Some Topics in Recent Advances and Applications of Structural Impact Dynamics

2011 ◽  
Vol 64 (3) ◽  
Author(s):  
X. M. Qiu ◽  
T. X. Yu
Keyword(s):  
Experimental Studies ◽  
Rate Sensitivity ◽  
Cellular Materials ◽  
Dynamic Responses ◽  
Stress Wave Propagation ◽  
Impact Dynamics ◽  
Structural Members ◽  
Transverse Loading ◽  
Time Dynamic ◽  
Structural Impact

This paper reviews some topics related to the advances and applications of structural impact dynamics in recent years. Dynamic behavior of structural members including tubes, beams and plates under axial or transverse loading, and cellular materials and sandwich structures under impact or blast loading are summarized here. The research methodology involves experimental studies, theoretical modeling, as well as numerical simulations. However, as we mainly focus on the longer time dynamic responses of structures and cellular materials, studies of stress wave propagation and the material's strain-rate sensitivity are not included.

scholarly journals A Novel Piezoceramic-Based Sensing Technology Combined With Visual Domain Networks for Timber Damage Quantification

2021 ◽  
Vol 8 ◽  
Author(s):  
Haibei Xiong ◽  
Lin Chen ◽  
Cheng Yuan ◽  
Qingzhao Kong
Keyword(s):  
Time Domain ◽  
Damage Assessment ◽  
Structural Damage ◽  
High Efficiency ◽  
Experimental Studies ◽  
Stress Wave Propagation ◽  
Timber Structures ◽  
Sensing Technology ◽  
The Time Domain ◽  
Visual Domain

Early detection of timber damage is essential for the safety of timber structures. In recent decades, wave-based approaches have shown great potential for structural damage assessment. Current damage assessment accuracy based on sensing signals in the time domain is highly affected by the varied boundary conditions and environmental factors in practical applications. In this research, a novel piezoceramic-based sensing technology combined with a visual domain network was developed to quantitatively evaluate timber damage conditions. Numerical and experimental studies reveal the stress wave propagation properties in different cases of timber crack depths. Through the spectrogram visualization process, all sensing signals in the time domain were transferred to images which contain both time and frequency features of signals collected from different crack conditions. A deep neural network (DNN) was adopted for image training, testing, and classification. The classification results show high efficiency and accuracy for identifying crack conditions for timber structures. The proposed technology can be further integrated with a fielding sensing system to provide real-time monitoring of timber damage in field applications.

Experimental Studies of Hydrodynamics and Heat Transfer in Channels With High-Porous Cellular Materials in Single-Phase Forced Convection and Flow Boiling of Working Fluids

1999 ◽  
Author(s):  
Yury F. Gortyshov ◽  
Igor A. Popov ◽  
Konstantin E. Gulitsky
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Pore Diameter ◽  
Flow Boiling ◽  
Experimental Studies ◽  
Internal Heat ◽  
Cellular Materials ◽  
Heat Fluxes ◽  
Working Fluids ◽  
Resistance Surface

Abstract In this paper we consider experimental studies of hydraulic resistance, surface heat transfer, internal heat exchange and critical heat fluxes for the flow of single-phase and boiling working fluids in channels with high-porous inserts. Experiments were carried out with more than 40 samples of high-porous cellular materials with the porosity 0.8...0.98 and mean pore diameter 0.62...4 mm and with more than 10 samples of regular porous inserts and porosity ε = 0.512...0.86 and mean pore diameter 1.5...3.5 mm. These samples were made of porcelain, invar, nichrome, bronze and copper.

Correlating Dynamic Bifurcations With Impedance Measures for Multistable Structures

2017 ◽  
Author(s):  
Benjamin A. Goodpaster ◽  
Ryan L. Harne
Keyword(s):  
Experimental Studies ◽  
High Amplitude ◽  
Structural Members ◽  
Lightweight Structures ◽  
Vehicle System ◽  
System Characterization ◽  
Dynamic Excitations ◽  
Dynamic Bifurcations ◽  
Experimental Strategies ◽  
Solution Formulation

Slender, lightweight structures are demanded to meet efficiency targets or to enhance vehicle system performance characteristics. Yet, when subjected to static stress for load-bearing purposes, the flexible structural members may buckle. Furthermore, additional dynamic excitations may activate adverse snap-through responses in such post-buckled components, which accelerates fatigue and failure. The severe nonlinearity associated with these phenomena challenges traditional forms of analysis and necessitates studious experimental methods for conclusive system characterization and model validation. This research builds upon state-of-the-art analytical and experimental strategies to examine the complex forced, dynamic behaviors of built-up structures that contain one or more post-buckled members. An analytical modeling and solution formulation is reviewed that is uniquely amenable to the study of multistable structures and permits experimentally-observable measures of impedance to be identified. Through theoretical and experimental studies, the efficacy of the impedance measures is evaluated towards their usefulness in identifying the onset of dynamic bifurcations in the multistable structural dynamics. For moderate amplitudes of input energy, the analysis is found to provide qualitatively accurate prediction of the drive point impedance changes observed prior to dynamic bifurcations from low to high amplitude of displacement.

A Simplified Method for Response Behavior and Reliability Analysis of Long Submerged Structures With Tension Legs in Irregular Waves

2002 ◽  
Author(s):  
Shinji Katsura ◽  
Hiroo Okada ◽  
Koji Masaoka ◽  
Takashi Tsubogo ◽  
Kiko Shimada
Keyword(s):  
Limit State ◽  
Experimental Studies ◽  
Estimation Method ◽  
Dynamic Responses ◽  
Irregular Waves ◽  
Elastic Response ◽  
Tunnel Structure ◽  
Wave Loads ◽  
Response Behavior ◽  
Wave Conditions

This paper deals with the elastic response behavior of marine tunnel structures with tension legs in regular and irregular waves. Firstly, a simplified estimation method for dynamic responses under regular wave conditions is analytically presemed using a simple beam on an elastic foundation. Then, in order to demonstrate the validity of above results, experimental studies are carried out for a marine tunnel structure model with tension legs under wave-induced loads. Next, a simplified estimation method is presented for the elastic response behavior under irregular wave conditions by using above analytical results and combining irregular sea wave spectra. Then, the limit state failure mode of the main structure is presented for estimating the reliability level for cracking failure under extreme wave loads. Finally, the applicability of the methods is investigated through numerical examples carried out for a 1,000m-class marine tunnel structure with tension legs under some irregular sea state conditions. And characteristics of the short-term responses and reliability levels for the cracking failure are numerically shown.

An Estimation of Joint Strength by Using Fe-Based Shape Memory Alloy Subjected to Bending Deformation at Various Deformation Rate

2014 ◽  
Vol 626 ◽  
pp. 228-233 ◽  
Author(s):  
Kazuki Fujita ◽  
Keizo Nishikori ◽  
Takeshi Iwamoto
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Deformation Rate ◽  
Bending Strength ◽  
Rate Sensitivity ◽  
Force Balance ◽  
Bending Test ◽  
Structural Members ◽  
Bending Deformation ◽  
Three Point Bending

In various kinds of shape memory alloy (SMA), Fe-based SMA (Fe-SMA) shows smaller shape memory effect compared with the other SMAs. However, Fe-SMA shows huge advantages on the excellent formability, machinability, etc. Moreover, its production cost is cheaper than other SMAs; therefore, the alloy is attempted to be applied to structural members such as joints and dampers. Since bending deformation at higher deformation rate is generated in the members, especially the joints, due to impact force such as earthquake or wind, a clarification on the bending strength of the joints at various deformation rate is strongly required. In this study, at first, it is attempted that the bending strength and its rate sensitivity of the joints which consist of Fe-based SMA are experimentally estimated by the three-point bending test at various deformation rate. Then, the force balance equation is challenged to be derived to predict the bending strength.

Numerical and experimental studies on impact dynamics of a planar flexible multibody system

2010 ◽  
Vol 26 (4) ◽  
pp. 635-642 ◽  
Author(s):  
Fu-Xiang Dong ◽  
Jia-Zhen Hong ◽  
Kun Zhu ◽  
Zheng-Yue Yu
Keyword(s):  
Multibody System ◽  
Experimental Studies ◽  
Impact Dynamics ◽  
Flexible Multibody System ◽  
Flexible Multibody

scholarly journals Assessment of structural nonlinearities employing extremes of dynamic responses

2016 ◽  
Vol 24 (1) ◽  
pp. 137-152 ◽  
Author(s):  
Vikram Pakrashi ◽  
Paul Fitzgerald ◽  
Michael O’Leary ◽  
Vesna Jaksic ◽  
Kevin Ryan ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Theoretical Models ◽  
Parameter Tuning ◽  
Dynamic Responses ◽  
Structural Systems ◽  
Structural System ◽  
Single Degree Of Freedom ◽  
Nonlinear Responses ◽  
Structural Nonlinearities ◽  
Measurement Devices

A range of methodologies exist for estimating nonlinear responses of structural systems using numerical simulations. However, efforts in relation to experimental methods in this regard still warrant further investigation. This paper presents an approach for assessing structural nonlinearities using the extremes of dynamic responses of the structural system under consideration. The approach allows revisiting and parameter tuning of theoretical models of structures based on experimental studies. A single degree of freedom system was excited in this study using broadband input excitations and the output dynamic responses were measured using different devices. The type and extent of experimentation required for implementation of the presented technique was investigated along with the effects of the estimates of the measured variables and the effects related to different measurement devices.

scholarly journals Simulation Study on Train-Induced Vibration Control of a Long-Span Steel Truss Girder Bridge by Tuned Mass Dampers

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Hao Wang ◽  
Tianyou Tao ◽  
Huaiyu Cheng ◽  
Xuhui He
Keyword(s):  
Vibration Control ◽  
Bridge Engineering ◽  
Dynamic Responses ◽  
Fe Method ◽  
Time Dynamic ◽  
Control Efficiency ◽  
Truss Bridges ◽  
Steel Truss ◽  
Steel Truss Bridges ◽  
Train Induced Vibration

Train-induced vibration of steel truss bridges is one of the key issues in bridge engineering. This paper talks about the application of tuned mass damper (TMD) on the vibration control of a steel truss bridge subjected to dynamic train loads. The Nanjing Yangtze River Bridge (NYRB) is taken as the research object and a recorded typical train load is included in this study. With dynamic finite element (FE) method, the real-time dynamic responses of NYRB are analyzed based on a simplified train-bridge time-varying system. Thereinto, two cases including single train moving at one side and two trains moving oppositely are specifically investigated. According to the dynamic characteristics and dynamic responses of NYRB, the fourth vertical bending mode is selected as the control target and the parameter sensitivity analysis on vibration control efficiency with TMD is conducted. Using the first-order optimization method, the optimal parameters of TMD are then acquired with the control efficiency of TMD, the static displacement of Midspan, expenditure of TMDs, and manufacture difficulty of the damper considered. Results obtained in this study can provide references for the vibration control of steel truss bridges.

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