Proposed Simulation Method Research Articles

Numerical and experimental investigation on the effect of tire on the 13° impact test of automotive wheel

The effect of tire on the wheel should be considered in detail in the process of simulating 13° impact test of the automotive wheel. However, due to the complexity and nonlinearity of the tire, the tire is usually simplified or neglected in the current simulation of wheel impact test, and these often lead to insufficient simulation accuracy. In this paper, a numerical simulation approach is proposed to evaluate the impact performance of wheel, in which the finite element model of tire is established in terms of the real tire. The physical wheel 13° impact tests are also performed, and the comparison between the simulation and experiment indicate that the proposed simulation method provides an efficient tool for predicting the impact performance of the wheel in wheel 13° impact test. Furthermore, the effects of tire on wheel are discussed by comparing the simulation and experiment results, and the results show the tire has a dual effect on wheel performance during the wheel 13° impact test.

A Dynamic Ice-structure Interaction Model for Prediction of Ice-induced Vibration

Sea ice crashing against offshore structures can cause strong ice-induced vibration and have a major impact on offshore structural safety and serviceability. This paper describes a numerical method for the prediction of ice-induced vibration when a vertical offshore structure is subjected to the impact of sea ice. In this approach, negative damping theory and fracture length theory are combined and, along with ice strength-stress rate curve and ice failure length, are coupled to model the internal fluctuating nature of ice load. Considering the elastic deformation of ice and the effect of non-simultaneous crushing failure of local contact between ice and structures, the present ice-induced vibration model is established, and the general features of the interaction process are captured. To verify its efficacy, the presented simulation methodology is subjected to a model test and two full-scale measurements based on referenced studies. Example calculations show good agreement with the results of the model test and full-scale measurements, which directly indicates the validity of the proposed simulation method. In addition, the numerical simulation method can be used in connection with FE programs to perform ice-induced vibration analysis of offshore structures.

Ex-ante online risk assessment for building emergency evacuation through multimedia data.

Ex-ante online risk assessment for building emergency evacuation is essential to protect human life and property. Current risk assessment methods are limited by the tradeoff between accuracy and efficiency. In this paper, we propose an online method that overcomes this tradeoff based on multimedia data (e.g. videos data from surveillance cameras) and deep learning. The method consists of two parts. The first estimates the evacuee position as input for training the assessment model to then perform risk assessment in real scenarios. The second considers a social force model based on the evacuation simulation for the output of training model. We verify the proposed method in simulation and real scenarios. Model sensitivity analyses and large-scale tests demonstrate the usability and superiority of the proposed method. By the method, the computation time of risk assessment could be decreased from 10 minutes (by traditional simulation method) to 2.18 s.

Influence of wear on hot banding migration of sealing ring using FEM

Hot banding is a typical thermoelastic instability phenomenon that occurs on the sealing surface of the sealing ring in a transmission. The presence of hot banding on sealing contact surfaces causes local wear. The wear of a sealing ring results in the loss of supply pressure and ultimately causes transmission failure. Local wear and hot banding migration also affect each other. This paper has discussed the influence of the wear of the sealing interface on hot banding migration using the general finite element method. A wear simulation procedure, based on Archard's wear law, was used to calculate the wear of the sealing ring, and the thermoelastic effects were also included in the simulation model. An iterative cyclic updating method was performed using the general finite element analysis software. The results of the simulation showed how wear influenced the migration of the hot banding. The worn sealing surfaces lead to more complex migration states of the hot banding, including division and combination of the hot banding. The proposed simulation method and the procedure that was used are suitable for trend analysis of seal design.

A New Method to Extract Gate Bias-Dependent Parasitic Resistances in GaAs pHEMTs

Accurate large signal GaAs pHEMT models are essential for devices’ performance analysis and microwave circuit design. This, in turn, mandates precise small signal models. However, the accuracy of small signal models strongly depends on reliable parasitic parameter extraction of GaAs pHEMT, which also greatly influences the extraction of intrinsic elements. Specifically, the parasitic source and drain resistances, R s and R d , are gate bias-dependent, due to the two-dimensional charge variations. In this paper, we propose a new method to extract R s and R d directly from S-parameter measurements of the device under test (DUT), which save excessive measurements and complicated parameter extraction. We have validated the proposed method in both simulation and on-wafer measurement, which achieves better accuracy than the existing state-of-the-art in a frequency range of 0.5–40 GHz. Furthermore, we develop a GaAs pHEMT power amplifier (PA) to further validate the developed model. The measurement results of the PA at 9–15 GHz agree with the simulation results using the proposed model.

Practical maneuvering simulation method of ships considering the roll-coupling effect

In this study, a practical maneuvering simulation method is presented considering the roll-coupling effect by extending an ordinal simulation model (3D-MMG model) proposed by Yasukawa and Yoshimura (J Mar Sci Technol 20:37–52, 2015), and adding the motion equation of roll. The roll moment acting on the hull is estimated by multiplying the hull lateral force with the vertical acting point. With respect to the surge force, lateral force, and yaw moment, the derivative expression model is employed. Subsequently, hydrodynamic derivatives with the exception of the roll-related terms are obtained by a captive model test based on the 3D-MMG model. The roll-related derivatives and the vertical acting point of the hull lateral force are estimated by simple formulae constructed based on the experimental data of four ship models. To validate the proposed simulation method, turning simulations are conducted for a pure car carrier model with variations in the metacentric height $${\overline{\mathrm{GM}}}$$ and are compared with free-running model test results. The simulation method exhibits sufficient accuracy with respect to its practical use and is useful to conventionally predict turning motions by considering the roll-coupling effect.

Pedestrian evacuation simulation under the scenario with earthquake-induced falling debris

Earthquake-induced collapse of building structures has been effectively controlled in recent years, however, failure of non-structural components and secondary disasters induced by falling debris remain a serious matter, making the outdoor evacuation more dangerous. A pedestrian evacuation simulation framework considering earthquake-induced falling debris is proposed herein, and the associated prediction model to calculate the falling debris distribution is also established. Moreover, experiments are conducted to quantify the influence of falling debris on pedestrian movement. After establishing the evacuation environment, a social force model is adopted to conduct the evacuation simulation. A case study of the teaching area located in Tsinghua University campus is performed using the proposed method for regional evacuation simulation. The results show that when considering the motion of debris after hitting the ground, the width of road covered by debris may be more than twice the first landing distance of debris, especially in densely built-up areas. Besides, whether the debris exists or not has more influence on the total evacuation time. The proposed method can assist with the identification of high-risk areas among the evacuation roads, as well as the provision of scientific basis for future urban planning and emergency evacuation drill development.

Evaluation of crack propagation and fatigue strength of rib-to-deck welds based on effective notch stress method

The fatigue data of tested specimens was referred to, and an additional three specimens were tested to obtain the crack section. The stress distribution, crack initiation position, and crack propagation path were compared with the effective notch-based numerical results. A simplified simulation of the fatigue test, considering the effect of welding residual stress, was also performed. The fatigue lives of tested specimens, as well as numerical results, were investigated in the effective notch stress system to investigate the feasibility of the effective notch stress approach. The results show that the effective notch stress approach is precise enough to determine the crack propagation path. The proposed simulation method for fatigue testing is demonstrated to be feasible when predicting the fatigue life, and the SWT parameter is found with higher accuracy by taking into consideration the welding residual stress. It is reasonable to assess the fatigue strength of rib-to-deck welds by the classification of FAT-225 recommended by IIW using an effective notch stress approach.

Sensor Fusion-based 3D Reconstruction by Two Sonar Devices for Seabed Mapping

We propose a sequential method to extract height information for 3D mapping by using sensor fusion of two sonar devices. The 3D reconstruction using sonar image from forward scanning sonar (FSS) is an ill-posed problem, thus we need additional constraints to extract 3D information from the sonar images. Our approach is to utilize complementary information from an additional sonar which is profiling sonar (PS) and geometric constraints between the installations of two sonars. Two sonars are fixed in the specialized installation, thus data from one sonar device can be converted into that of another one by using geometric constraints. The fusion process proceeds in three stages. The first stage is to carve out no object area using the occupancy grid mapping scheme. The second stage is to predict the elevation angle of the FSS by using the PS measurement and geometric constraints. The third stage is particle filtering using the generated particles by computing the weight and to collect the data of FSS. To verify the proposed method, we applied the proposed method in simulation and experiment in engineering basin with AUV.

A Direct Sinogram Correction Method to Reduce Metal-Related Beam-Hardening in Computed Tomography

This paper proposes a direct sinogram correction method that does not require metal segmentation and prior knowledge to reduce metal-related artifacts in polychromatic computerized tomography (CT). The metal-related artifacts, being common in dental conebeam CT images, are caused by beam hardening-induced sinogram inconsistency associated with complicated metal-bone-tissue interactions and other factors including scattering. This paper carefully analyzed artifact-causing factors and developed a direct method for sinogram correction to reduce the mismatch between sinogram data and the mathematical model for CT reconstruction. The proposed method attempts to project the beam-hardening affected data to the range space of the Radon transform so that the mathematical model is more consistent with the corrected data, with keeping a part of data where beam hardening effects are small. We tested the performance of the proposed method in numerical simulations and experiments using dental conebeam CT. The results demonstrate that the proposed method successfully reduces beam-hardening artifacts.

Analytical model of oil pipeline overground transitions, laid in mountain areas

Abnormal climate changes cause adverse physical and geographical processes (erosion of soils, waterlogging, flooding, etc.) over the world. This situation stipulates study on effect of soil foundation malleability on pipeline transition strength because of its important diagnostic value. The article develops an engineering approach for stress–strain state estimation of oil pipeline overground transitions, laid in mountainous areas. A mathematical statement was made and analytical solutions of the boundary-value problem were described, which take into account overland transition contact with soil foundation. In order to carry out the force analysis, a tubular rod simulated the oil pipeline contacting with the soil foundation on the adjacent to the overground transition section according to the Fuss-Winkler hypothesis. The overground transition was schematised with a thin-walled shell at the final stage of the assessment of strength. The maximum axial stresses were determined for overground transition operation, considering transition’s two-dimensional thermoelastic state. The final assessment of the strength was carried out according to the energy criterion. The proposed method for the overground transition simulation makes possible considering the soil foundation property effects on the behavior of the oil pipeline transition and presents the results in the form of concise analytical expressions convenient for engineering practice. The conducted researches showed the effect of significant redistribution of loading in the oil pipeline overground transition caused by changes of soil foundation stiffness. Also, the boundary effect of perturbation of the stressed state in adjacent underground sections was found. It was determined the zone sizes the boundary effect has significant manifestations. The boundary state of the pipeline is most often achieved in its lower fibers at a short distance from the edge of the underground section. The obtained results of researches were tested on real constructions of overground transitions of oil pipeline laid in mountainous areas.

An equivalent anchoring method for anisotropic rock masses in underground tunnelling

Rock bolting has been widely utilized for reinforcing underground openings, such as tunnels and mining. To ease the complexity of numerically simulating of the bolted rock mass, a novel method for equivalent anchoring simulates the reinforcement effect of the bolts by considering the anisotropic characteristics of the layered rock mass. The jointed material model in ABAQUS is improved by incorporating the anisotropy through the programming language FORTRAN. Based on the improved jointed material model, the equivalent anchoring parameters of the bolted layered rock masses are studied through a series of numerical tests. The numerical outcomes reveal that the improved jointed material model can be used to simulate the anisotropic features of the layered rock mass by comparing the classic and analytic solutions. The degree to which the supporting parameters affect the equivalent reinforcement performance are different in anisotropic rock masses, and the sensitivity of their influence is bolt length > bolt spacing > bolt diameter. Furthermore, an equivalent anchoring model for bolted rock masses (the formula of the improved parameter between the ratio of bolt length to tunnel diameter and the ratio of bolt diameter to bolt spacing) is proposed through numerical results analysis by the multiple linear regression method. An application case shows the field monitoring agreed well with the predicted vertical displacement of the tunnel demonstrating the feasibility of the proposed simulation method for the bolted rock mass. The results show the proposed method in this study can be conveniently utilized for efficient simulation of the mechanical behavior of bolted rock masses.

Distributed Hierarchical Control for State Estimation With Robotic Sensor Networks

This paper addresses active state estimation with a team of robotic sensors. The states to be estimated are represented by spatially distributed, uncorrelated, stationary vectors. Given a prior belief on the geographic locations of the states, we cluster the states in moderately sized groups and propose a new hierarchical dynamic programming framework to compute optimal sensing policies for each cluster that mitigates the computational cost of planning optimal policies in the combined belief space. Then, we develop a decentralized assignment algorithm that dynamically allocates clusters to robots based on the precomputed optimal policies at each cluster. The integrated distributed state estimation framework is optimal at the cluster level but also scales very well to large numbers of states and robot sensors. We demonstrate efficiency of the proposed method in both simulations and real-world experiments using stereoscopic vision sensors.

Welding effect on tensile strength of grade S690Q steel butt joint

In this study, welding effects on the tensile strength of high strength steel butt joints were investigated experimentally and numerically. Two butt joints were fabricated by joining two 8 mm thick reheated, quenched and tempered S690Q high strength steel (HSS) plates together using Shielded Metal Arc Welding with different welding heat inputs. In the experimental study, post-welding microstructure and micro-hardness tests performed for the butt joints confirmed the existence of a soft layer within the heat-affected zone. The size of this soft layer increased when higher heat input was adopted. Subsequent coupon tensile tests showed that the tensile strength of the butt joints deteriorated with the increase of the welding heat input. In numerical study, a finite element (FE) simulation considering the non-uniform material properties heat-affected zone was implemented to complement the experimental study. Comparisons between experimental and numerical results were carried out for the temperature history curves, failure modes and stress-strain curves for the coupons manufactured from the butt joints. It was found that the proposed simulation method could reflect the influence of welding process on the tensile strength of the S690Q HSS butt joints tested in this study.

Supporting Effects on Muscles of a Motion Assistive Wear Depending on the Fixture Position

As muscle weakness due to aging or fatigue potentially increases the risk of injuries or accidents, support wears may be needed that can play a role in assisting various motions. Recently, research and development of such support wears have gained momentum in order to measure a variety of their supporting effects. While in the research stage, they are designed and evaluated on the premise that they are carefully adjusted to fit the specific wearers’ physiques. However, in actually producing and using such support wears on sites, they pose a problem in that their supporting effects cannot sufficiently be felt because they are difficult to fix, or because they do not fit all body sizes. Therefore, in this study, we have quantitatively evaluated their assisting effects using simulations with a musculoskeletal model with a built-in functional underwear with support parts. In particular, we evaluated whether any differences in arrangement of support parts on the human body, due to their different fixture methods, will have an effect on their assisting effects. We have also developed a support wear, with easy to adjust support parts and fixture positions, and have verified the abovementioned simulation accuracies by myoelectric measurements. This verification found that the proposed simulation method can predict, to some extent, the impacts of any deviations in the support parts’ positions and their assisting effects.

Optimizing and evaluating biomarker combinations as trial-level general surrogates.

We extend the method proposed in a recent work by the Authors for trial-level general surrogate evaluation to allow combinations of biomarkers and provide a procedure for finding the "best" combination of biomarkers based on the absolute prediction error summary of surrogate quality. We use a nonparametric Bayesian model that allows us to select an optimal subset of biomarkers without having to consider a large number of explicit model specifications for that subset. This dramatically reduces the number of model comparisons needed. Given the model's flexibility, complex nonlinear relationships can be fit when enough data are available. We evaluate the operating characteristics of our proposed method in simulations designed to be similar to our motivating example. We use our method to compare and evaluate combinations of biomarkers as trial-level general surrogates for the pentavalent rotavirus vaccine RotaTeq™ (RV5) (Merck & Co, Inc, Kenilworth, New Jersey, USA), finding that the same single biomarker identified in our previously published analysis is likely the optimal subset.

Study on the critical loosening condition toward a new design guideline for bolted joints

An understanding of conditions that trigger the loosening of bolted joints is essential to ensure joint reliability. In this study, a three-dimensional finite element model of a typical bolted joint is developed, and a new simulation method is proposed to quantitatively identify the critical transverse force for initiating loosening. This force is used to evaluate the anti-loosening capacity of bolted joints. Using the proposed simulation method, the effects of factors affecting critical loosening are systematically studied. It is found that the preload, frictional coefficients at the thread and the bearing surfaces, clamped length, and fit tolerance mainly affected loosening. When the preload and friction coefficients are increased, and the clamped length and fit tolerance are reduced, loosening is inhibited. Experiments are performed to demonstrate the reliability of the results. Finally, a suggestion is proposed to improve the design guideline VDI 2230 for bolted joints, which considers the requirement of avoiding loosening under vibrational loading.

Geometric simulation of 5-axis hybrid additive-subtractive manufacturing based on Tri-dexel model

5-axis hybrid additive-subtractive manufacturing is a new and promising technology for many industrial applications. Because of its complexity, the machining simulation is very important to verify the effectiveness of tool path. However, most simulation methods are proposed for subtractive manufacturing and additive manufacturing separately. This paper presents a novel geometric simulation technique for the 5-axis hybrid additive-subtractive manufacturing, which is based on Laser Engineered Net Shaping (LENS) and milling. In the proposed method, 5-axis additive swept volume elements are represented with Tri-dexel models and then converted into triangular meshes for visualization. Workpiece after additive manufacturing can be then used as a workblank for subtractive manufacturing simulation. Finally, a geometric simulation module is developed based on SIEMENS NX software to demonstrate the feasibility of the proposed simulation method.

Monte Carlo simulation of X-ray backscatter detection for the seam tracking when welding sandwich panels

The I-core sandwich panels are widely utilized in manufacturing lightweight structures in a variety of fields, such as aviation, aerospace, shipping, and so on. However, due to their structural characteristics, it is difficult to track the weld seam automatically in the welding process. At present, a detection method based on the backscattered X-rays is widely used for seam tracking of the sandwich panels. The conventional modelling based on analytical method has been applied in the simulation of X-ray backscatter detection system, but analytical method has a deviation from the actual situation under the low X-ray intensity. In this paper, a simulation model based on Monte Carlo method is proposed to simulate the X-ray backscatter detection system for the automatic seam tracking in the welding of such sandwich panels. The effect of photon energy and beam intensity on the detector counting is analysed. The result shows that the proposed method can accurately simulate the X-ray backscatter detection system for the automatic seam tracking when welding sandwich panels; the proposed simulation method can provide more accurate simulation results and more time domain information of photons at a relatively low beam intensity. The proposed method can also provide information as a basis for the optimization of the X-ray backscatter detection system at a relatively low dose.

A new approach to modeling liquid intrusion in hydrophobic fibrous membranes with heterogeneous wettabilities

The current paper presents an energy minimization method, implemented in the Surface Evolver code, for tracking the air–water interface intrusion in a hydrophobic fibrous membrane and thereby studying the effects of the membrane’s microstructure on its resistance to water intrusion (i.e., membrane’s liquid entry pressure). The simulation method developed in this work is computationally affordable and it is accurate in its predictions of the air–water interface shape and position inside the membrane as a function of pressure (and the size or contact angles of the fibers). Due to challenges in applying the present interface tracking method to membranes having highly complex internal microstructures (e.g., media comprised of dissimilar fibers with random three-dimensional orientations), this study is limited to membranes comprised of orthogonally oriented fibers. Application of the proposed simulation method in studying effects of fiber diameter or contact angle heterogeneity on water intrusion pressure is demonstrated for such orthogonal fibrous structures.