Detailed Stress Research Articles

Failure prediction of irregular arranged multi-bolt composite repair based on finite fracture mechanics model

A numerical method based on the finite fracture mechanics model was proposed in this study to accurately predict the failure of irregular arranged multi-bolt composite repair. The stress distribution and the stress intensity factors required in the model were obtained using a two-stage analysis strategy, which can effectively lower the FE model scale and computational cost while keeping high computational accuracy. In the two-stage analysis strategy, the bolt load distribution was calculated using the global analysis method. After obtaining the fastener load from the first-level model, detailed stress and stress intensity factor analysis were conducted around individual fasteners and cutouts, which were then used to evaluate the failure behaviour of the composite panels. To validate the numerical method, tensile tests were carried out on three kinds of bolted composite repairs with circular, elliptical and oblong cutouts. Failure mode, failure location and failure strength predicted by the proposed numerical method were consistent with the experimental results, illustrating the effectiveness and applicability of the numerical method on predicting the failure behaviour of bolted composite repairs.

Cationic etching of ZIF-67 derived LaCoO3/Co3O4 as high-efficiency electromagnetic absorbents

• Perovskite/spinel type LaCo 3+ 1-2 δ Co 2+ 2 δ O 3- δ /Co 3 O 4 polycrystals were synthesized via La 3+ etching method based on ZIF-67. • The heterointerfaces and lattice distortions were confirmed via a refinement treatment (Rietveld analysis). • The phase ratio and oxygen vacancy in crystals were analyzed. • The f E of S2 reached 6.88 GHz with RL min of −38.40 dB at 2.8 mm. The f E of S1 reached 4.56 GHz at 2.00 mm. Given the urgent requirement of electromagnetic (EM) radiation defensive and self-power EM energy infinite vitality deliverers, high-efficiency EM absorbents are highly proposed. Herein, a series of hierarchical N-hybridized carbon-based polycrystalline EM absorbents containing perovskite type LaCoO 3 and spinel type Co 3 O 4 have been successfully synthesized via a controllable cationic etching technique based on ZIF-67. By adjusting the molar ratio between water and ethanol in etching solvents, polycrystals with tunable morphologies, crystalline structures, dielectric and magnetic properties can be obtained. Especially, the multiple phase properties were studied via a refinement treatment (Rietveld analysis) of X-ray diffraction (XRD), illustrating the existence of heterogeneous interfaces and lattice stress and distortions in details. The non-stoichiometric lattice O (O vacancy) in LaCo 3+ 1-2 δ Co 2+ 2 δ O 3- δ /Co 3 O 4 polycrystals and LaCo 3+ 1-2 δ Co 2+ 2 δ O 3- δ single crystalline perovskite were characterized by XPS ( δ = 0.19, 0.12 and 0.03). Responsible to the synergistic optimization of EM attenuation and impedance matching effect caused by the strengthening of interfacial polarization and dipoles polarization, the polycrystalline samples exhibited excellent EM absorbability. In details, the minimum reflection loss (RL min ) and effective absorption band width ( f E ) reached −45.91 dB and 5.6 GHz respectively at 12.48 GHz with a thickness at 2.7 mm, when there were 25% water in etching solution. Noteworthily, the f E of polycrystal obtained via 50% water reached 6.88 GHz with a device thickness of 2.8 mm.

Time Response Stress Analysis of Solid and Reinforced Thin-Walled Structures by Component-Wise Models

This paper deals with the evaluation of time response analyses of typical aerospace metallic structures. Attention is focussed on detailed stress state distributions over time by using the Carrera Unified Formulation (CUF) for modeling thin-walled reinforced shell structures. In detail, the already established component-wise (CW) approach is extended to dynamic time response by mode superposition and Newmark direct integration scheme. CW is a CUF-based modeling technique which allows to model multi-component structures by using the same refined finite element for each structural component, e.g. stringers, panels, ribs. Component coupling is realized by imposing displacement continuity without the need of mathematical artifices in the CW approach, so the stress state is consistent in the entire structural domain. The numerical results discussed include thin-walled open and closed section beams, wing boxes and a benchmark wing subjected to gust loading. They show that the proposed modeling technique is effective. In particular, as CW provides reach modal bases, mode superposition can be significantly efficient, even in the case of complex stress states.

In-vivo blood flow parameters can predict at-risk aortic aneurysms and dissection: a comprehensive biomechanics model

Abstract Background Abnormal blood flow patterns can alter the material properties of the thoracic aorta via altered vascular biology and tissue biomechanics. In-vivo haemodynamic assessment of the aorta is yet to penetrate clinical practice due to our limited understanding of its effect on aortic wall properties. The decision for surgical treatment is based on size thresholds, limited to a single measurement of aortic diameter from routine imaging, although many aortic dissections (40–60%) occur below these size thresholds. This multi-centre study aims to assess the clinical utility of biomechanics principles in thoracic aortic aneurysm (TAA) risk rupture prediction using a substantial sample size. Methods Fifty-five patients undergoing surgery for root or ascending TAA were recruited from five cardiac centres. Bicuspid aortic valves and connective tissue disease were excluded from this study.Haemodynamic assessment Pre-operative 4-dimensional flow magnetic resonance imaging (4D-MRI) were conducted. Direct 4D-flow analysis and computational fluid dynamics (CFD) were performed creating detailed wall shear stress (WSS) maps across the whole aneurysms. Aortic wall assessment The aneurysmal aortic sample was obtained from surgery and subjected to region specific uniaxial failure tests in the circumferential and longitudinal directions, as well as delamination testing within the aortic media. Whole aneurysm histological characterisation was also conducted using computational pathology techniques. Blood flow, tissue mechanics and microstructural properties were used to develop a risk prediction model with assessment of elastin, collagen and smooth muscle cell composition, as well as failure strain assessment and dissection energy function. Results Outcomes of mechanical properties were: Young's Elastic Modulus as a measure of aortic stiffness (0.85 MPa ±0.69), as well as maximal tensile strength (0.49 MPa ± 0.36), which demonstrated reduced aortic wall strength in the outer curvature. This correlated with increased wall shear stress (WSS) (up to 10 Pa) and flow velocity (up to 43 l/min). Regions of abnormal flow and tissue mechanics correlated significantly with degraded medial microstructure (elastin abundance: 34 vs 66%; collagen abundance 26 vs 57%, p<0.05). Conclusions CFD modelling has the potential to provide a risk prediction of acute events in TAA beyond the current size classification, as validated by altered aortic tissue properties. Future longitudinal studies are warranted to validate this methods in moderately enlarging thoracic aortas. Flow, mechanical, histology properties Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): NIHR Imperial College BRC

Tunneling cracks in arbitrary oriented off-axis lamina

The steady-state energy release rate for tunneling cracks under mixed-mode loading is determined using finite element analyses. The balanced and symmetric laminate layup $$[0/\theta /0/-\theta ]_s$$ is investigated, where the tunneling crack is located parallel to the fiber direction of the central off-axis oriented layer. It is found that for the steady-state situation, a simple energy balance calculation of the released energy of the separated crack surfaces for a fully developed crack gives the same value as the average value of a detailed J-integral analysis of the crack front. Furthermore, the crack front mode-mixity, obtained by the same energy balance calculation, was found to give a good prediction of the average mode-mixity found from a detailed stress intensity calculation along the crack-tip. Based on this simplified energy balance approach, the energy release rate is determined for all angles $$\theta \in {]}0;90]^{\circ }$$ for orthotropic elastic properties ranging from typical low modulus glass fiber reinforced polymers to high modulus carbon fiber reinforced polymers. The predicted results can be used to investigate the influence of the layup angles on static and fatigue tunnel crack evolution in composite materials used within, e.g. automotive, aerospace, and wind energy applications.

Tensile bearing capacity for bolted spherical joints with different screwing depths of high-strength bolts

Aiming at evaluating the reliability of the high-strength bolts’ fake tightened-up phenomena of the bolted spherical joints in a spatial grid structure, this research studied the tensile strength, stiffness, and failure modes of the bolted spherical joints with different bolt types and screwing depths using a combined method of the lab experiments and numerical simulations. A total of 40 axial tension tests of the bolted spherical joints were conducted with five different bolt types and eight different screwing depths. The test results showed that the bolted spherical joints with the different bolt screwing depths of high strength bolts suffered three failure modes, namely, the thread failure, bolt fracture failure, and sphere rupture failure. Validated by its feasibility and accuracy, the proposed numerical simulation method of the bolted spherical joints can estimate the ultimate strengths and failure modes, as well as the detailed stress distribution and failure development process. According to the test and numerical analysis results, a group of calculation formulas was developed for predicting the tensile strength of bolted spherical joints with different bolt screwing depths.

Design of a disk-mandrel assembly for achieving rotational autofrettage in the disk

Rotational autofrettage is a recently proposed method to induce beneficial residual stresses in axisymmetric hollow cylindrical bodies. The feasibility of the process has been studied for both disks and cylinders used in many engineering applications. The earlier analyses of rotational autofrettage of disks are based on certain assumptions. One of the crucial assumptions is the free rotation of the disk. However, the free rotation of the disk is practically difficult. In practice, it is feasible to rotate the disk by shrink-fitting it over a solid cylindrical mandrel. In view of this, a design of a disk-mandrel assembly for achieving rotational autofrettage in disks is proposed in this article. The main aim of the design is to obtain appropriate values of the disk-mandrel interference and the rotational speed of the assembly to prevent the loss of contact of the disk with the mandrel during rotation. The critical speeds corresponding to the yield onset, contact separation and the full plastic deformation of the disk are obtained as a function of shrink interference. The safe operating design parameters can be decided by plotting the critical speeds with varying interference values. A detailed stress analysis during elastic-plastic loading of the assembly followed by the analysis of residual stresses in the assembly after unloading is presented. The analysis is based on the plane stress assumption, Tresca yield criterion and elastic unloading. The analysis is validated with a finite element method model in ABAQUS. The proposed design is illustrated through the numerical example of an ASTM A723 disk-mandrel assembly to achieve rotational autofrettage in the disk. With a small overstrain level of 17.5% in the disk, a large magnitude of compressive residual stress, viz., 0.52 times the yield stress, is induced.

Experimental Investigations on Temperature Generation and Release of Ultra-High Performance Concrete during Fatigue Tests

Smarter, more filigree, and resource-saving buildings are the aim of developments in the construction industry. In reinforced concrete construction, ultra-high strength concretes have been developed to achieve these goals. Due to their use and requirements, these highly pressure-resistant materials are increasingly exposed to cyclically occurring and high-frequency loads. Examples of this are applications in long-span bridges or wind turbines. Research into the fatigue behaviour of the new construction material is therefore very important for the standardization and practical introduction of the high performance material. In this article, we want to investigate the heating process of ultra-high performance concrete (UHPC) under fatigue stress in more detail. In previous investigations in this project, an influence of the heating on the fatigue strength could be determined. A systematic parameter study has defined decisive load configurations for a maximum heating process. The aim is now to better understand the heating process. For this purpose, the temperature generation rate and the temperature release, which probably influences the overall temperature development, are investigated. A test program with eight experiments gives information about the temperature release during the experiment and the heating rate with and without pre-damage in the sample. In addition, the causes of failure caused by temperature are investigated with additional insulated tests. The results are presented, discussed, and conclusions are drawn in the article. For instance, fatigue damage affects the rate of temperature increase, but not the thermal conductivity of the material. In the different configurations, the test specimens essentially overlap at the maximum temperature reached in the inner test specimen. In addition to the assumed influence of the temperature gradients in the cross section as a cause of premature failure due to additional constraint stresses, the maximum temperature in particular turns out to be decisive, independent of the gradient.

Multiphase Interleaved Bidirectional DC/DC Converter With Coupled Inductor for Electrified-Vehicle Applications

A nonisolated high-power-density bidirectional dc/dc converter named multiphase interleaved with a coupled inductor is described. The proposed converter allows low current and voltage ripple, lower power losses, reduction on power component stress, and magnetic volume. Moreover, the coupled inductor is applied to achieve current sharing between each leg in a simple manner, which is helpful to simplify the structure and meaningfully improve performance. Auxiliary clamp circuits are not required and can operate over a wide voltage and power range, achieve a better dynamic response and low ripple while maintaining high efficiency. This article illustrates the steady-state operating principle under the inductor current continuous, discontinuous conduction modes and their boundary conditions in detail, the voltage and current stress of the power devices are shown, parameter design guideline, mathematical derivations, and a comparison between the proposed converter and previous dc/dc converters were conducted. Finally, a 4.5-kW proof-of-concept laboratory prototype has been designed, developed, and tested to demonstrate the performance of the proposed converter for wide load variation. The measured efficiency for the rated load was over 98% for maximum input voltage. This article is accompanied by a video file demonstrating the operation of the converter.

Design, Fabrication, and Test of a 12 T REBCO Insert for a 27 T All-Superconducting Magnet

The higher magnetic field is an everlasting goal for researchers in the field of high-field superconducting magnets, for its vital significance to modern science and technology. After achieving our goal of 25 T superconducting magnet project, we set a more ambitious goal to obtain a central field of 27 T, by upgrading the previous 10 T REBCO (REBa2Cu3Ox, RE = rare earth) insert to 12 T. On the basis of the previous 10 T REBCO insert, the newly designed 12 T REBCO insert has an outer REBCO coil, which has the inner and outer diameters of 125 and 150 mm, respectively, and a height of 85 mm. The current grading method and the detailed stress analysis were employed in the design of the added REBCO coil. Stress analysis showed that the maximum hoop stress was reduced from 470 to 438 MPa after employing winding tension, overbanding, and cooldown. The designed highest engineering current density in this added REBCO coil is 383 A/mm2, much higher compared with the previous REBCO insert, the highest of which is only around 300 A/mm2. The rough operation margin for the previous REBCO coil and the added REBCO coil is 42.6% and 43.7%, respectively. This article mainly introduces the design, fabrication, and test results of the 27 T all-superconducting magnet in detail.

Using finite element analyses to assess the effect of a thickness gradient on the stress profile at the epoxy/silicone interface of thin coatings subjected to pull-off loading

Silicone-based materials can be applied on ship hulls to serve as foul release coatings. Depending on the application, coatings are not likely to have a uniform thickness. Pull-off tests of epoxy studs from silicone coatings with a thickness gradient found that for the thickest coatings, release initiated at the edge and proceeded inward with no bias in the peeling direction, and as the thickness decreased the release initiated on the thin side of the coating. Release mechanism and critical pull-off force were also affected. In this work, finite element models were developed to predict the detailed stress field at the silicone/epoxy interface in silicone coatings with a thickness gradient. Average coating thickness, thickness gradient, and Poisson's ratio were varied to determine changes in the value and location of the peak interface stress and determine the properties that produce the highest peak interface stress, which should correspond to the lowest critical pull-off force. While the peak stress increased with increasing thickness gradients in all cases, the optimal geometric properties depended on the Poisson's ratio of the coating, so the specific material chosen is an important factor. The location of the peak stress was nearly always on the thin side of the coating when a thickness gradient was present, although the exact location (i.e., edge or interior) also depended on the Poisson's ratio.

Cold stiffening of orthotropic steel decks by a composite UHPFRC layer

Cold stiffening of the plate of Orthotropic Steel Deck (OSD) of bridges can be achieved by adding a layer of Ultra-High Performance Fiber Reinforced Cementitious Composite material (UHPFRC) on top of the deck plate by composite design, thus expecting to reduce stresses in fatigue critical details of OSD and avoid fatigue vulnerable welded details at composite interface. This paper focuses on experimental and analytical study for the bending behavior of UHPFRC – steel composite specimens in elastic domain, corresponding to the stress levels of deck plate for in-service steel bridge with OSD. In the total 11 UHPFRC – steel composite test specimens, it was considered UHPFRC with thicknesses ranging from 25 mm to 50 mm, loading configurations simulating sagging or hogging moment region, and different composite designs including materials natural bonding, epoxy-glued interface and epoxy-glued corrugated steel plate shear connector. Epoxy-glued interface was effective composite method leading to stiffness improvement for sagging moment region of OSD and thus decreased stresses in the OSD deck plate. The proposed corrugated steel plate shear connector turned out to be effective for stiffness improvement especially for specimens simulating hogging moment region, indicating that this mechanical connector acted as both shear connector and confined steel bar. The bending processes were analyzed for UHPFRC – steel composite specimens simulating sagging and hogging moment region respectively, especially for the loading stage before attaining 0.5εsy at mid-span section. Based on test and analytical results, design recommendations were given for OSD stiffening by means of UHPFRC.

Mathematical analysis of influence of ultrasonic stabilization of residual stresses in round plate details

The most important task of precision engineering at the present stage is the development of more efficient technological processes for manufacturing parts that ensure not only high accuracy at a minimum cost, but also the preservation of the original accuracy indicators throughout the entire service life of the product. (Research purpose) The research purpose is in studying the technological operation of stabilization of residual stresses of a round plate based on the method of relaxation of residual stresses by the influence of oscillatory movements of ultrasonic frequency. (Materials and methods) The article notes that the parts and components of the sensors are connected to each other, mainly by means of screws and other threaded connections; the abundance of springs (of return type), internal backlashes of mobile mechanisms, contributes to the occurrence of residual stresses (shrinkage, lapping), which affects the stability of the readings. Authors proposed a method and performed mathematical modeling of ultrasonic stabilization of the deformation of a round plate (elastic sensing element), having previously provided tension by the influence of an external load on its surface. Authors have found that this technology provides high performance and is not difficult to implement from a technical point of view. (Results and discussion) It was found by mathematical analysis that the processing time depends inversely on the vibration frequency of the plate, so processing the plate with an ultrasonic frequency significantly reduces the required processing time, increases its performance compared to traditional methods of training. (Сonclusions) With a small amplitude of these vibrations, the energy of a single oscillation cycle decreases, and this significantly reduces the amount of accumulated deformation, which improves the quality of processing.

Detailed stress analysis of a twill orthogonally woven textile composite

A finite element analysis framework that leverages high-performance computing was used to analyze a twill orthogonally woven textile model. Boundary conditions for uniaxial tension along the warp direction were applied to a large analysis region, and an interior subregion was used for investigating the stress distributions. The locations of severe stresses were investigated for the binders, wefts, warps, and matrix, respectively, and the connection of the stress state to the surrounding tow architecture was discussed. It was shown that the highest stresses developed in the binders where the path of a binder changed direction, due to a transfer of load to nearby wefts that induced a severe shear stress in the binder. Additionally, severe stress concentrations were observed in both the wefts and binders where the binders traversed the thickness of the textile and came near a weft. The magnitude of the concentration in the binders closely matched across similar locations. On the other hand, the concentrations in the weft appeared to be sensitive to the faceted surfaces of the tows, which sometimes resulted in sharp edges, but these stress the concentrations in the wefts did remain localized. In the warps, the normal stress in the direction of the load was the largest, but the most severe stress state was shown to occur in a very small region where warps came close to binders as the path of the binder transitioned.

Shortcut Method for Pipe Expansion Loop Sizing

Abstract In the engineering practice, it is often necessary to define supporting scheme and expansion loop requirements for piping distribution systems in very early phases of a project. While placing pipe supports is a relatively easy and straightforward task, providing accurate loop locations and dimensions for hot piping systems can often be challenging. In the early phases of any project, it is impractical, costly and time consuming to perform detailed stress analysis of a piping system to provide expansion loop dimensions, and therefore approximate methods are often used. Comprehensive overview of these existing procedures most commonly used in the engineering practice is given in this article. However, the fact is that most of the existing methods are based on the inconvenient charts and tables with scarce background data. Procedure proposed in this article is based on over 150 expansion loop models and provides a simple and accurate analytical method to size and verify piping loops. Two fully worked examples show the simplicity and accuracy of the proposed model and its advantages over the methods typically used in the engineering practice.

Geodynamic subduction models constrained by deep earthquakes beneath the Japan Sea and eastern China

Details of Pacific plate subduction under the Japan Sea and associated current seismicity remain challenging. Seismic tomography reveals a continuous slab dipping at ~30° down to ~600 km, and earthquake mechanisms point to down-dip compression. Further, the slab is lying at the 660-km discontinuity, and this zone is aseismic. We suggest that this pattern results from the slab’s negative thermal buoyancy, resistance of the viscous lower mantle, and buoyancy forces associated with the phase transitions at 410 km and 660 km. Our model comprises an ageing subducting plate, nonlinear rheology and major phase transitions. The model explains the observed low dip angle of the slab and predicts a detailed stress pattern related to bending down to 450 km, followed by unbending as the slab is laid flat upon the 660 km boundary. Remarkably, in the bending/unbending regions, down-dip compression occurs close to the slab top/bottom, respectively. As only down-dip compression is observed, we argue that the earthquakes are mapping the top and bottom of the slab. The absence of seismicity in the flat-lying slab is explained by significantly lower stresses and higher temperatures. With this new knowledge, increasingly accurate seismic locations will considerably improve images of finite-extent slab geometry.

Investigation of exact analytical solutions for circular notched composite laminates under tensile loading

For the design of composite structures with circular cut-outs analytical, experimental and numerical methods are available. This paper investigates numerous exact analytical methods introduced in literature as an example of the Airbus Industries Test Method for determination of open hole tensile strength, conforming to AITM 1-0007. Experimental testing accompanied by digital image correlation of unidirectional 0° and 90° laminates as well as quasi-isotropic CFRP laminates with width-to-diameter (w/d) ratios of 3 and 5 is conducted. In addition, 3D finite element models of the test specimens are created for detailed analysis on lamina level. A preliminary study on numerous analytical methods introduced in literature shows that application of any of those methods results in one of two possible stress distributions. A qualitative comparison of 2D strain fields on laminate level reveals the high prediction quality of the analytical solutions. Furthermore, a detailed stress analysis on lamina level by comparison to a validated FE model is conducted. The results show that exact analytical solutions exhibit a satisfactory stress prediction quality for w/d ratios as low as 3 and thus can be recommended for preliminary design purposes.

Failure Analysis of Unidirectional Ceramic Matrix Composite Lamina and Cross-Ply Laminate under Fiber Direction Uniaxial Tensile Load: Cohesive Zone Modeling and Brittle Fracture Mechanics Approach

The current research work presents the computational micromechanical analysis of the room temperature tensile failure behavior of unidirectional (UD) and cross-ply (0/90) ceramic matrix composites (CMCs). For computational micromechanical analysis, three-dimensional (3D) representative volume element (RVE) and multi-fiber multilayer RVE (M2 RVE) models are generated that are representative of the lamina and the laminate under investigation. The RVE and M2 RVE models are generated by replicating the fiber distribution, and the placement of the fibers observed in a microscopic image of an actual CMC laminate. The generated RVE models consist of the discrete representation of individual constituent phases of the CMC such as fibers, interphase, matrix, and the fiber–interphase interface region. Under the applied external tensile load, the fiber–interphase interface interactions are modeled using the cohesive elements that follow the bilinear traction separation law. The matrix, fiber, and interphase materials failure behavior is captured using a brittle cracking model. In order to validate the proposed numerical methodology, the predicted average stress–strain curve at the UD laminate level is compared to the experimental stress–strain curve reported in the literature. In addition, the observed different phases in the predicted stress–strain curve are validated with the literature data. Using the proposed numerical methodology, a detailed local stress–strain and damage analysis leads to an observation that the so-called ductile stress–strain behavior (kink in the stress–strain curve) of a CMC UD laminate under uniaxial fiber direction tensile loads is mainly caused by the matrix damage initiation. Apart from the SiC material properties such as strength and fracture energy, it is also observed that the RVE size influences the average strength and failure strain predictions using computational micromechanics.

Comparative time-course transcriptome analysis in contrasting Carex rigescens genotypes in response to high environmental salinity.

Soil salinization is one of most crucial environmental problems around the world and negatively affects plant growth and production. Carex rigescens is a turfgrass with favorable stress tolerance and great application prospect in salinity soil remediation and utilization; however, the molecular mechanisms behind its salt stress response are unknown. We performed a time-course transcriptome analysis between salt tolerant 'Huanghua' (HH) and salt sensitive 'Beijing' (BJ) genotypes. Physiological changes within 24h were observed, with the HH genotype exhibiting increased salt tolerance compared to BJ. 5764 and 10752 differentially expressed genes were approved by transcriptome in BJ and HH genotype, respectively, and dynamic analysis showed a discrepant profile between two genotypes. In the BJ genotype, genes related to carbohydrate metabolism and stress response were more active and ABA signal transduction pathway might play a more important role in salt stress tolerance than in HH genotype. In the HH genotype, unique increases in the regulatory network of transcription factors, hormone signal transduction, and oxidation-reduction processes were observed. Moreover, trehalose and pectin biosynthesis and chitin catabolic related genes were specifically involved in the HH genotype, which may have contributed to salt tolerance. Moreover, some candidate genes like mannan endo-1,4-beta-mannosidase and EG45-like domain-containing protein are highlighted for future research about salt stress resistance in C. rigescens and other plant species. Our study revealed unique salt adaptation and resistance characteristics of two C. rigescens genotypes and these findings could help to enrich the currently available knowledge and clarify the detailed salt stress regulatory mechanisms in C. rigescens and other plants.

A boundary-condition-transfer method for shell-to-solid submodeling and its application in high-speed trains

The boundary-condition-transfer method for a shell-to-solid submodeling is fundamental for analyzing local or weak regions of a complex structure accurately. In this paper, a novel method is presented for transferring displacement boundaries based on hypothetical nodes. By considering the invariable volume of an element as a constraint, the interpolation through conventional methods using 6-degrees-of-freedom (DOFs) nodal translations and rotations is converted into a 3-DOF translational interpolation at the cut boundary of a submodel. To demonstrate this method, a radial basis function (RBF) was employed for interpolation. For validating the accuracy of the proposed method, a square plate with a hole under tensile and bending load were designed as examples. By considering global and local errors, three typical kernel functions with respect to mesh density ratios were analyzed to fix the optimal parameter in RBF. The examples showed that the proposed method significantly improves the accuracy in shell-to-solid submodeling problems compared to conventional solutions such as ANSYS. For structural analysis of a high-speed train car body under combined mechanical and aerodynamic loads, the submodeling method was implemented on the solid-element-based local model with a welding seam, with which a more detailed stress state was obtained compared with that computed by shell elements. The accurate and reliable results illustrate that the proposed method is the core for the global–local analysis of large complex structures, which also is used for the design and evaluation of the mechanical properties.