Failure Analysis Model Research Articles

A super element model for failure analysis of masonry buildings under lateral in-plane loading

This study developed a discrete element-based approach called Super Element Model to estimate the non-linear behavior and damage propagation of multi-story and multi-span masonry buildings subjected to in-plane lateral loads. To this aim, the piers and spandrels were substituted by a super element constituted by four large isosceles triangular panels and eight connector links, while the cross-joint areas remained rectangular. Two vertical/horizontal links also represent the connection of the super element of piers/spandrels to the cross-joint panels at each end. The large panels were assumed to behave elastically and inelasticity was only concentrated at the connector links. All the connector links were bi-component springs considering axial and shear behavior. With the help of masonry stress–strain curve, a simplified bi-linear behavior was extracted for springs. Thanks to the appropriate geometrical configuration of the piers’ equivalent super element, a dynamic interaction was provided between lateral capacity and normal stresses originating from lateral loads. After presenting a step-by-step algorithm for the model implementation in commercial software, two full-scale masonry buildings were chosen for validation purposes. The obtained results proved the proposed Super Element Model is reliable and user-friendly.

Smeared fixed crack model for quasi-static and dynamic biaxial flexural response analysis of aluminosilicate glass plates

Glass materials are extensively used in load-bearing structures and impact-resistant components because of their distinctive physical and chemical properties. Accurate predictions and assessment of the mechanical responses of glass structures are crucial for structural design and reliability analysis. In this study, quasi-static and dynamic ball-on-ring (BOR) biaxial flexural tests are conducted on aluminosilicate glass. The smeared fixed crack model is calibrated for deformation and failure analyses. First, the model parameters are calibrated carefully, particularly for different failure criteria. Both the deformation field and fracture modes agree well with the experimental observations during the quasi-static tests. For the low-velocity impact biaxial flexural loading condition, three different numerical techniques, namely the initial scaling tensile strength criterion, non-local approach with energy criterion, and rate-dependent failure stress criterion, are implemented in the numerical models for dynamic failure analysis. Finally, the proposed smeared fixed crack model is compared with the widely used Johnson Holmquist Ⅱ (JH-2) model and demonstrates advantages for low-velocity impact response analysis of glass structures.

A hybrid failure analysis model design for marine engineering systems: A case study on alternative propulsion system

Marine engineering systems have a fundamental role in ensuring the efficiency, safety, and sustainability of maritime transportation. The performance and reliability of these systems, particularly propulsion systems, are of paramount importance. This paper introduces a pioneering hybrid failure analysis model that integrate the Variable Weighted Synthesis Analytic Hierarchy Process (VWS-AHP) with the conventional Failure Mode and Effect Analysis (FMEA) methodology. The primary objective is to enhance the comprehension of failure modes within marine engineering systems, particularly focusing on alternative propulsion systems. While conventional FMEA is a widely employed methodology for analysis of failure modes, its capacity and effectiveness can be further augmented by integrating complementary techniques. The proposed hybrid model combines the robustness of FMEA in identifying failure modes with the VWS-AHP method’s ability to handle complex decision-making scenarios involving multiple criteria and varying levels of importance. This integration affords a comprehensive framework to assess failure risks, prioritize critical failure pathways, and evaluate the potential impacts of failures in marine engineering systems. To demonstrate the applicability of the proposed model, we conduct a case study on an alternative propulsion system. The outcomes of the case study showcase the efficacy of the hybrid model in enhancing FMEA.

Research on damage characteristics and contact interface evolution behavior of double-block ballastless track considering tunnel floor heave

Excessive railway tunnel floor heave (TFH) will reduce the durability of the track structure and jeopardize train operation safety. The TFH characteristics were fitted into cosine and bilinear curves according to the monitoring data. A nonlinear failure analysis model of double-block ballastless track under TFH was established. The deformation transfer law, structural damage mechanism and the interlayer bonding interface failure evolution of the track structure under different TFH characteristics were explored. The results show that the deformation of TFH can be well mapped to the track. The amplitude transfer ratio is less than 100 %. The maximum wavelength transfer ratio under the cosine and bilinear TFH is 129.3 % and 127.5 %, respectively. To avoid the damage of track structure, when the wavelength is 10 m, the amplitude of cosine and bilinear TFH should be controlled at 2.5 mm and 0.5 mm respectively. When the wavelength is greater than 10 m, the amplitude can be appropriately increased. To avoid interlayer bonding cracking, the cosine and bilinear amplitudes with a wavelength of 10 m should be controlled at 5 mm and 1.5 mm, respectively. The track-tunnel interlayer debonding failure under the cosine curve occurs at the edge of the TFH, while the bilinear curve occurs at the center and edge of the TFH. The gaps under the cosine and bilinear TFH exhibit double-peak and multi-peak shapes, respectively. This study can provide theoretical guidance for controlling the performance degradation of track structure caused by TFH.

Regularized Density-Driven Damage Mechanics Model for Failure Analysis of Cementitious Composites

Regularized Density-Driven Damage Mechanics Model for Failure Analysis of Cementitious Composites

A unified FFT framework with coupled gradient damage model and phase-field method for the failure analysis of composites

A unified FFT framework coupling the Gradient Damage Model (GDM) and the Variational Phase-Field Model (PFM) for failure analysis of composites is proposed. GDM and PFM are used to simulate the failure of the matrix and the interphase, respectively. Based on the similarity of the damage evolution equations (elliptic partial differential equations) of GDM and PFM, a unified iterative solution and numerical implementation based on fast Fourier transform (FFT) are derived, and simultaneously applied to a computational model. In addition, the high computational efficiency of the FFT method is used to solve the mechanical equilibrium problem. The complete form of the PFM is introduced to avoid erroneous damage diffusion at the different phase interfaces of the composites, and a stress decomposition-based PFM is formulated. 2D and 3D computational examples are established to investigate the mesh insensitivity of the damage models used and the erroneous damage diffusion at interfaces. The applicability of the stress decomposition-based PFM at interphase is discussed in the context of single-edge notched specimens under tension and fiber-reinforced composites with interfacial phases under transverse tension. Finally, the performance of the unified computational framework is evaluated using two simple numerical examples, and the mechanical behavior of unidirectional CF/PEEK composites under transverse tensile loading is simulated based on the unified framework. The results are compared with experiments to evaluate the computational accuracy and practical applicability of the proposed framework.

RISK ANALYSIS IN SANDWICH PANEL PRODUCTION WITH THE INTEGRATION OF FMEA AND FTA METHODS

General Background: Ensuring consistent product quality is crucial for maintaining competitive advantage, especially in manufacturing. PT. Starr Panel Industry, a company in the refrigeration sector, focuses on high-quality sandwich panels but experiences frequent defects in its production processes. Specific Background: Despite prioritizing premium raw materials, the company faces recurring product failures, particularly in the finishing phase, which affect production flow and on-time delivery. Knowledge Gap: Current quality assurance measures at PT. Starr Panel Industry lack a systematic approach to identifying and prioritizing the root causes of defects, hindering the development of targeted improvement strategies. Aims: This study aims to identify, analyze, and address potential failure modes and their root causes within the production processes, employing Failure Modes and Effects Analysis (FMEA) and Fault Tree Analysis (FTA). Results: The findings reveal that the finishing process has the highest Risk Priority Number (RPN) of 112, primarily due to insufficient adherence to standard operating procedures (SOPs) by the workforce. Novelty: The integration of FMEA and FTA provides a comprehensive failure analysis model, with FMEA ranking failure risks and FTA tracing them to foundational causes, offering a new dual-method approach to improve operational standards effectively. Implications: Implementing the proposed FMEA-FTA framework can significantly reduce product defects, improve quality consistency, and minimize delivery disruptions, especially in the critical finishing stage. Emphasizing SOP compliance across divisions, particularly in finishing, can lead to sustained quality improvements and enhanced operational efficiency in sandwich panel production.

Study on the lower head failure in severe accidents Part II: Thermal-mechanical coupling behavior analysis on CAP1400 reactor lower head

Under severe accident conditions with core meltdown, large amounts of molten material relocate to the lower head at high temperatures. Significant thermal and mechanical loads may lead to failure of the reactor pressure vessel (RPV) lower head, spreading radioactive fission products. Lower head failure time and location are crucial for accident mitigation and consequence assessment. This study developed a thermodynamic failure analysis model for the lower head by investigating material failure mechanisms, coupling this into an Integrated Severe Accident Analysis code (ISAA), and conducting experimental validation and applied research. Part I mainly introduces the thermodynamic analysis module development, validation against OLHF experiments, and preliminary failure criteria analysis. Results indicate the model accurately predicts lower head failure behavior, and Larson-Miller life fraction and Hedl-Dorn parameter criteria accurately assess lower head integrity. Part II presents applied research after validation and preliminary analysis. Using the improved ISAA, melt pool behavior and lower head thermal–mechanical response were analyzed for a CAP1400 small break loss-of-coolant accident (SBLOCA), assuming multiple safety system failures. Results indicate the bottom of the lower head melt pool didn’t form a hard shell due to high heat release rate, only an oxide shell layer around the second layer. Decay heat from melt pool components cannot be dissipated, leading to lower head failure. Further External Reactor Vessel Cooling (ERVC) heat transfer model analysis and research are needed in ISAA. The two developed mechanical analysis models predict material failure at high temperatures, and the timing and location of lower head failure are consistent, at approximately 16,000 s at 25.38°±5.47° on the lower head. The predicted failure mode is similar to Part I validation, indicating both Larson-Miller life fraction and Hedl-Dorn parameter criteria provide consistent lower head integrity judgments.

Mechanical failure analysis of drill string aggravated by stuck pipe after high-temperature melting-cutting operations

High-temperature melt cutting is an important technology for fast cutting and unjamming of downhole jammed tubular rods, but due to the well depth and mud environment, it cannot completely cut through the large wall thickness tubular rods such as weighted drill pipe, and it needs to be damaged by external load applied by drilling rig. The shape of the drill pipe kerf after the melt cutting operation is not the same, so the size of the applied external load needs to be further investigated. To address this problem, firstly, this paper establishes the Johnson-Cook ontology and failure model of S135 steel grade drilling tools based on the high temperature tensile test; secondly, according to the characteristics of the weighted drill pipe melt-cutting notch, a finite element model for mechanical damage failure analysis of weighted drill pipe with melt-cutting notch is established, and the reliability of the model is verified; lastly, the influence of high temperature and different notch characteristics (melt-cutting depth, circumferential cutting angle, Finally, the effects of high temperature and different notch characteristics (depth of cut, circumferential cutting angle, number of perforations) on the mechanical failure capacity of weighted drill pipe with fusion notch are analysed. The results show that the errors of the maximum stresses and strains of the samples obtained from the tensile fracture simulations at 20 °C and 400 °C and the maximum stresses and fracture strains obtained from the experiments are within 9 %, which verifies the accuracy of the model. Tensile loading was more effective than compressive loading in destroying the drill pipe; the change in loading speed had a small effect of 4.1 % on the tensile force required to destroy the drill pipe. The damage load of the drill pipe and the pressure acting on the cross-section of the fusion cut decreases with the increase of the fusion cutting depth; the damage load required decreases with the increase of the circumferential cutting angle and the number of openings, but the pressure acting on the cross-section of the fusion cut does not decrease. The softening effect of high temperature on the drill pipe is very obvious, and the tensile capacity of the drill pipe is attenuated by 80.6 % at a temperature of 800 °C. The research work can improve the operation process of cutting and unjamming thick-walled drilling tools in deep wells and guide the field operation to achieve the purpose of rapid unjamming.

Compressive failure analysis of composite honeycomb sandwich panels with impact damage and stepped-scarf repairs

Composite honeycomb sandwich panels (CHSPs) have been widely used in the aerospace industry owing to their lightweight and superior mechanical properties. However, these CHSPs are susceptible to impact damage, leading to a significant reduction in compressive strength and potentially jeopardize aircraft safety. It is crucial to investigate repair methods for CHSPs with impact damage. This paper aims to evaluate the repair performance of CHSPs with impact damage through an analysis of their compressive failure behaviors. To accomplish this, both experimental tests and advanced numerical models are employed. The numerical models for the intact, damaged and stepped-scarf repaired CHSPs are established using the progressive failure analysis model, cohesive zone model and sandwich plate theory. A good agreement is observed between the experimental results and numerical predictions of compressive failure behaviors. Moreover, the validated numerical models are successfully utilized for determining optimum repair parameters by parametric analysis of the repaired CHSPs. The establishment of these numerical models offers an accurate and cost-effective evaluation of repair performance for CHSPs with impact damage, highlighting the novelty and main contribution of this paper.

Experimental and numerical studies on compressive failure behaviors of stepped-scarf repaired composite stiffened panels

Composite materials have been widely used in aerospace and other fields due to their superior mechanical properties. The repair of composite structures has received increasing attention in recent decades. In this work, the compressive failure behaviors of intact, defective and stepped-scarf repaired composite stiffened panels are analyzed experimentally and numerically. The evaluation of repair schemes of composite stiffened panels based on finite element (FE) analysis is investigated by comparison with experimental results. The maximum absolute value of error in load-carrying capacity between the numerical and experimental results does not exceed 3.65%. Progressive failure analysis model and cohesive zone model are utilized to reveal the damage evolution of multilayered composites and adhesive film. The failure modes obtained from FE analysis are in good agreement with the experimental observations. Moreover, the influence of the stepped-scarf ratio and repair patch angle deviation on the compressive strength is investigated to determine optimum repair parameters based on the established FE models. On the basis of the conducted studies, the results provide valuable insights into the evaluation and validation of repair schemes for composite stiffened panels with high accuracy and cost-effectiveness.

A Prescriptive Model for Failure Analysis in Ship Machinery Monitoring Using Generative Adversarial Networks

In recent years, advanced methods and smart solutions have been investigated for the safe, secure, and environmentally friendly operation of ships. Since data acquisition capabilities have improved, data processing has become of great importance for ship operators. In this study, we introduce a novel approach to ship machinery monitoring, employing generative adversarial networks (GANs) augmented with failure mode and effect analysis (FMEA), to address a spectrum of failure modes in diesel generators. GANs are emerging unsupervised deep learning models known for their ability to generate realistic samples that are used to amplify a number of failures within training datasets. Our model specifically targets critical failure modes, such as mechanical wear and tear on turbochargers and fuel injection system failures, which can have environmental effects, providing a comprehensive framework for anomaly detection. By integrating FMEA into our GAN model, we do not stop at detecting these failures; we also enable timely interventions and improvements in operational efficiency in the maritime industry. This methodology not only boosts the reliability of diesel generators, but also sets a precedent for prescriptive maintenance approaches in the maritime industry. The model was demonstrated with real-time data, including 33 features, gathered from a diesel generator installed on a 310,000 DWT oil tanker. The developed algorithm provides high-accuracy results, achieving 83.13% accuracy. The final model demonstrates a precision score of 36.91%, a recall score of 83.47%, and an F1 score of 51.18%. The model strikes a balance between precision and recall in order to eliminate operational drift and enables potential early action in identified positive cases. This study contributes to managing operational excellence in tanker ship fleets. Furthermore, this study could be expanded to enhance the current functionalities of engine health management software products.

A novel FFT framework with coupled non-local elastic-plastic damage model for the thermomechanical failure analysis of UD-CF/PEEK composites

A novel FFT-based computational framework for coupling non-local elastic-plastic damage model is proposed in this paper, which is employed to accurately simulate the transverse tensile behaviors of unidirectional (UD) CF/PEEK composite materials under different temperatures. To address the distinct material properties exhibited by different microscopic constituents within the composite, two approaches are employed: (i) an integral-type regularized traction-separation damage model is applied to the interphase debonding, and (ii) an implicit gradient regularization technique for Lemaitre-type damage (matrix cracking) of the PEEK. By coupling the non-local damage model capable of accurately characterizing different failure modes within composites with an FFT computational framework, accurate predictions of the transverse tensile performance of UD-CF/PEEK composites at different temperature conditions can be achieved. Furthermore, the influence of non-local feature parameters and interphase mechanical properties on the composite's mechanical behavior is thoroughly discussed. Comparisons with experimental results affirm the accurate prediction of the transverse tensile behavior of UD-CF/PEEK composites through the proposed computational framework. Ultimately, based on this framework, the transverse tensile modulus and strength of UD-CF/PEEK composites, considering different fiber volume fractions and temperatures, are predicted, successfully demonstrating the effectiveness and applicability of the proposed approach in forecasting the mechanical behavior of composites.

Myrmecia: Failure analysis and thermodynamic coupled simulation program for heat pipe in micro reactor based on MOOSE

The heat pipe cooled microreactor (HPMR) has become increasingly popular in the realm of research, largely due to its clean, efficient, and safe properties. This paper presents the development of Myrmecia, a simulation software built on the MOOSE framework. Myrmecia integrates the thermodynamic model and failure analysis model of a heat pipe, facilitating the assessment of the failure probability of a given heat pipe based on its thermodynamic parameters and design parameters. The verification of both models has been conducted. The findings demonstrate that increasing the wall thickness of the heat pipe leads to a reduction in its heat transfer capacity, while significantly decreasing the failure probability. Furthermore, appropriately elevating the initial temperature contributes to a decreased likelihood of a break event occurring in the heat pipe. Under the assumption of a fixed heat source/sink temperature, enlarging the inner diameter of the heat pipe exerts negligible influence on the failure probability, yet substantially enhances its heat transfer capability. In summary, various parameters of the heat pipe exert considerable influence on both its safety performance and heat transfer performance. Consequently, the trade-off between these two aspects represents a critical consideration for heat pipe designers.

Sub-Homogeneous Peridynamic Model for Fracture and Failure Analysis of Roadway Surrounding Rock

Sub-Homogeneous Peridynamic Model for Fracture and Failure Analysis of Roadway Surrounding Rock

Failure modes-based seismic fragility analysis of concrete gravity dams considering concrete heterogeneity

The heterogeneity of mass concrete often leads to the initiation of micro-cracks in gravity dams, while the accumulation of damage of concrete on the meso-scale leads to the cracking behaviour on the macro-scale. To improve the seismic safety of the dam, a comprehensive study on the effect of heterogeneous properties is crucial in seismic fragility analysis. A novel methodology considering concrete heterogeneity for seismic fragility analysis was developed by combining damage element model for seismic failure analysis, a five-level standard for failure modes-based seismic damage state and a method to generate seismic fragility curves. Then, seismic failure analysis of the Koyna gravity dam was taken as an example to verify the correctness of the damage element model, the damage process of dam from micro-cracks to macro-cracks were simulated. Finally, the seismic fragility of a practical dam in China was studied to verify the effectiveness of the proposed methodology. The results showed that simulated failure modes-based fragility curves were suitable for the target dam and more capable of considering the uncertainty of concrete material parameters. The obtained fragility curve proved valuable in optimizing seismic design, reinforcement and maintenance measures and improve seismic capability of the dam.

An improved peridynamic model for failure analysis of composite laminates

The study presents an improved peridynamic (PD) model for predicting the failure mode of composite laminates without any limitation to fiber orientation. In order to describe the directional dependency of composite laminae, the structural rotation angle is introduced into the PD framework to overcome the flaw that the fiber orientation is a specific value in conventional PD models. In improved PD model (IPM), two types of material points are used to model laminated structures, and a new force function mapping relationship is derived to achieve stable load transfer between in-plane and interlayer material points. As a result, the discrete grid of in-plane material points do not have to coincide with interlayer material points, and the technical difficulties in modeling multilayer laminates with general layups can be addressed. Since the IPM matches the microscopic configuration of practical composite structures, these damage characteristics, such as the damage path, crack initiation point, etc., correlate well with the experimental results. The numerical accuracy of the developed PD model are verified by simulating a series of examples of composite laminae with different fiber orientations, and the damage example further demonstrates the strong capability of the IPM in capturing failure modes of laminates with general layup.

A finite element-convolutional neural network model (FE-CNN) for stress field analysis around arbitrary inclusions

This study presents a data-driven finite element-machine learning surrogate model for predicting the end-to-end full-field stress distribution and stress concentration around an arbitrary-shaped inclusion. This is important because the model’s capacity to handle large datasets, consider variations in size and shape, and accurately replicate stress fields makes it a valuable tool for studying how inclusion characteristics affect material performance. An automatized dataset generation method using finite element simulation is proposed, validated, and used for attaining a dataset with one thousand inclusion shapes motivated by experimental observations and their corresponding spatially-varying stress distributions. A U-Net-based convolutional neural network (CNN) is trained using the dataset, and its performance is evaluated through quantitative and qualitative comparisons. The dataset, consisting of these stress data arrays, is directly fed into the CNN model for training and evaluation. This approach bypasses the need for converting the stress data into image format, allowing for a more direct and efficient input representation for the CNN. The model was evaluated through a series of sensitivity analyses, focusing on the impact of dataset size and model resolution on accuracy and performance. The results demonstrated that increasing the dataset size significantly improved the model’s prediction accuracy, as indicated by the correlation values. Additionally, the investigation into the effect of model resolution revealed that higher resolutions led to better stress field predictions and reduced error. Overall, the surrogate model proved effective in accurately predicting the effective stress concentration in inclusions, showcasing its potential in practical applications requiring stress analysis such as structural engineering, material design, failure analysis, and multi-scale modeling.

Thermal-fluid-structure coupling progressive failure analysis for the type III composite cylinder under localized fire

Predicting the failure characteristics of composite cylinders under fire is the key to improve the fire resistance and safety of cylinders. However, the current thermal-mechanical coupled failure analysis methods for composite cylinders under fire have several limitations such as oversimplification of the cylinder dome's geometric model and the fire source. To solve these problems, a comprehensive three-dimensional thermal-fluid-structure coupling progressive failure analysis method is developed. This method encompasses a fully coupled conjugate heat transfer model, a FLUENT-ABAQUS data transfer method, and a progressive failure analysis model integrates the Hashin failure criterion and nonlinear damage evolution for fiber reinforced composites. The method is adopted to analyze the fire-resistant performance of a type Ⅲ cylinder to obtain the fire-resistant time, failure pressure and burst location of the cylinder, finding that the pattern of failure pressure depreciation correlates with the burst location of cylinder under localized fire. Besides, the influence of the glass-fiber/epoxy layer on the fire-resistant performance of the cylinder is discussed, demonstrating that even a thin layer of glass-fiber epoxy can significantly increase the fire resistance time of the cylinder.

Failure analysis and flow dynamic modeling using a new slow-flow functionality: the 2022 Jiaokou (China) tailings dam breach

Failure analysis and flow dynamic modeling using a new slow-flow functionality: the 2022 Jiaokou (China) tailings dam breach