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structural Durability & Health Monitoring 2025年第1期19卷 25-54页

作者： Chao Zhang Shang-Xi Lai Hua-Ping Wang School of Civil Engineering and mechanics Lanzhou UniversityLanzhou730000China Key Laboratory of Special Functional Materials and structural Design Ministry of EducationLanzhou UniversityLanzhou730000China

Modal parameters can accurately characterize the structural dynamic properties and assess the physical state of the ***,it is particularly signiﬁcant to identify the structural modal parameters according to the monitoring data information in the structural health monitoring(SHM)system,so as to provide a scientiﬁc basis for structural damage identiﬁcation and dynamic model modiﬁ*** view of this,this paper reviews methods for identifying structural modal parameters under environmental excitation and brieﬂy describes how to identify structural damages based on the derived modal *** paper primarily introduces data-driven modal parameter recognition methods(e.g.,time-domain,frequency-domain,and time-frequency-domain methods,etc.),brieﬂy describes damage identiﬁcation methods based on the variations of modal parameters(e.g.,natural frequency,modal shapes,and curvature modal shapes,etc.)and modal validation methods(e.g.,Stability Diagram and Modal Assurance Criterion,etc.).The current status of the application of artiﬁcial intelligence(AI)methods in the direction of modal parameter recognition and damage identiﬁcation is further *** on the pre-vious analysis,the main development trends of structural modal parameter recognition and damage identiﬁcation methods are given to provide scientiﬁc references for the optimized design and functional upgrading of SHM systems.

关键词： structural health monitoring data information modal parameters damage identiﬁcation AI method

3-D Numerical Simulation on the Chip Machining Process of a Metal Block

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上海交通大学学报 2004年第z2期38卷 108-113页

作者： Yan Yixia Yin Yihui Li Weifen Institute of Southwest structural mechanics Mianyang621900 China Institute of Southwest Structural Mechanics Mianyang621900 China Institute of Southwest Structural Mechanics Mianyang621900 China

In this paper, the cutting process of a metal block is numerically simulated by the dynamic explicit FE code ABAQUS. Taking thermo-mechanical coupling effect into consideration, the simulation presents the variation of temperature, stress and strain distribution in the workpiece and chip. The effective plastic strain failure criterion is applied to modeling the chip separation and plastic formation. And the phenomenon of the contact and friction between the workpiece and the cutting tool are described in the paper.

关键词： cutting 3-D FEM thermo-mechanical coupling

Engineering vibration monitoring by GPS:long duration records

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Earthquake Engineering and Engineering Vibration 2009年第3期8卷 459-467页

作者： F.Casciati C.Fuggini Department of structural mechanics University of PaviaItaly

Monitoring the performance of any structure requires real-time measurements of the change of position of critical points. Different techniques can be used for this purpose, each one offering advantages and disadvantages. The technique based on satellite positioning systems （GPS, GLONASS and the future GALILEO） seems to be very promising at least for long period structures. The GPS in particular provides sampling rates that are able to track dynamic displacements with high accuracy. Its service ability is independent of atmospheric conditions, temperature variations and visibility of the monitored object. This paper investigates the reliability and accuracy of the measurements of dual frequency GPS receivers. A linear electromagnetic motor moves an object along a given direction. The changes of position are compared witb their estimates as recorded by a GPS receiver, whose antenna is located on the reference object. The comparison is based on sufficiently long records.

关键词： infrastructure monitoring global positioning system (GPS) delay positioning errors multi-path error signal geometric dilution of precision linear motor amplitudes power spectral densities

INFLUENCE OF INTERNAL HYDROGEN ON THE HYDROGENEMBRITTLEMENT OF AUSTENITIC STAINLESS STEEL

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Acta Metallurgica Sinica(English Letters) 1997年第3期10卷 228-232页

作者： Y Tan D.H Zhouand J. Feng (Institute of structural mechanics, Chengdu 610003, China) Inst of structural mechanics Chengdu China

The HE (hydrogen embrittlement) behavior of two kinds of austenitic stee Cr21Ni6Mn9 and 1Cr18Ni9Ti is reprted in this paper. The factors (temperc-ture/strain rate/stress concentration coefficient and purity of hydrogen) are restricted to the severe conditions under which HE is easy to occur. The concentmtion of in-ternal hydrogen in samples is changed by varying the time during which samples are placed in 24 MPa hydrogen at 473 K Then the tensile properties of the samples are tested. The results indicate that the degree of the hydrogen-induced plastic loss (L)of Cr21Ni6Mn9 is different with the internal hydrogen(CH). Howeven even when CH is as high as 70 PPm L is 15% and the fracture may be explained as a larpe amount of internal hydrogen hinders the cross-slip of dislocations when the steel is *** the metastable steel 1Cr18Ni9Ti the hydrogen-induced plastic loss is severer than that of Cr21Ni6Mn9. When CH is 40 PPm its L is as high as 42%. The mechanism may be explained as a larpe amount of hyderpen decreases the stacking fault enerpy and brittle ε-phase is produed in the high CH areas.

关键词： austenitic stainless steel internal hydrogen hydrogen embrittlement hydrogen-induced ductility loss

Molecular dynamics investigation of mechanical properties of single-layer phagraphene

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Frontiers of structural and Civil Engineering 2019年第2期13卷 495-503页

作者： Ali Hossein Nezhad SHIRAZI Institute of structural mechanics Bauhaus-Universitat WeimarWeimarGermany

Phagraphene is a very attractive two-dimensional (2D) full carbon allotrope with very interesting mechanical, electronic, optical, and thermal properties. The objective of this study is to investigate the mechanical properties of this new graphene like 2D material. In this work, mechanical properties of phagraphene have been studied not only in the defect-free form, but also with the critical defect of line cracks, using the classical molecular dynamics simulations. Our study shows that the pristine phagraphene in zigzag direction experience a ductile behavior under uniaxial tensile loading and the nanosheet in this direction are less sensitive to temperature changes as compared to the armchair direction. We studied different crack lengths to explore the in fluence of defects on the mechanical properties of phagraphene. We also investigated the temperature effect on the mechanical properties of pristine and defective phagraphene. Our classical atomistic simulation results confirm that larger cracks can reduce the strength of the phagraphene. Moreover, it was shown the temperature has a considerable weakening effect on the tensile strength of phagraphene. The results of this study may be useful for the design of nano-devices using the phagraphene.

关键词： phaqraphene mechanical properties crack propagation molecular dynamics thermal effects

Performance of a base isolator with shape memory alloy bars

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Earthquake Engineering and Engineering Vibration 2007年第4期6卷 401-408页

作者： Fabio Casciati Lucia Faravelli Karim Hamdaoui Dept. of structural mechanics University of Pavia Pavia Italy

A new and innovative base isolation device is introduced in this paper based on extensive research carried out by the authors and their co-workers. A prototype of the device was built and experimentally tested on the shaking table. The new base isolation device consists of two disks, one vertical cylinder with an upper enlargement sustained by three horizontal cantilevers, and at least three inclined shape memory alloy （SMA） bars. The role of the SMA bars is to limit the relative motion between the base and the superstructure, to dissipate energy by their super-elastic constitutive law and to guarantee the re-centring of the device. To verify the expected performance, a prototype was built and tested under sinusoidal waves of displacement of increasing frequency with different amplitudes. It is shown that the main feature of the proposed base isolation device is that for cyclic loading, the super-elastic behavior of the alloy results in wide load-displacement loops, where a large amount of energy is dissipated.

关键词： base isolator dynamic excitation energy dissipation shape memory alloy shaking table test

Shape design of arch dams under load uncertainties with robust optimization

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Frontiers of structural and Civil Engineering 2019年第4期13卷 852-862页

作者： Fengjie TAN Tom LAHMER Institute of structural mechanics Bauhaus-UniversitatWeimar D-99423Germany

Due to an increased need in hydro-electricity, water storage, and flood protection, it is assumed that a series of new dams will be build throughout the world. The focus of this paper is on the non-probabilistic-based design of new arch-type dams by applying means of robust design optimization (RDO). This type of optimization takes into account uncertainties in the loads and in the material properties of the structure. As classical procedures of probabilistic-based optimization under uncertainties, such as RDO and reliability-based design optimization (RBDO), are in general computationally expensive and rely on estimates of the system’s response variance, we will not follow a full-probabilistic approach but work with predefined confidence levels. This leads to a bi-level optimization program where the volume of the dam is optimized under the worst combination of the uncertain parameters. As a result, robust and reliable designs are obtained and the result is independent from any assumptions on stochastic properties of the random variables in the model. The optimization of an arch-type dam is realized here by a robust optimization method under load uncertainty, where hydraulic and thermal loads are considered. The load uncertainty is modeled as an ellipsoidal expression. Comparing with any traditional deterministic optimization method, which only concerns the minimum objective value and offers a solution candidate close to limit-states, the RDO method provides a robust solution against uncertainty. To reduce the computational cost, a ranking strategy and an approximation model are further involved to do a preliminary screening. By this means, the robust design can generate an improved arch dam structure that ensures both safety and serviceability during its lifetime.

关键词： arch dam shape optimization robust optimization load uncertainty approximation model

Numerical simulation of three dimensional concrete printing based on a unified fluid and solid mechanics formulation

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Frontiers of structural and Civil Engineering 2024年第4期18卷 491-515页

作者： Janis REINOLD Koussay DAADOUCH Günther MESCHKE Institute for structural mechanics Ruhr University BochumBochum 44801Germany

Deformation control constitutes one of the main technological challenges in three dimensional(3D)concrete printing,and it presents a challenge that must be addressed to achieve a precise and reliable construction ***-based information of the expected deformations and stresses is required to optimize the construction process in association with the specific properties of the concrete *** this work,a novel thermodynamically consistent finite strain constitutive model for fresh and early-age 3D-printable concrete is *** model is then used to simulate the 3D concrete printing process to assess layer shapes,deformations,forces acting on substrate layers and prognoses of possible structural collapse during the layer-by-layer *** constitutive formulation is based on a multiplicative split of the deformation gradient into elastic,aging and viscoplastic parts,in combination with a hyperelastic potential and considering evolving material properties to account for structural buildup or *** advantage of this model is the stress-update-scheme,which is similar to that of small strain plasticity and therefore enables an efficient integration with existing material *** constitutive model uses the particle finite element method,which serves as the simulation framework,allowing for modeling of the evolving free surfaces during the extrusion *** analyses of three printed layers are used to create deformation plots,which can then be used to control the deformations during 3D concrete *** study offers further investigations,on the structural level,focusing on the potential structural collapse of a 3D printed concrete *** capability of the proposed model to simulate 3D concrete printing processes across the scales—from a few printed layers to the scale of the whole printed structure—in a unified fashion with one constitutive formulation,is demonstrated.

关键词： particle finite element method 3D concrete printing multiplicative split additive manufacturing elastoviscoplasticity

Mechanical Properties of All MoS_(2) Monolayer Heterostructures:Crack Propagation and Existing Notch Study

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Computers, Materials & Continua 2022年第3期70卷 4635-4655页

作者： Reza Khademi Zahedi Naif Alajlan Hooman Khademi Zahedi Timon Rabczuk institiute of structural mechanics Bauhaus-Universit鋞WeimarWeimar99423Germany Department of Computer Engineering King Saud UniversityRiyadhSaudi Arabia Mechanical Engineering Department Islamic Azad UniversityNorth Tehran BranchIran

The outstanding thermal,optical,electrical and mechanical properties of molybdenum disolphide(MoS_(2))heterostructures make them exceptional candidates for an extensive area of ***,despite considerable technological and academic interest,there is presently a fewinformation regarding the mechanical properties of these novel two-dimensional(2D)materials in the presence of the *** thismanuscript,we performed extensive molecular dynamics simulations on pre-cracked and pre-notched all-molybdenum disolphide(MoS_(2))heterostructure systems using ReaxFF force ***,we study the influence of several central-crack lengths and notch diameters on the mechanical response of 2H phase,1T phase and composite 2H/1T MoS_(2) monolayers with different concentrations of 1T phase in 2H phase,under uniaxial tensile loading at room *** ReaxFF models reveal that larger cracks and notches decrease the strength of all 2D MoS_(2) single-layer ***,for all studied crack and notch sizes,2H phase of MoS_(2) films exhibits the largest *** tensile stress of composite 2H/1T MoS_(2) nanosheet with different concentrations are higher than those for the equivalent 1T phase,which implies that the pre-cracked composite structure is remarkably stronger than the equivalent 1T *** comparison of the results for cracked and notched all-MoS_(2) nanosheet heterostructures reveal that the load bearing capacity of the notched samples of monolayerMoS_(2) are higher than the cracked ones.

关键词： Molybdenum disulphide(MoS_(2)) molecular dynamics simulations uniaxial tension cracks notches

From advance exploration to real time steering of TBMs:A review on pertinent research in the Collaborative Research Center.“Interaction Modeling in Mechanized Tunneling”

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Underground Space 2018年第1期3卷 1-20页

作者： G.Meschke Institute for structural mechanics Ruhr University BochumBochumGermany

This paper reports on planning and construction related results from research performed at the Collaborative Research Center“Interaction Modeling in Mechanized Tunneling”at Ruhr-University Bochum,*** covers a broad spectrum of topics relevant for mechanized tunneling in soft soil *** includes inverse numerical methods for advance exploration and models for the characterization of the in situ ground conditions,the interaction of the face support and the tail gap grouting with the porous soil,multi-scale models for the design ofﬁber reinforced segmental linings with enhanced robustness,computational methods for the numer-ical simulation of the tunnel advancement,the soil excavation and the material transport in the pressure chamber,logistics processes and risk analysis in urban *** towards the continuous support of the construction process,a concept for real-time steering support of tunnel boring machines in conjunction with model update procedures and methods of uncertainty quantiﬁcation is addressed.

关键词： Mechanized tunneling Computational simulation Tunnel reconnaissance Tunnel linings Face support Tail void grouting Real-time ana-lysis Abrasion Process simulation