Theory and practice for assessing structural integrity and dynamical integrity of high-speed trains

Purpose–The safety and reliability of high-speed trains rely on the structural integrity of their components and the dynamic performance of the entire vehicle system.This paper aims to define and substantiate the assessment of the structural integrity and dynamical integrity of high-speed trains in both theory and practice.The key principles and approacheswill be proposed,and their applications to high-speed trains in Chinawill be presented.Design/methodology/approach–First,the structural integrity and dynamical integrity of high-speed trains are defined,and their relationship is introduced.Then,the principles for assessing the structural integrity of structural and dynamical components are presented and practical examples of gearboxes and dampers are provided.Finally,the principles and approaches for assessing the dynamical integrity of highspeed trains are presented and a novel operational assessment method is further presented.Findings–Vehicle system dynamics is the core of the proposed framework that provides the loads and vibrations on train components and the dynamic performance of the entire vehicle system.For assessing the structural integrity of structural components,an open-loop analysis considering both normal and abnormal vehicle conditions is needed.For assessing the structural integrity of dynamical components,a closed-loop analysis involving the influence of wear and degradation on vehicle system dynamics is needed.The analysis of vehicle system dynamics should follow the principles of complete objects,conditions and indices.Numerical,experimental and operational approaches should be combined to achieve effective assessments.Originality/value–The practical applications demonstrate that assessing the structural integrity and dynamical integrity of high-speed trains can support better control of critical defects,better lifespan management of train components and better maintenance decision-making for high-speed trains.

The hydraulic performance and structural integrity of A-Jack armour layer

A-Jacks are concrete armor units that are used in both open channel and coastal applications.In open channel applications,they are used for bank and toe protection,flow and grade control,bridge pier scour protection,energy dissipation,and habitat.These small units may be fabricated in standard block machines.In coastal applications,A-Jacks are used in breakwaters,jetties,revetments,and habitat development.Coastal units are generally much larger and more robust than the small open channel units.This paper focuses on coastal applications and in particular,combines results on three topics:(1)recent hydraulic model studies,(2)alternative fabrication methods,and(3)bundle placement construction methods.Hydraulic models studies were conducted that examined the standard random and uniform placement methods,and also the bundle placement method.In bundle placement,3~20 A-Jacks are banded together,lifted with a spreader bar,and placed as a single crane pick.This significantly decreases installation time during construction.It also provides a more hydraulically stable placement technique.The hydraulic model tests examined the bundle stability in random waves for cases where the binding remains in tack and is removed.The geometry of A-Jacks enables a variety of fabrication techniques.One option is to fabricate the A-Jacks as two pieces using flat forms and then grout the two pieces together.Flat forms may be used in conventional block machines for A-Jacks sizes up to 1.3 m.Larger sizes may be wet cast in flat forms or gang forms.The A-Jacks geometry has been recently modified to increase grouting efficient and strength.Large A- Jacks may also be cast in a single piece using 'clam shell' type forms.

Structural Integrity Analysis of Containers Lost at Sea Using Finite Element Method

Unlike traditional transportation,container transportation is a relatively new logistics transportation mode.Shipping containers lost at sea have raised safety concerns.In this study,finite element analysis of containers subjected to hydrostatic pressure,using commercial software ANSYS APDL was performed.A computer model that can reasonably predict the state of an ISO cargo shipping container was developed.The von Mises stress distribution of the container was determined and the yield strength was adopted as the failure criterion.Numerical investigations showed that the conventional ship container cannot withstand hydrostatic pressure in deep water conditions.A strengthened container option was considered for the container to retain its structural integrity in water conditions.

An emerging role of arecoline on growth performance,intestinal digestion and absorption capacities and intestinal structural integrity of adult grass carp(Ctenopharyngodon idella)

Arecoline is an alkaloid with important pharmacological effects in the plant areca nut,which has been demonstrated to be an agonist of muscarinic receptors(M receptor).This study explored the influences of dietary arecoline on growth performance,intestinal digestion and absorption abilities,antioxidant capacity,and the apical junction complex(AJC)of adult grass carp(Ctenopharyngodon idella).Adult grass carp(608to 1512 g)were fed at 6 graded levels of dietary arecoline(0,0.5,1.0,1.5,2.0,and 2.5 mg/kg diet)for 9weeks.The results suggested that appropriate dietary supplementation of arecoline(1.0 mg/kg)increased growth parameters and intestinal growth in adult grass carp(P<0.05),enhanced digestion and absorption capacities(P<0.05),up-regulated muscarinic receptor 3(M3)mRNA level(P<0.05),increased the content of neuropeptide fish substance P(P<0.05),improved antioxidant capacity by activating the Keap1a/Nrf2signaling pathway(P<0.05),reduced intestinal mucosal permeability(P<0.05),and increased m RNA levels of tight junction(TJ)and adherent junction AJ-related proteins in fish by inhibiting the RhoA/ROCK signaling pathway(RhoA/ROCK/MLCK/NMII)(P<0.05).In addition,the appropriate arecoline supplementation for adult grass carp was determined to be 1.20,1.21,1.07,and 1.19 mg/kg based on percentage weight gain,lipase activity,serum diamine oxidase,and protein carbonyl,respectively.Overall,to the best of our knowledge,we investigated for the first time the effects and possible mechanisms of dietary arecoline on intestinal digestive and absorptive capacities and structural integrity in fish and evaluated the appropriate level of supplementation.

Recent, development in low-constraint fracture toughness testing for structural integrity assessment of pipelines

Fracture toughness measurement is an integral part of structural integrity assessment of pipelines. Traditionally, a single-edge-notched bend （SE（B）） specimen with a deep crack is recommended in many existing pipeline structural integrity assessment procedures. Such a test provides high constraint and therefore conservative fracture toughness results. However, for girth welds in service, defects are usually subjected to primarily tensile loading where the constraint is usually much lower than in the three-point bend case. Moreover, there is increasing use of strain-based design of pipelines that allows applied strains above yield. Low-constraint toughness tests represent more realistic loading conditions for girth weld defects, and the corresponding increased toughness can minimize unnecessary conservatism in assessments. In this review, we present recent developments in low-constraint fracture toughness testing, specifically using single-edge- notched tension specimens, SENT or SE（T）. We focus our review on the test procedure development and automation, round-robin test results and some common concerns such as the effect of crack tip, crack size monitoring techniques, and testing at low temperatures. Examples are also given of the integration of fracture toughness data from SE（T） tests into structural integrity assessment.

STRUCTURAL INTEGRITY

A stronger city is emerging from the ruins of Tangshan.But can it handle another major earthquake? Every time he passes the spot where his younger sister is bunied,

Structural integrity and damage of ZrB_(2) ceramics after 4 MeV Au ions irradiation

Ultra-high temperature ceramics have been considered as good candidates for plasma facing materials due to their combination of high melting point,high strength and hardness,high thermal conductivity as well as good chemical inertness.In this study,zirconium diboride has been chosen to investigate its irradiation damage behavior.Irradiated by 4 MeV Au^(2+)with a total fluence of 2.5×10^(16)cm^(-2),zirconium diboride ceramic shows substantial resilience to irradiation-induced damage with its structural integrity well maintained but mild damage at lattice level.Grazing incident X-ray diffraction evidences no change of the hexagonal structure in the irradiated region but its lattice parameter a increased and c decreased,giving a volume shrinkage of 0.46%.Density functional theory calculation shows that such lattice shrinkage corresponds to a non-stoichiometric compound as ZrB1.97.Electron energy-loss spectroscopy in a transmission electron microscope revealed an increase of valence electrons in zirconium,suggesting boron vacancies were indeed developed by the irradiation.Alo ng the irradiation depth,long dislocations were observed inside top layer with a depth of 750 nm where the implanted Au ions reached the peak concentration.Underneath the top layer,a high density of Frank dislocations is formed by the cascade collision down to a depth of 1150 nm.All the features show the potential of ZrB_(2) to be used as structural material in nuclear system.

Structural health monitoring of bridges in the State of Connecticut

A joint effort between the Connecticut Department of Transportation and the University of Connecticut has been underway for more than 20 years to utilize various structural monitoring approaches to assess different bridges in Connecticut. This has been done to determine the performance of existing bridges, refine techniques needed to evaluate different bridge components, and develop approaches that can be used to provide a continuous status of a bridge＇s structural integrity. This paper briefly introduces the background of these studies, with emphasis on recent research and the development of structural health monitoring concepts. This paper presents the results from three different bridge types： a post-tensioned curved concrete box girder bridge, a curved steel box-girder bridge, and a steel multi-girder bridge. The structural health monitoring approaches to be discussed have been successfully tested using field data collected during multi-year monitoring periods, and are based on vibrations, rotations and strains. The goal has been to develop cost-effective strategies to provide critical information needed to manage the State of Connecticut＇s bridge infrastructure.

Integrity Analysis on Existing Crane Runway Girders with Defects Using Constraint-Based R6 Criterion

In order to resolve the safety problem of the existing crane runway gir-ders(CRGs)with defects,the constraint-based R6 criterion is proposed to assess their structural integrity.The ex isting steel CRGs with defects at the weld joint between the upper flange and web plate,are characterized to three-dimensional finite element models with a semi-ellipse surface crack.The R6 criterion has been modified by considering the constraint effect which is represented by T-stress.The analysis results ilustrate that working condition of the cracked CRGs leads to high constraint level along the crack front.The crack aspect ratio(a/c)and run-way eccentricity(e)have significant influence on the integrity of the cracked CRGs.The integrity assessment results based on modified constraint-based R6 failure criterion enable to more effectively protect the cracked CRGs from brittle fracture failure.

Structural modeling of proteins by integrating small-angle x-ray scattering data

Elucidating the structure of large biomolecules such as multi-domain proteins or protein complexes is challenging due to their high flexibility in solution. Recently, an ＂integrative structural biology＂ approach has been proposed, which aims to determine the protein structure and characterize protein flexibility by combining complementary high- and lowresolution experimental data using computer simulations. Small-angle x-ray scattering（SAXS） is an efficient technique that can yield low-resolution structural information, including protein size and shape. Here, we review computational methods that integrate SAXS with other experimental datasets for structural modeling. Finally, we provide a case study of determination of the structure of a protein complex formed between the tandem SH3 domains in c-Cb1-associated protein and the proline-rich loop in human vinculin.

Pulsed Eddy Current Non-destructive Testing and Evaluation:A Review

Pulsed eddy current （PEC） non-destructive test- ing and evaluation （NDT＆E） has been around for some time and it is still attracting extensive attention from researchers around the globe, which can be witnessed through the reports reviewed in this paper. Thanks to its richness of spectral components, various applications of this technique have been proposed and reported in the lit- erature covering both structural integrity inspection and material characterization in various industrial sectors. To support its development and for better understanding of the phenomena around the transient induced eddy currents, attempts for its modelling both analytically and numeri- cally have been made by researchers around the world. This review is an attempt to capture the state-of-the-art development and applications of PEC, especially in the last 15 years and it is not intended to be exhaustive. Future challenges and opportunities for PEC NDT＆E are also presented.

Improving the damage potential of W-Zr reactive structure material under extreme loading condition

Projectiles made of reactive structure materials(RSM)can damage the target with not only kinetic but also chemical energy,but the enhanced damage potential of RSM may become compromised if extreme loading condition disintegrates the projectile before the target is reached.In this work,a ductile coating of Ni was introduced to a tungsten-zirconium(W-Zr)alloy,a typical brittle RSM,to preserve the damage potential of the projectile.Detonation driving tests were carried out with X-ray photography and gunpowder deflagration driving tests were carried out with high-speed photography for the coated and uncoated RSM samples,respectively.The craters on the witness target were analyzed by scanning electron microscopy and X-ray diffraction.The Ni coating was found to effectively preserve the damage potential of the W-Zr alloy under extreme loading conditions,whereas the uncoated sample fractured and ignited before impacting the target in both detonation and deflagration driving.The crack propagation between the reactively brittle core and the ductile coating was analyzed based on the crack arrest theory to mechanistically demonstrate how the coating improves the structural integrity and preserves the damage potential of the projectile.Specifically,the Ni coating envelops theW-Zr core until the coated sphere penetrates the target,and the coating is then eroded and worn to release the reactive core for the projectile to damage the target more intensively.

人工智能辅助下的海上风力支撑结构延寿评估研究综述

The primary objective of the present literature review is to provide a constructive and systematical discussion based on the relevant development,unsolved issues,gaps,and misconceptions in the literature regarding the fields of study that are building blocks of artificial intelligence-aided life extension assessment for offshore wind turbine support structures.The present review aims to set up the needed guidelines to develop a multi-disciplinary framework for life extension management and certification of the support structures for offshore wind turbines using artificial intelligence.The main focus of the literature review centres around the intelligent risk-based life extension management of offshore wind turbine support structures.In this regard,big data analytics,advanced signal processing techniques,supervised and unsupervised machine learning methods are discussed within the structural health monitoring and condition-based maintenance planning,the development of digital twins.Furthermore,the present review discusses the critical failure mechanisms affecting the structural condition,such as high-cycle fatigue,low-cycle fatigue,fracture,ultimate strength,and corrosion,considering deterministic and probabilistic approaches.

Approach for Obtaining Material Mechanical Properties in Local Region of Structure Based on Accurate Analysis of Micro-indentation Test

The hot or cold processing would induce the change and the inhomogeneous of the material mechanical properties in the local processing region of the structure,and it is difficult to obtain the specific mechanical properties in these regions by using the traditional material tensile test.To accurately get actual material mechanical properties in the local region of structure,a micro-indentation test system incorporated by an electronic universal material test device has been established.An indenter displacement sensor and a group of special micro-indenter assemblies are estab-lished.A numerical indentation inversion analysis method by using ABAQUS software is also proposed in this study.Based on the above test system and analysis platform,an approach to obtaining material mechanical properties in the local region of structures is proposed and established.The ball indentation test is performed and combined with the energy method by using various changed mechanical properties of 316L austenitic stainless steel under differ-ent elongations.The investigated results indicate that the material mechanical properties and the micro-indentation morphological changes have evidently relevance.Compared with the tensile test results,the deviations of material mechanical parameters,such as hardness H,the hardening exponent n,the yield strength σy and others are within 5%obtained through the indentation test and the finite element analysis.It provides an effective and convenient method for obtaining the actual material mechanical properties in the local processing region of the structure.

Three-Layer Structured SnO_(2)@C@TiO_(2)Hollow Spheres for High-Performance Sodium Storage

The unsatisfactory conductivity and large volume variation severely handicap the application of SnO_(2)in sodium-ion batteries(SIBs).Herein,we design unique three-layer structured SnO_(2)@C@TiO_(2)hollow spheres to tackle the above-mentioned issues.The hollow cavity affords empty space to accommodate the volume variation of SnO_(2),while the C and TiO_(2)protecting shells strengthen the structural integrity and enhances the electrical conductivity.As a result,the three-layer structured SnO_(2)@C@TiO_(2)hollow spheres demonstrate enhanced Na storage performances.The SnO_(2)@C@TiO_(2)manifests a reversible capacity two times to that of pristine SnO_(2)hollow spheres.In addition,Ex situ XRD reveals highly reversible alloying and conversion reactions in SnO_(2)@C@TiO_(2)hollow spheres.This study suggests the introduction of a hollow cavity and robust protecting shells is a promising strategy for constructing SIB anode materials.

APPLICATION OF SINTAP TO THE SAFETY ASSESSMENT OF X65 PIPELINE STEEL

The recently developed European flaw assessment procedure, structural integrity assessment procedure（SiNTAP） is applied to assessment for welded joints of the API 5L X65 pipeline steel with an assumed embedded flaw and surface flaw at the weld toe. As one of the basic input data, fracture toughness crack tip opening displacement （CTOD） tests are conducted at 0℃ and performed according to the requirements of the standard of BS7448. For the heat affected zone （HAZ） specimens, the microstructure observation is performed to insure that the tip of the crack is located in the coarse grain zone. The result explains the dispersity of the test values. In structural integrity assessment procedure-fracture assessment diagram（SINTAP FAD） method, the failure curves of welded joints at level 1 and 3 are derived from the tensile test results. The results of the assessment show that all assessment points are located within the failure lines of analysis level 1 and 3. So the welded joint of the pipeline is safe. This study laid the foundation of application of SINTAP to pipeline structure assessment.

Stability of M13 Phage in Organic Solvents

The effect of different types of organic solvents on the structural integrity of M13 phages has been directly visualized by transmission and scanning electron microscopy. The exposure of M13 phages to apolar hexane had no effect on the structure of the phages for up to 8 h. In contrast, phages showed ~10-fold contraction into rod-like I-forms and to flattened spheroids with ~12 nm diameter upon exposure to polar organic solvents. We show that this finding can be beneficial for the macromolecular self-assembly and in broader aspects, to enhance the spatial arrangement of desired inorganic nanoparticles in the rapidly developing field of virotronics.

Reducing structural degradation of high-voltage single-crystal Ni-rich cathode through in situ doping strategy

Polycrystalline Ni-rich layered oxide (Li Ni_(x)Co_(y)Mn_zO_(2)(NCM),x>0.8) cathode material with high specific capacity and low cost is considered as one of the most promising candidate materials for lithium-ion batteries (LIBs).However,it suffers from severe structural and capacity degradation during practical cycling,especially under harsh operation condition(ultrahigh cutoff voltage and elevated temperature,etc.).One promising approach to mitigate these issues is to develop a single-crystal Ni-rich NCM cathode,which could enhance structural integrity and improve capacity retention,due to its robust and stable micro-sized primary particles.However,the improved cyclic stability comes at the expense of reversible capacity and rate capability,owing to the relatively low Li^(+) diffusion efficiency for its micron-sized primary particles.Moreover,the structural degradation and exacerbation of interfacial reactions for the Ni-rich NCM cathode under highvoltage (≥4.5 V) would quickly trigger the poor electrochemical performance,limiting its practical applications.Herein,Li Ni_(0.827)Co_(0.11)Zr_(0.003)Mn_(0.06)O_(2)(Zr@SC-N_(83)) cathode material was successfully synthesized via the in situ doping strategy.It could not only effectively maintain the reversibility of phase transition between H2 and H3 after long-term cycling at high voltage (4.6 V),but also enhance lithium-ion diffusion,thus improving the cycling performance and good rate performance for the Zr@SC-N_(83)cathode.As a result,0.3 wt%Zrdoping cathode delivers an initial discharging capacity of 200.1 m Ah·g^(-1)at 1.0C and at the high cutoff voltage of 4.6 V,exhibiting the satisfactory capacity retention of 85.5%after 100cycles.It provides an effective route toward low-cost and higher energy density for lithium-ion batteries with Ni-rich cathode.

Full-Field Stress Analysis of Perforated Members from Aligned Single-Element Strain Gages

Engineering members often include cutouts.Although the structural integrity of such members can be highly influenced by associated stresses,determining them may be very challenging for finite shapes operating in an industrial environment.This is particularly so if the loading is not well known,a common occurrence in practical situations.While photomechanical methods can be effective,they necessitate optical access to the component,something which is also often unavailable.Recognizing the above,this paper demonstrates ability to determine the complete stresses throughout a perforated tensile plate using only aligned,single-element strain gages rather than multi-element rosettes.Although reliability is verified using finite elements,an objective of the technique is for situations when finite element methods are not feasible,e.g.,the loading is inadequately known.The approach is applicable to members fabricated from isotropic,orthotropic or functionally-graded materials and is not restricted to a particular shape,cutout arrangement or loading condition.

Analysis of vibration reduction characteristics and applicability of steel-spring floating-slab track

A coupled dynamics computation model for metro vehicles, along with a steel-spring floating-slab track, is developed based on the theory of vehicle-track coupled dynamics. Using the developed model, the influences of the thickness, length and mass of floating-slab, spring rate and its arrangement space, running speed, etc. on the time and frequency domain characteristics of steel-spring fulcrum force are analyzed. The applicability of steel-spring floatingslab track is discussed through two integrated example cases of metro and buildings possessing distinct natural vibra- tion characteristics. It is concluded that, it is quite significant, in the optimization modular design of the parameters of steel-spring floating-slab track, to take the matching relationship of both the amplitude-frequency characteristics of steel-spring fulcrum force and natural vibration characteristics of integrated structures into comprehensive consideration. In this way the expensive steel-spring floating-slab track can be economically and efficiently utilized according to the site condition, and at the same time, the economic losses and bad social impact resulted from the resonance during usage of steel-spring floating-slab track can be avoided.