several typical dam sections. The proposed method overcame the defects of excessively searching the failure path, distorting the failure probability assessment, and incompletely describing the characteristics of the system using the traditional methods. It provides a new method for the system reliability evaluation of large-scale and complex structural systems.

Protection strategies of active defense in cyber-physical power systems

Cascading failure triggered by tiny failure iteratively propagates between physical power grid and communication network, causing severe damage on cyber-physical power systems. In this paper, we study the protection strategies of active defense to improve the robustness of systems. Based on analysis of cascading failure in systems, we classify failure into three types, structural failure, overload failure, and interdependent failure. Due to the severe damage caused by overload failure, we propose four protection strategies of active defense, through interdicting propagation path of cascading failure, to prevent overload failure. Compared with traditional redundancy protection and structure optimization, the protection strategies are economical and efficient, and can defend from an unknown attack. In simulation analysis, the protection strategies of active defense are proved to be effective in prevention of cascading failure.

Analytical evaluation of the effect of failure mechanisms on the bearing capacity factor Nγ for smooth strip footings

ABSTRACT This paper describes an analytical approach to investigating the role of failure mechanism in the bearing capacity of a smooth strip footing located on a -- soil. The approach combines the plane strain equilibrium condition and Mohr-Coulomb failure criterion to obtain the stress distribution along a translational, rotational and composite failure path. It is shown that the exact solutions for cohesion factor and surcharge factor for a -- soil do not require the superposition assumption and that both these factors are path-independent. A general closed-form path-dependent expression for the soil weight factor is also derived in terms of internal friction angle of the soil and the geometry of the failure path. The application of proposed expression on two-line and three-line failure modes as well as the well-known Hill mechanism are evaluated and discussed. Due to the overestimation of the soil weight factor by two-line and three-line modes, and by Hill mechanism, geometric modifications on the failure paths are proposed. The proposed mechanism and its bearing capacity are verified using the method of the stress characteristics. The effect of a non-associated flow rule on the reduction of the soil weight factor is also investigated quantitatively.

Application of hypergraph theory in the analysis of the failure propagation and diffusion behaviour of machining centre

AbstractTo improve the rationality of failure diagnosis, this research uses hypergraph theory as basis in proposing a method of analysing failure propagation behaviour to study the failure propagation mechanism from the system perspective. A hierarchical structure model is constructed by failure correlation analysis, matrix transformation and decomposition. The probability of failure is determined by considering the influence of multiple truncation data. On this basis, hypergraph theory is used to calculate the one‐step and cumulative coefficient of failure propagation and diffusion. The influence degree of failure is calculated by integrating the edge betweenness. Using the influence degree of failure as an indicator, failure propagation and diffusion behaviour are analysed, and critical failure nodes and paths are identified. Lastly, a machining centre is used as an example for specific application. The results are compared with the ranking results of critical failure propagation paths determined by other methods, and the effectiveness of the proposed method is verified.

POSIMNET-R: An immunologic resilient approach to position routers in Industrial Wireless Sensor Networks

Industry 4.0 has increased the interest in employing Industrial Wireless Sensor Network (IWSN) technologies in industrial automation. The advantages range from ease of installation and maintenance to reduced deployment time and infrastructure costs. However, industrial automation has critical requirements regarding network infrastructure, such as reliability and failure tolerance. Therefore, it is imperative to have an adequate placement of sensor and router nodes, to obtain a network with multiple paths, allowing the data to reach management systems within a reasonable time, even in the event of failures. The placement of router nodes has to consider latency, network lifespan, connectivity, and failure tolerance aspects in a possibly hostile environment, with classified areas and obstacles such as silos, tanks and buildings. We present a new approach, called POSIMNET-R, to place IWSN routing nodes in an industrial configuration, which circumvents forbidden areas and obstacles, based on Artificial Immunological Networks. The resulting network offers low failure rates and path redundancy criteria. The results have shown that POSIMNET-R was capable of providing a reliable network with multiple paths and resilience of the used routers equal to 81.50% in the basic case study and 73.66% in the real case scenario.

Improving Network Security Based on Trust-Aware Routing Protocols Using Long Short-Term Memory-Queuing Segment-Routing Algorithms

Defending all single connection failures for a particular system, segment routing issue, the switch will focus on the problems of selecting a small subset of trust-aware routing to improve the deep learning (DL). In the end, even if there were multiple path failures, these paths may introduce long-term, unnecessary overload in the proposed long short-term memory networks-based queuing routing segmentation (LSTM-QRS) experience of reducing traffic delays and adjusting traffic length by reducing network bandwidth. The critical factor is a novel traffic repair technique used to create a traffic repair path that switches to software-defined network (SDN) using multiple routing and providing additional flexibility in re-routing using long short-term memory networks (LSTM)-based queuing routing segment (LSTM-QRS) algorithms. It reduces the repair path length and recommends replacing the target-based traffic with the connection-based traffic fault detection router to avoid targeted traffic network congestion.