Numerical Analysis Software Research Articles

Development and verification of rutting prediction model based on variable frequency load test

ABSTRACT An innovative rutting test method was developed based on the existing rutting prediction model to improve the rutting prediction model used in the asphalt pavements. The loading mould was improved based on test requirements and equipment characteristics, and small-scale and full-scale variable frequency load rutting tests were conducted. Nonlinear multiple regression analysis was conducted on the test results using numerical analysis software, converting driving speed into loading frequency and incorporating it into the rutting prediction model. This resulted in a permanent deformation prediction model for asphalt mixtures, incorporating factors such as temperature, pressure, loading cycles, loading frequency, and pavement thickness. Fourteen highways were selected as validation sections. The validation results showed that the average error of the prediction model established in this study was 15.48%, compared to 24.42% and 27.94% for the other two models. For different grades of highways, the load frequency parameter can distinguish the rutting conditions under different driving speeds, making the rutting prediction model established in this study more accurate compared to measured values.

A Study on a Radio Source Location Estimation System Using High Altitude Platform Stations (HAPS).

Currently, there is a system in Japan to detect illegal radio transmitting sources, known as the DEURAS system. Even though crackdowns on illegal radio stations are conducted on a regular basis every year, the number of illegal emission cases still tends to increase, as ordinary citizens are now able to handle advanced wireless communication technologies, e.g., via software-defined radio. However, the current surveillance system may not be able to accurately detect the source in areas where large buildings are densely packed, such as urban areas, due to the effects of reflected waves. Therefore, in this study, we proposed a system for estimating the location of the source of transmission using a high-flying unmanned aerial vehicle called HAPS. The simulation results using numerical analysis software show that the proposed system can estimate the location of the source over a wider area and with higher accuracy than conventional monitoring systems.

Vibration-based damage detection of beams using Hybrid Genetic Algorithm with combined l0 and l1 regularization

Vibration-based damage detection is an effective way of identifying beam damages before they become severe and potentially catastrophic. This paper introduces a novel and robust method for detecting multiple cracks in beams using a Hybrid Genetic Algorithm (HGA). The objective function of the proposed method, based on dynamic properties, can be employed with partial modal information and is enhanced by including the initial residuals between numerical and experimental models along with combined l0 and l1 regularization. This enhancement mitigates the impact of limited modal data, experimental noise, and modeling inaccuracies. Additionally, a method of selecting an appropriate regularization parameter by analyzing residual and solution norm curves is presented. The performance of the proposed method is evaluated and verified using both numerical simulations and experimental studies on a steel cantilever beam under four damage scenarios. In the experimental study, natural frequencies and mode shapes were determined under ambient vibration conditions using Enhanced Frequency Domain Decomposition (EFDD) and the Stochastic Subspace Identification (SSI) method. Finite element models of the beam were developed in ABAQUS software for numerical analysis, and a comparative study of numerical and experimental data was conducted. The proposed approach successfully identifies, locates and quantifies single and multiple damages in the beam, demonstrating its reliability and effectiveness, particularly in scenarios with limited modal data and significant experimental noise.

Analysis of fire protection design strategies for commercial renovation of villagers’ self-built houses

Abstract The current situation of self-built houses by villagers is prevalent in rural areas, where many villagers construct their own residential dwellings based on their personal needs and economic circumstances. These self-built houses are typically constructed using basic materials and traditional building techniques, often without adherence to strict building regulations and standards. As a result of the lack of professional knowledge and technical guidance, the structural integrity and safety of these houses are often compromised. In addition, the lack of firefighting facilities and fire prevention measures further increase the risk of fire accidents. This situation contributes to a higher incidence of fires in rural areas, posing a significant threat to the lives and assets of villagers. Therefore, it becomes imperative to improve the current state of self-built houses by villagers. Strengthening fire safety awareness and implementing robust fire prevention measures are vital in this regard. This paper aims to summarize the challenges involved in fire protection design for renovating rural buildings. Additionally, it proposes fire protection design principles specifically for the commercial transformation of self-built houses by villagers. By analyzing real-world engineering cases, this study puts forth specific fire protection measures concerning fire rescue, fire control zones (groups), evacuation design, and fire systems. To ensure the fire safety of these buildings, special fire protection design methods are employed. The effectiveness of the proposed fire protection measures are validated through the use of FDS fire and smoke numerical simulation analysis software and Pathfinder evacuation simulation software, ensuring the fire safety of the buildings. The results show that the available safe evacuation time that can be provided by this scenario is 1200 s as calculated by the FDS simulation, and the necessary safe evacuation time is less than the available safe evacuation time in case of a fire on the first floor of this building, and the safe evacuation of the people can be guaranteed. This study can provide a valuable resource for architects, engineers, and decision makers to implement effective fire protection measures during commercial remodeling of village-owned houses.

Numerical simulation analysis of slope stability from rainwater utilizing the Civil3D+Flac3D coupling

Building Information Modeling (BIM) technology serves as an effective means for engineering modeling and information integration, surpassing traditional two-dimensional approaches with its superior spatial analysis capabilities. While BIM has gained widespread applications in slope engineering, a gap persists in the integration between protective design and simulation analysis in terms of slope stability. This study employs literature review, theoretical analysis, software development, and numerical simulation methods to explore the application of BIM models in slope stability analysis. Through the integrated application of BIM model construction, mesh subdivision, and stability analysis, we address the deficiency in three-dimensional slope stability inherent in BIM by coupling Civil3D’s secondary development with Flac3D, a numerical simulation software. This approach not only addresses the shortcomings of numerical analysis software in constructing complex geological models but also employs a collaborative multi-software approach for comparison to validate its suitability in slope engineering. The results demonstrate that models built using BIM software are more comprehensive and possess high precision in numerical simulation, thus exhibiting significant practical value in real-world engineering applications.

Damage characteristics of gas extraction boreholes under different crustal stresses and their effects on gas extraction

AbstractTo investigate the effects of different crustal stresses on the stability of gas extraction boreholes, several equations were deduced. Additionally, the coupled flow‐solid model of gas extraction was constructed, given the elasticity−plasticity deformation of the coal body. Using the numerical simulation and analysis software of Comsol, a study was conducted on the deformation and damage of gas extraction boreholes under different crustal stresses. The results are as follows: with vertical stress increasing, the concentration area of shear stress, deformation amount, and the area of the plastic zone around the hole increase. Varied lateral pressure coefficients led to differing distribution positions of shear stress concentration areas and plastic zones around the hole. An increase in lateral pressure coefficient shifted the distribution positions of shear stress maximum. In addition, plastic zone, and permeability ratio maximum change from the left and right sides of the borehole to the upper and lower sides, and the larger the lateral pressure coefficient is, the worse the stability of the upper and lower sides of the borehole is. Higher lateral pressure coefficients inhibited extraction, with the effect becoming more pronounced over time. Elevated vertical stress and lateral pressure coefficients hindered negative pressure propagation in the borehole.

Development of a Fiber Bragg Grating accelerometer based on a tandem single-notched hinge structure

A Fiber Bragg Grating low-frequency accelerometer with a single-notched hinge in series is proposed to improve the hinge structure’s sensitivity and the cross-sensitivity of the accelerometer of low-frequency seismic waves. The sensitivity and the cross-sensitivity of the accelerometer are improved by connecting the single-notched hinge structure in series and experimentally verified. Based on the theoretical analysis, the resonance frequency and sensitivity formula of the accelerometer are derived. At the same time, the accelerometer is simulated by finite element analysis software to simulate and analyze the characteristics of the accelerometer in terms of resonance frequency, strain distribution, and amplitude-frequency response. The structural parameters of the accelerometer are optimized by numerical analysis software, and the effects of the structural parameters on the sensitivity and resonance frequency of the accelerometer are analyzed. The experimental results show that the resonance frequency of the accelerometer is 110 Hz, the flat region is 0.6–50 Hz, the linearity is as high as 98.9%, the sensitivity is 1040.41 pm/g, and the cross-sensitivity of the accelerometer in the flat interval is 4.94%. This indicates that the accelerometer shows good linearity and cross-sensitivity in the flat interval, which well meets the needs of seismic wave signal monitoring in low-frequency oil and gas exploration.

Evaluation of Thermomechanical Properties in a 2D Rotational Elastocaloric Prototype: A Numerical Study for Enhanced Energy Efficiency

So far, much of the research on the caloric effect has focused on the magnetocaloric effect, which was the first investigated chronologically, in the field of room temperature for about 40 years. Subsequently and especially in the last decade, scientific research has focused on the development of solid-state technologies other than the magnetocaloric one, including the one of interest for this work: elastocaloric technology. This work is part of the “SUSSTAINEBLE” project of the Department of Industrial Engineering at the University Federico II of Naples, aimed at developing the first Italian prototype of an elastocaloric device for environmental conditioning. The prototype is currently in the experimental development phase and its design and construction are dynamically accompanied by a two-dimensional numerical model that fully reproduces its thermo-fluid dynamic operation. The rotary-type prototype consists of 600 Nickel Titanium wires subjected to loading and unloading phases controlled by a properly programmed optical encoder. The thermo-fluidic medium that regulates heat transfer is air. The aim is to characterize the operation of the elastocaloric device using numerical analysis software in order to optimize its geometric, operational, and environmental parameters, to maximize its energy performance in terms of temperature difference, useful thermal power, and coefficient of performance.

Numerical simulation of leakage jet flame hazard of high-pressure hydrogen storage bottle in open space

The jet fire is a common type of fire accident in high-pressure hydrogen storage bottles. It is crucial to conduct research on the thermal radiation hazards resulting from on-board hydrogen storage bottle leaks, leading to jet fires within 35 MPa. Additionally, accurately and swiftly calculating the characteristic parameters of hydrogen jet flames, such as flame geometry and radiation heat flow, is of utmost importance. To study the jet fire hazard caused by high-pressure hydrogen storage cylinder leaks, a simplified model of the hydrogen storage cylinder was established using FLUENT software for numerical simulation analysis. The study analyzed the impact patterns of high-pressure hydrogen leakage jet flames under different scenarios, including leakage aperture, leakage pressure and ambient wind speed. The results demonstrate a positive correlation between the leakage aperture and pressure with the size of the jet flame and the extent of thermal radiation damage. The larger the leakage aperture and pressure, the larger the hydrogen jet flame size. The higher the peak value of the flame thermal radiation, the greater the hazard range. Additionally, the temperature of the stable axis of the jet flame rises with increasing leakage aperture. As the leakage pressure rises, the thermal radiation of the flame also increases. Conversely, as the ambient wind speed increases, the flame length, the burn radius, and the thermal radiation range decreases, but the high-temperature heat range expands. The empirical formula between flame length and leakage pressure and leakage aperture under different environmental wind speeds is obtained by data fitting, which can be used as a priori prediction of flame length under wind speed conditions.

Simulation of exchange processes in multi-component environments with account of data uncertainty

The goal of the work. Proposals for methods of solving systems of linear homogeneous and non-homogeneous differential equations with constant and variable coefficients that defined in interval form and intended for modeling exchange processes in multicomponent environments. Research subject: systems of linear homogeneous and non-homogeneous differential equations with constant and variable coefficients defined in interval form. Research method: interval analysis. The obtained results. Systems of linear homogeneous and non-homogeneous differential equations, which are used in modeling exchange processes in multicomponent environments, are considered. Such systems can be considered, for example, in problems of chemical kinetics, materials science, and the theory of Markov processes. To obtain the solution of these equations, specialized calculators of analytical transformations were used and tested. The Matlab system (ode15s solver) was used for numerical analysis of systems of differential equations. It is shown that the application of interval methods of numerical analysis at the initial stage of system modeling has some advantages over probabilistic methods because they do not require knowledge of the laws of distribution of the results of the system state parameter measurements and their errors. It is shown that existing methods of solving systems of linear differential equations can be divided into two groups. Common to these groups is the use of interval expansion of classical methods for solving differential equations given in interval form. The difference between these two groups of methods is as follows. The methods of the first group can be used for all types of differential equations but require the creation of special software. The peculiarity of the methods of the second group is that they can be used to solve equations analytically or using numerical analysis packages. The application of the methods of the second group is shown on the example of solving a system of differential equations, the coefficients of which are determined in interval form. The system of these equations is intended for modeling the processes of exchange with the external environment of the elements of the model of a specific physical system. In the case when the coefficients of these equations are variables, their piecewise-constant approximation is applied and a criterion that determines the possibility of its application is given. The technique proposed in the paper can be applied to solve systems of linear homogeneous and non-homogeneous differential equations with constant and variable coefficients if they are given by slowly varying functions. In the case when the coefficients of the equations are determined in the interval form, the technique allows obtaining their solution also in the interval form and does not require the creation of special software.

Numerical Simulations of Failure Mechanism for Silty Clay Slopes in Seasonally Frozen Ground

Landslide damage to soil graben slopes in seasonal freezing zones is a crucial concern for highway slope safety, particularly in the northeast region of China where permafrost thawing is significant during the spring. The region has abundant seasonal permafrost and mostly comprises powdery clay soil that is susceptible to landslides due to persistent frost and thaw cycles. The collapse of a slope due to thawing and sliding not only disrupts highway operations but also generates lasting implications for environmental stability, economic resilience, and social well-being. By understanding and addressing the underlying mechanisms causing such events, we can directly contribute to the sustainable development of the region. Based on the Suihua–Beian highway graben slope landslide-management project, this paper establishes a three-dimensional finite element model of a seasonal permafrost slope using COMSOL Multiphysics 6.1 finite element numerical analysis software. Additionally, the PDE mathematical module of the software is redeveloped to perform hydrothermal-coupling calculations of seasonal permafrost slopes. The simulation results yielded the dynamic distribution characteristics of the temperature and seepage field on the slope during the F–T process. The mechanism behind the slope thawing and sliding was also unveiled. The findings provide crucial technical support for the rational analysis of slope stability, prevention of sliding, and effective control measures, establishing a direct linkage to the promotion of sustainable infrastructure development in the context of transportation and roadway engineering.

Influence and the Control of Shield Tunneling on Ancient Tower Vibration

In recent years, to effectively mitigate the issue of urban traffic congestion, tunnels have become widely used new type of road. However, when the soil layer is excavated and disturbed, the resulting vibration affects the safety of the buildings above it, especially for ancient buildings that are very sensitive to vibrations. Taking the White Tower in Hangzhou as an example, in this paper, the vibration response propagation of large-diameter shield tunnel excavation to adjacent ancient towers is studied through field measurements. The vibration response of the unexcavated south line tunnel is predicted by using 3D numerical analysis software, and the optimal construction parameters are obtained. The study found that the frequency domain component of the White Tower bedrock vibration caused by shield tunneling is mainly 5–20 Hz, and the vibration response attenuates significantly beyond 40 m. Further, reducing the propulsive force can reduce the vibration response of the White Tower; therefore, controlling the propulsion and reducing the tunneling velocity can reduce the vibration response.

Optimization of stope structure parameters by combining Mathews stability chart method with numerical analysis in Halazi iron mine

When employing the open stope mining method for extracting materials in underground mines, it is necessary for personnel and equipment to operate within a specified range of the goaf area, thus, adoption of appropriate mining parameters in the mining field is crucial for promoting safe production practices. In this study, the Harazi iron mine is taken as the research subject, with theoretical analysis combined with numerical simulation that enables the authors to simulate and analyze the width parameter of the mining field. Theoretical analysis utilizing the Matthew stability chart method confirms that the width of the mining field in Harazi iron mine should not exceed 9 m. Based on this finding, the mechanical response characteristics accompanying the mining process at different widths within the mining field limits are analyzed via the Flac3D numerical analysis software. As a result of this analysis, the optimal width of the mining field in Harazi iron mine is determined to be 8 m. The method utilized in this article provides a rational approach to determining structural parameters of the mining field and can effectively aid in promoting mine safety practices.

Constitutive Modelling of the Cyclic Response of Unsaturated Soils: A Discussion of the State‐of‐Art

Site response analysis (SRA) is an important aspect of seismic design that considers the impact of local site conditions on the ground response during earthquakes and plays a key role in the design of structures that interact or are made with soil. Although previous studies have demonstrated that factors such as the degree of saturation influence the site response, incorporating partial saturation into analysis has not been widely practiced. Numerical analysis tools exist; however, they are often unable to directly assess the influence of partial saturation, especially under seismic conditions. This is often caused by the missing implementation of constitutive models and finite elements able to account for partial saturation of soils under cyclic conditions. For this reason, a review of the most common constitutive models developed with a view to describing unsaturated soil behaviour subjected to cyclic loads is presented, followed by a critical discussion on their applicability to finite element frameworks, with the aim of providing a wide panorama of the available constitutive platforms suitable for implementation in numerical codes. Therefore, we present and discuss the mechanical and hydraulic properties of the constitutive models that can be applied to the analysis of boundary value problems, and specifically for SRA, focusing on partially saturated soils under cyclic loading conditions. It was observed that many constitutive model frameworks for cyclic loadings are based on the bounding surface or two‐surface theories, and some of them are coupled with hydraulic behaviour through the Soil Water Retention Curve (SWRC) or its variations. Two main approaches were identified based on the mechanical features, while regarding the hydraulic behaviour, the main distinction lies in the selected SWRC. Furthermore, certain constitutive models have been implemented in finite element software for numerical analysis of geotechnical earthquake engineering problems.

Kaynaklı Çelik Birleşimlerin Yorulma Analizinde Kullanılan Temel Yaklaşımların Gözden Geçirilmesi

Fatigue damage occurs in welded steel joints under cyclic loads. These joints are particularly vulnerable to fatigue due to high stress concentrations. Today, with the developing numerical analysis software, fatigue life calculations are carried out with different methods based on the fatigue life and the stresses that will occur in the elements. These methods, which may differ from each other, examine the stress distributions occurring under different loading conditions and the initiation, development and collapse of the damage occurring in the element. Fatigue analysis methods are divided into two groups as local and global approaches. In global methods, the critical stress that will occur on the entire structure is considered, while local geometry and local parameters are examined in local methods. This study presents fatigue analysis methods of welded steel joints.

Fiber Bragg Grating low-frequency accelerometer based on spring structure

To meet the needs of accelerometers for seismic wave monitoring in the field of low-frequency oil exploration, a Fiber Bragg Grating (FBG) low-frequency accelerometer based on spring structure is proposed. The accelerometer consists of two FBGs, two semi-profile metal capillaries, a spring, and a mass block. In addition, the accelerometer is encapsulated in a cylindrical housing to enhance its stability. Firstly, the working principle of the accelerometer is introduced in detail and the theoretical model of the accelerometer is established, then the accelerometer is simulated by finite element analysis software and the dimensional parameters of the accelerometer are optimized by numerical analysis software. Finally, the experimental study of the accelerometer is carried out to test the shock response, amplitude-frequency response, and sensitivity response of the accelerometer. The experimental results show that the proposed new accelerometer has a resonant frequency of 115 Hz, dynamic resolution up to 0.123 mg/Hz in the operating range 0.5–60 Hz, the sensitivity is 932.25 pm/g, the linearity is up to 99.9 %, the higher sensitivity, and sufficient operating range, so that the accelerometer is expected to be used in the field of low-frequency oil exploration.

INFLUENCE OF INTERLAYER HYBRIDITY, LAYING ANGLESON FREE VIBRATIONS ANDDEFORMATION CHARACTERISTICS

Natural frequencies and modes of vibration, the rigidity of solids, are the most important parameters taken into account when designing structural elements in order to take into account dynamic loading conditions. The article presents the results of calculating the natural frequencies of the first forms of bending vibrations of composite plates with interlayer hybridity. The dependences of the deflections of the rods under the action of a distributed load over the surface on the internal structure are revealed. The calculations were obtained by numerical and approximate methods. For numerical analysis software based on the finite element method (ANSYS) was used.

Development of a low-frequency accelerometer based on symmetric multi-stage triangular beam fiber Bragg grating

In order to meet the needs of accelerometers for low-frequency seismic exploration, a fiber-optic grating accelerometer based on a symmetric multi-stage triangular hinge is proposed. The sensitivity of the accelerometer is improved by the symmetrical multi-stage triangular beam structure, and experimental verification is carried out. The resonant frequency and sensitivity equations of the accelerometer are given based on theoretical analysis, while the finite element analysis software is used to simulate and analyze the characteristics of the accelerometer such as resonant frequency, stress distribution, and amplitude-frequency response. The structural parameters of the accelerometer are optimized by numerical analysis software, and the influence of the structural parameters on the sensitivity and resonant frequency of the accelerometer is analyzed. The experimental results show that the accelerometer has a resonant frequency of 140 Hz and a linearity of 99.9 % in the flat region of 1–70 Hz, a sensitivity of 337.325 pm/g, and an interference immunity of 5.39 % in the lateral direction in the working axis direction. This indicates that the accelerometer shows good linearity and lateral interference immunity in the flat interval, which well meets the needs of seismic wave signal monitoring in the field of low-frequency oil and gas exploration.

Radiant Thermal Test System for Turbine Blades Using a Novel Pattern Search Algorithm

Abstract We established and validated a radiant thermal test system using a miniaturized quartz lamp heating device designed with a novel search algorithm to meet aero-engine blade heating requirements. The device can perform rapid, high-temperature gradient tests on new-material aero-engine blades, which cannot be achieved through electromagnetic induction. The algorithm, derived from the Monte Carlo method (MCM) and pattern search, can solve the problems of the classical iterative search algorithm by searching lamp parameters and reducing the algorithm's time complexity. These searched power parameters enable the system's closed-loop control to achieve temperature gradients easily. The corresponding heating process was also simulated using commercial numerical analysis software, serving as a numerical validation for the algorithm-based system. The device could meet the thermal fatigue test requirements for the blade at six different temperature control points, including a maximum temperature exceeding 1150 K, a maximum temperature difference exceeding 160 K within 20 mm, and a heating rate exceeding 30 K/s. Thus, the device provides a promising technique for rapid, high-temperature heat treatment of complex small components, and the algorithm makes designing miniaturized quartz lamp heating devices more accessible and versatile for small components.

Analysis of Debonding Failures of the Screen and Case during Tablet Drop

In recent years, due to the increasingly powerful functions of tablets, more and more people have used tablets. The failure of the screen caused by debonding failure between the screen and the case of the tablet due to drops will affect the normal use of the tablet. However, there have been few studies on the debonding methods of the screen and the case of the tablet, as well as the factors influencing the debonding between the screen and the case of the tablet. Numerical analysis software was used in this paper to simulate the iPad Air (Air) drop process, and the cohesive zone model and tiebreak contact were used to simulate the debonding process between the screen and case of the Air tablet, respectively. When the results are compared to the experiments, the results show that the cohesive zone model is superior. The effects of various rounded corner radii, drop postures in the XY plane, materials of the outer case, and strain rates of PC/ABS on the localized debonding between the outer case and outer glass of the Air during the drop process were investigated. The degree of debonding between the Air model’s outer case and outer glass is defined by t, which is the ratio of the area of the deleted cohesive elements to the total area of the cohesive elements. The results show that the rounded corner radius and the strain rate of PC/ABS have less influence on t; the t of the Air model dropped at 45° in the XY plane is 37.7% of that dropped at 0° and 90°; and the t of the Air model with glass as the outer case material is 48% of that with aluminum alloy as the outer case material. These studies serve as a foundation for tablet design and material selection.