Reliable Design Research Articles

Prediction of BLEVE-induced response of road tunnel using Transformer network with modified self-attention (SAMT)

Road tunnels might be exposed to Boiling Liquid Expansion Vapor Explosion (BLEVE) due to the transportation of liquified gas tankers passing through road tunnels. An efficient and accurate prediction of the response of road tunnels under internal BLEVEs can facilitate the reliable BLEVE-resistant design and risk assessment of road tunnels. This study introduces an advanced deep-learning model that employs a Transformer-based architecture with a modified self-attention mechanism, termed as Self-Attention Modified Transformer (SAMT), to predict BLEVE-induced support rotation of tunnel structure, which is a common criterion in assessing reinforced concrete structure damage to blast loads. Unlike the Transformer with the traditional self-attention mechanism, the proposed SAMT effectively aggregates global information across all variables while mitigating undue dependencies among uncorrelated variables. Consequently, the proposed SAMT is better suited for processing tabular data with uncorrelated variables. The feasibility and advantages of the proposed SAMT are verified by extensive data generated using calibrated numerical models of box-shaped road tunnels subjected to internal BLEVEs. By comparing the performance of the proposed SAMT with the non-modified Transformer network (FT-Transformer) as well as two other typical deep learning networks, i.e., Multi-layer Perceptron (MLP) and Residual Network (ResNet), it is found that the SAMT offers higher prediction accuracy and robustness than the other three models in predicting BLEVE-induced support rotations of box-shaped road tunnels. The study demonstrates that the proposed SAMT is an effective tool for the prediction of BLEVE-induced support rotations of road tunnels.

Bending behavior of detachable tapered-head bolt inter-module connection of steel modular structure

The force transmission between steel module units is primarily achieved through inter-module unit connections. However, the existing connections often fail to meet the installation requirements for central connections, and some connections require on-site welding and are difficult to disassemble, with strict demands on the cross-section of beams and columns. To address the shortcomings of the current connections, a detachable tapered-head bolt inter-module connection of steel modular structure is proposed. It solves the problem of limited installation space for central connections, enabling rapid installation and disassembly with high construction efficiency. A study on the bending behavior of the connection under static load is conducted through four-point bending tests. Various mechanical characteristics, including failure mode, ductility, load-bearing capacity, and strain distribution are investigated. The results indicate that the primary failure mode for the connection under bending moment is the yielding of the bottom plate of the upper corner part, demonstrating a ductile failure mode. The results of parametric numerical simulations show that increasing the bottom plate thickness and side plate thickness of the upper corner part are effective measures to improve the connection bending performance. Furthermore, the simplified theoretical calculation model for the connection is established, and the formula for calculating the bending bearing capacity is proposed. This provide a reliable design basis and reference for the practical application of the connection in engineering projects.

Influence of process variations on clinch joint characteristics considering the effect of the nominal tool design

Focusing on upcoming challenges in lightweight design, such as increasing emission targets or novel multimaterial connections, versatile applicable and environmentally friendly production technologies are crucial. In this context, mechanical joining technology clinching offers a fast and energy-efficient procedure for assembling sheet metals, being a proper alternative to established joining methods, such as spot welding. However, the design of clinch points is a challenge, which is partly supported by numerical or data-based approaches for optimal tool dimensions assuring proper joint characteristics. While this is usually done for an ideal environment, real joining processes are characterized by multiple inevitably varying parameters, e.g. of the material, which have a significant impact on the quality of clinch points. Therefore, this contribution addresses the current gap by analyzing the effect of parameter variations or uncertainties on the resulting joint characteristics and studying the impact of the nominal tool design. Thus, an efficient meta-model-based variation simulation procedure is proposed and used for analyzing the effect of different tool design configurations and variation scenarios. Based on the results, it was found that varying process parameters have a strong impact on the resulting joint characteristics, whereby the effect significantly depends on the nominal tool design. This reveals the potential for a robust tool design and implies that the nominal tool design and the tolerancing of parameters should be done simultaneously for a reliable virtual joining point design without extensive iterations and physical tests.

Multi-XGB: A multi-objective reliability evaluation approach for aeroengine turbine discs

Multiple failure sites often co-existed in aeroengine turbine discs, its reliability performance contains complex characteristics of high-nonlinearity and multiple-output, leading to the insufficient reliability evaluating accuracy/efficiency of traditional direct simulation or surrogate separate methods. To address this problem, a multi-XGB model is presented by fusing the linkage sampling technique to extract a multi-input multi-output dataset, the XGBoost series ensemble platform to build the modelling architecture, and the Bayesian optimization algorithm to find the optimal model hyperparameters. Moreover, a multi-XGB driven multi-objective reliability evaluation framework is presented as well. Regarding a typical aeroengine high-pressure turbine disc with multiple failure sites (i.e., disc core, disc rim) as an example, the probabilistic distributions, correlation relationships, and reliability degree for each/all frail sites in turbine disc are acquired by applying the presented multi-XGB model. Through the method comparisons, the presented method is verified to hold high computing accuracy and efficiency in evaluating the multi-objective reliability of turbine discs. The current efforts shed light on the theoretical development for reliability evaluation, design, and optimization of high-end equipment like aeroengine.

Highly deformable bi-continuous conducting polymer hydrogels for electrochemical energy storage

Conducting polymer hydrogels with inherent flexibility, ionic conductivity and environment friendliness are promising materials in the fields of energy storage. However, a trade-off between mechanical and electrochemical properties has limited the development of flexible/stretchable conducting polymer hydrogel electrodes, owing to the intrinsic conflict among mechanical and electrical phases. Here, we report a reliable design to enable conducting polymer with both exceptional mechanical and electrical/electrochemical performance through the construction of bi-continuous conducting polymer crosslinked network. The resultant bi-continuous conducting polymer hydrogels (BCPH) demonstrate significantly improved mechanical and electrochemical properties compared to the conventional conducting polymer hydrogel (CPH) electrode. BCPH presents a high specific capacitance of 715 F g−1 at 0.5 A/g, a high mechanical strength (∼1 MPa) and a large stretchability (∼300%). Enabled by such intrinsically deformability and electrochemical properties, we further demonstrate its utility in flexible solid-state supercapacitor (FSSC), which exhibits an outstanding specific capacitance of 760 mF cm−2 at 2 mA cm−2, excellent electrochemical stability with 81% capacitance retention after 5000 charge/discharge cycles, and superior bending cycle stability. This simple and scalable strategy provides a platform for the fabrication of high-performance conducting hydrogel electrodes for various wearable electronic equipment.

Failure behavior of tantalum electrolytic capacitors under extreme dynamic impact: Mechanical–electrical model and microscale characterization

Tantalum electrolytic capacitors have performance advantages of long life, high temperature stability, and high energy storage capacity and are essential micro-energy storage devices in many pieces of military mechatronic equipment, including penetration weapons. The latter are high-value ammunition used to strike strategic targets, and precision in their blast point is ensured through the use of penetration fuzes as control systems. However, the extreme dynamic impact that occurs during penetration causes a surge in the leakage current of tantalum capacitors, resulting in a loss of ignition energy, which can lead to ammunition half-burst or even sometimes misfire. To address the urgent need for a reliable design of tantalum capacitor for penetration fuzes, in this study, the maximum acceptable leakage current of a tantalum capacitor during impact is calculated, and two different types of tantalum capacitors are tested using a machete hammer. It is found that the leakage current of tantalum capacitors increases sharply under extreme impact, causing functional failure. Considering the piezoresistive effect of the tantalum capacitor dielectric and the changes in the contact area between the dielectric and the negative electrode under pressure, a force–electric simulation model at the microscale is established in COMSOL software. The simulation results align favorably with the experimental results, and it is anticipated that the leakage current of a tantalum capacitor will experience exponential growth with increasing pressure, ultimately culminating in complete failure according to this model. Finally, the morphological changes in tantalum capacitor sintered cells both without pressure and under pressure are characterized by electron microscopy. Broken particles of Ta–Ta2O5 sintered molecular clusters are observed under pressure, together with cracks in the MnO2 negative base, proving that large stresses and strains are generated at the micrometer scale.

Establishment and Analysis of Load Spectrum for Bogie Frame of High-Speed Train at 400 km/h Speed Level

The bogie frame, as one of the most critical load-bearing structures of the Electric Multiple Unit (EMU), is responsible for bearing and transmitting various loads from the car body, wheelsets, and its own installation components. With the increasing operating speed of high-speed EMUs, especially when the design and operational speeds exceed 400 km/h, the applicability of current international standards is uncertain. The load spectrum serves as the foundation for structural reliability design and fatigue evaluation. In this paper, the measured loads of the bogie frame of a CR400AF high-speed train on the Beijing–Shanghai high-speed railway are obtained, and the time-domain characteristic of the measured loads is analyzed under different operating conditions. Then, through the Weibull distribution of three parameters, the Weibull parameters at the 450 km/h speed level are fitted, and the maximum load and cumulative frequency under the speed level are derived. Finally, the load spectrum of the bogie frame at the 450 km/h speed level is established, which provides a more realistic load condition for accurately evaluating the fatigue strength of bogie frames at higher speed levels.

Optimizing MEP Design in Pharmaceutical Cleanroom with the Integration of 2D To 7D in BIM

Abstract: This paper examines the optimization of pharmaceutical cleanroom design using 2D to 7D Modelling in Building Information Modelling (BIM). The goal is to enhance the reliability, different methods, statistical data, and performance of pharmaceutical production plants by effectively allocating components within design constraints. Mathematical optimization techniques improve facility design, ensuring robustness and operational efficiency. The study proposes a reliable optimal design for air-conditioning systems in pharmaceutical cleanrooms, considering uncertainties in design parameters and operational strategies. Resilient cleanroom systems are developed, and adaptable to various conditions while maintaining high performance standards. Additionally, the research explores the application of experimental design methodologies in optimizing drug delivery systems, such as factorial and etc, to enhance the quality and efficiency of pharmaceutical products and processes.

The effect of rail crown film hole injection angle and blowing ratio on the flow and cooling performance of the squealer tip in a turbine blade

Squealer tip is considered as an efficient and reliable tip geometry design in leakage loss control and thermal load reduction in heavy-duty gas turbine blade. The cooling and aerodynamic characteristics of a squealer tip with different film hole parameters are investigated after validating the numerical approach. Firstly, superior aerodynamic and cooling performance of the rail crown film hole (RCFH) scheme is proved by comparing three squealer tip structures. Subsequently, two kinds of injection angles (streamwise injection α and normal injection β) and three angle values (35°, 90°, and 145°) are studied in RCFH schemes. Finally, a compound angle scheme consisting of optimal α and β is investigated at blowing ratios (M) varying from 0.5 to 2.0. In varied α hole schemes, the velocity of the coolant can be divided into the radial and streamwise components, the effects of which on leakage control are complementary, leading to minimal sensitivity of total leakage flow rate (LFR) to α. Increasing and decreasing α can both enhance the coolant attachment on the rail crown surface compared with the radial injected scheme. In varied β hole schemes, more coolant momentum is used to resist the leakage flow as β increases, which results in remarkable LFR reduction. Moreover, the back-press effect of leakage flow on the coolant is markedly enhanced, improving the utilization of coolant. In compound angle scheme, increasing M leads to enhanced impingement on clearance flow, and the maximum values of average film cooling efficiency (η) on the rail crown and cavity floor appear at M = 1.0 and M = 1.5, respectively.

Coupling field optimization to improve the thermal transport of Gr/h-BN heterostructure

We perform a numerical evaluation on the multi-physical field coupling effect to improve the interfacial thermal conductivity (ITC) of Gr/h-BN (Graphene/Hexagonal boron nitride) planar heterostructure. The model of Gr/h-BN planar heterostructure (C-BN bonded configuration) is built to investigate the effect of the multifactor coupling effect of different temperatures, N-doping concentration, and single vacancy concentration on the ITC. Finally, the Box-Behnken orthogonal model is established to determine the optimal value of ITC under the coupling effect of multi-physical fields by response surface analysis, and the optimal value of ITC is 14.456 GW m−2 K−1 when the temperature is 673 K, the single vacancy is 2.57 %, and the N-doping is 18.9 %. It implies that the proper coupling configuration is found effective in improving the interfacial thermal conductivity of the Gr/h-BN heterostructure. This work is hoped to help promote the thermal reliability design of graphene heterogeneous interface for related micro/nano semiconductor devices.

Fatigue-resistant adhesion through high energy barriers

The applications of soft materials in various fields often require interfacial adhesion to sustain prolonged static or cyclic loads, whereas most existing adhesives are susceptible to fatigue failure. Unlike in a quasistatic debonding process, which depends more on the average resistance, the key to preventing fatigue crack propagation is to build up high energy barriers locally. Herein, we invoke three types of structural designs to induce large energy barriers at the interface to achieve fatigue-resistant adhesion. By varying the local bending stiffness of the backing layer, locally altering the fracture mode through kirigami patterns, or hindering crack initiation with simple edge notches, we enhanced the fatigue thresholds of various adhesives against peeling by several orders of magnitude, reaching record-breaking values. To verify the proposed mechanism and reveal the details of these remarkable enhancements, we develop theoretical models to study the peeling processes. Based entirely on structural design, the proposed mechanism is non-material-specific and universally applicable to various intermolecular interactions under any harsh environment, such as high temperature, high humidity, and physiological environments. We envision that the strategy and methodologies presented can pave the avenue of future adhesion designs for both durability and reliability.

Dynamic Sensor Selection for Efficient Monitoring of Coupled Multidisciplinary Systems

Abstract Coupled multidisciplinary systems involve different disciplines/subsystems with feedback-coupled interactions, illustrating the complex interdependencies inherent in real-world engineering systems. Effective monitoring of a coupled multidisciplinary system is crucial for real-time assessment of the interactions between various disciplines within the system. This monitoring provides the data necessary for detecting and addressing issues in a timely manner and facilitates adaptive decision-making for taking reliable design or control actions. However, processing and analyzing data in real time is computationally intensive, and limited resources, such as computational power, sensor capabilities, and budget, may constrain the extent to which a system can be monitored comprehensively. To address this, this paper develops a particle-based approach that dynamically selects a subset of sensors that provides the highest information about the state of the system in real time. The proposed approach first predicts the amount of uncertainty in the estimation of the state of the system given noisy measurements from different subsets of available sensors. Then, it selects the sensors that reduce this uncertainty the most, enhancing the precision and efficiency of the monitoring process. The efficacy of the proposed framework is demonstrated via two coupled multidisciplinary systems in the numerical experiments.

Design of government agency’s performance accountability system best practice implementation: Indonesia experience

Research aims: This study aims to explain the performance accountability system best practice implementation of Yogyakarta Special Region’s (Yogyakarta) Local Government through a valid and reliable design that is ready to be adopted and used as a role model by other local governments.Design/Methodology/Approach: This research used a qualitative method with a case study approach to reach the research objective. Research data was collected using in-depth interviews and documentation techniques.Research findings: This study succeeds in realizing a design by providing an applicable template as a recommendation tool compiled from seventeen items of success measures that are the performance accountability system’s best practices at the Yogyakarta Local Government. This study becomes more complex because it has been equipped with simulations of template filling out as well as a comparative analysis of the performance accountability system’s implementation between the Yogyakarta Local Government and the Central Java Local Government. The results of filling out the template for the Central Java Local Government revealed that 88% of the success measures have been applied, and another 12% have not.Theoretical contribution/Originality: This study provides an academic contribution as a reference related to the performance accountability system of government agencies.Practitioner/Policy implication: This study also provides a practical contribution to other local governments regarding the application of the performance accountability system’s best practices at the Yogyakarta Local Government through the design of the performance accountability system’s best practices that can be adopted and used as a role model in strengthening the performance accountability system.Research limitation/Implication: This study has limitations, namely that the researcher was unable to conduct interviews with the Ministry of Administrative and Bureaucratic Reform due to communication problems, which prevented the interview process from being carried out.

QCA-based fault-tolerant XOR Gate for reliable computing with high thermal stability

The XOR gate is an essential element in the design of digital circuits due to its versatility and usefulness. The design of XOR gate in this paper is based on Quantum-dot Cellular Automata (QCA) 2D planner technology with no line-to-line intersections. The output amplitude is improved by redundant cell-based design, which also helped reliability and fault tolerance outperform. The proposed XOR gate achieves fault tolerance to single-cell addition and missing-cell defects from 68.48% to 95.33%. In addition, the proposed XOR gate is also fault-tolerant against multiple-cell missing defects, as verified from the simulations. Furthermore, high thermal stability makes the circuit reliable for QCA-based digital design applications. The digital design applications such as 4-bit B2G code converter and a 4-bit parity checker are designed from this XOR gate, utilizing 438 and 414 cells, respectively. This demonstrates its effectiveness in designing fault resilient and reliable circuit designs for various applications.

Analysis of mechanical response and failure characteristics of tunnels crossing active faults considering axial force and geometrical nonlinearity

Tunnels subjected to active fault dislocation may experience significant damage. This paper establishes a novel methodology and solution procedure for analyzing the mechanical response and failure characteristics of tunnels subjected to active fault dislocation based on an elastic foundation beam model. The proposed methodology includes axial, transverse, and vertical soil-tunnel interaction terms, in addition to geometrical nonlinearity and axial force terms in the governing equation. This approach has a significantly extended application range, effectively addressing the problems encountered in tunnels crossing active faults with diverse crossing angles, dip angles, and fault types. The proposed methodology is verified by comparison to a 3D FEM model with various fault types, experimental tests, and on-site case, and the results are in excellent quantitative and qualitative agreement with the numerical, experimental, and on-site results. When fault displacement is below 0.5 m, disregarding geometric nonlinearity results in calculation errors of approximately 10% to 17% for peak axial force (Nmax), 18% to 22% for peak shear force (Vmax), and 20% to 30% for peak bending moment (Mmax). Finally, the responses caused by different factors, i.e., fault type, fault displacement, tunnel stiffness, and tunnel diameter, are investigated in detail to better understand tunnels crossing active faults. The results show that amongst the various fault types, the Vmax and the Mmax experienced by tunnels subjected to oblique slip-fault dislocation surpass those of other fault types, accompanied by the most extensive failure range. The augmentation of fault displacement, tunnel stiffness, and tunnel diameter precipitates a corresponding escalation in the Nmax, Vmax, Mmax, and failure range. Under oblique-slip fault dislocation, the tunnel undergoes an initial phase of shear failure, followed by tension-bending failure, delineated by distinct fault displacement thresholds of 0.1 m and 0.2 m, respectively. The proposed methodology provides the advantage of reliable stability analysis and design of tunnels crossing active faults.

A stochastic modelling framework for predicting flexural properties of ultra-thin randomly oriented strands

A stochastic modelling framework is developed to predict the flexural properties of high-strength sheet moulding compounds made of randomly oriented ultra-thin carbon fibre-reinforced thermoplastic prepreg tapes. The model enables reliable designs using ultra-thin randomly oriented strands with less testing, leading to potential applications in automotive primary structures. The stochastic model is based on a Monte Carlo simulation. The flexural modulus is predicted using classical laminate theory, while the flexural strength is predicted by following a Weibull distribution. Fibre discontinuities are considered through stress concentrations introduced by tape overlaps. The results are validated against new 3-point bending and previously reported 4-point bending experimental results. A scaling effect on strength and scatter is predicted, and its implications for structural applications are also discussed.

Novel study on active reliable PID controller design based on probability density evolution method and interval-oriented sequential optimization strategy

Vibration active control is a significant problem in practical engineering, but the influence of hybrid uncertainties in practical engineering cannot be ignored. For the uncertainties with adequate data, probability theory can be used while for the uncertainties with insufficient data, probability theory is limited and interval quantification can be used. Taking the widely used proportional-integral-differential (PID) control as an example, a novel study on controller design based on probability density evolution method and interval-oriented sequential optimization strategy considering interval and random uncertainties is proposed. Firstly, under a certain sample point of interval uncertainties, probability density evolution equation is utilized to calculate the probability density function of uncertain response considering only random uncertainties. In this way the probabilistic reliability corresponding to the sample point can be obtained. Then the hybrid reliability is defined as the average probability within the interval uncertainty and the adaptive dichotomy method is utilized to choose proper sample points of interval uncertainties, in which the reliability curve and the interval uncertainty axis is regarded as the judgement of convergence. Next the hybrid reliability is introduced to the optimization as a constraint and the PID gains reliable design optimization is established to balance the energy-consuming and safety. Finally, the sequential optimization strategy is adopted to improve the efficiency of optimization. In every iteration step of the optimization, the constraint of deterministic optimal design is adjusted according to the static reliability at the moment before the passage or reaching the maximum value. Three numerical examples are presented to demonstrate the accuracy and practicability of the proposed framework.

A graphical comparison of screening designs using support recovery probabilities

A screening experiment attempts to identify a subset of important effects using a relatively small number of experimental runs. Given the limited run size and a large number of possible effects, penalized regression is a popular tool used to analyze screening designs. In particular, an automated implementation of the Gauss-Dantzig selector has been widely recommended to compare screening design construction methods. Here, we illustrate potential reproducibility issues that arise when comparing two-level screening designs via simulation, and recommend a graphical method, based on screening probabilities, which compares designs by evaluating them along the penalized regression solution path. This method can be implemented using simulation, or, in the case of lasso, by using exact local lasso sign recovery probabilities. Our approach circumvents the need to specify tuning parameters associated with regularization methods, leading to more reliable design comparisons. This article contains Supplementary Materials including code to implement the proposed methods.

Probabilistic LCF life prediction framework for turbine discs considering random load history

Probabilistic LCF life prediction framework for turbine discs considering random load history

Proposal and evaluation of new models for predicting the FRP contribution to shear strength in reinforced concrete beams using gene expression programming

Fiber-reinforced polymers (FRP) have been widely used in shear strengthening applications of reinforced concrete (RC) beams. The accurate prediction of the FRP contribution to the shear strength of beams is essential for reliable design. Gene expression programming (GEP) has been widely utilized because it reliably expresses complex relationships between experimental variables. In this study, three new GEP models are proposed for three different strengthening configurations of FRP such as fully-wrapping, U wrapping, and side-bonding to predict the FRP contribution to shear strength. These models are developed using the most comprehensive database containing a total of 811 strengthened beams (350 fully-wrapped, 328 U-wrapped, and 133 side-bonded. Many variables have been considered in the proposed GEP models, including those that have been experimentally effective but are often neglected in existing literature equations, such as the shear span-to-effective depth ratio (a/d)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(a/d)$$\\end{document} and the stirrup ratio (ρw\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\rho }_{w}$$\\end{document}). Additionally, the reliability of existing equations in the literature and the proposed GEP models for predicting the FRP contribution to shear strength was statistically evaluated. As a result of this evaluation, the proposed GEP models for each strengthening configuration of FRP yielded the most accurate statistical results, with the lowest coefficient of variation (COV), and the highest coefficient of correlation (R).