dynamic responses
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2022 ◽  
Vol 165 ◽  
pp. 108268
Author(s):  
Andreia Meixedo ◽  
João Santos ◽  
Diogo Ribeiro ◽  
Rui Calçada ◽  
Michael D. Todd

2022 ◽  
Vol 9 ◽  
Author(s):  
Xiaochao Zhang ◽  
Qingwen Yang ◽  
Xiangjun Pei ◽  
Ruifeng Du

As blasting technology starts to be used in a wide range of areas, blast loading has led to an increasing number of geological disasters such as slope deformation, collapses, and soil slippage. Slopes with weak interlayers are more likely to be deformed and damaged under the influence of blast loading. It is of great importance to study the evolution for the deformation of slopes with weak interlayers during blasting excavation. This study constructed a slope model with a weak interlayer to investigate the influence of different factors of blasting, including explosive charge, blast radius, blast origin, and multi-hole blasting, on the internal dynamic response. The deformation mechanism of slopes with weak interlayers under the influence of blast loading was analyzed. Test results show that each layer of the model had a different displacement response (uncoordinated dynamic response) to blasting with various factors. Explosive energy and the pattern of dynamic response of each layer varied depending on different settings of blasting factors such as explosive charge, blast radius, blast origin, and detonation initiation method. When the explosive energy produced under the influence of various factors was small, the change in the uncoordinated dynamic response between layers was significant, and the change gradually became less significant as the explosive energy increased. Therefore, this study has proposed the concept of critical explosive energy, and it is speculated that when the explosive energy produced with various factors is less than critical explosive energy, the dynamic response is mainly affected by the internal structure of the slope (property difference induced geologic layers). In other words, the uncoordinated motion of material’s particles in each layer is caused by different limitations and the degree of movement of the particles, which leads to the uncoordinated dynamic response and uncoordinated deformation of each layer. If the explosive energy is greater than the critical value, the dynamic response of each layer is mainly affected by the explosive energy. The differences in the internal structure of the slope are negligible, and the incoordination of dynamic responses between layers gradually weakens and tends to synchronize.


Vibration ◽  
2022 ◽  
Vol 5 (1) ◽  
pp. 20-58
Author(s):  
Xiaoquan Wang ◽  
Ricardo A. Perez ◽  
Bret Wainwright ◽  
Yuting Wang ◽  
Marc P. Mignolet

The focus of this investigation is on reduced order models (ROMs) of the nonlinear geometric response of structures that are built nonintrusively, i.e., from standard outputs of commercial finite element codes. Several structures with atypical loading, boundary conditions, or geometry are considered to not only support the broad applicability of these ROMs but also to exemplify the different steps involved in determining an appropriate basis for the response. This basis is formed here as a combination of linear vibration modes and dual modes, and some of the steps involved follow prior work; others are novel aspects, all of which are covered in significant detail to minimize the expertise needed to develop these ROMs. The comparisons of the static and dynamic responses of these structures predicted by the ROMs and by the underlying finite element models demonstrate the high accuracy that can be achieved with the ROMs, even in the presence of significant nonlinearity.


2022 ◽  
pp. 107754632110495
Author(s):  
ZhaoYuan Yao ◽  
JunGuo Wang ◽  
YongXiang Zhao

In this study, an innovative modeling approach is put forward to research the effect of eccentricity on the nonlinear dynamical behaviors of geared-bearing system. This refined model contains the rigid body of the rotor-bearing system and separated gear teeth which are considered as individual bodies elastically attached to the gear hub with revolute joints. The internal and external excitations of the proposed model include torsional joint stiffness, roll bearing forces, friction between gear pair, gear eccentricity, and so on. The systematic procedure for the calculation of torsional joint stiffness, bearing forces and friction coefficient considering elastohydrodynamic is also conducted. After that, the influence of eccentricity on nonlinear dynamic characteristics of the geared transmission system is analyzed. To avoid the system moving in the unstable motion state, a dry friction damper controller is designed to control the nonlinear behaviors simulated on the basis of above model. The linear feedback and periodic excitation non-feedback control strategies are, respectively, selected to design the actuator. It is indicated that undesirable behaviors of the geared transmission system can be avoided effectively by applying the proposed control method.


Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 535
Author(s):  
Jianqin Wu ◽  
Jiannan Zhou ◽  
Ying Xu ◽  
Xinli Kong ◽  
Peng Wang ◽  
...  

This paper proposes a prefabricated basalt fiber reinforced polymer (BFRP) bars reinforcement of a concrete arch structure with superior performance in the field of protection engineering. To study the anti-blast performance of the shallow-buried BFRP bars concrete arch (BBCA), a multi-parameter comparative analysis was conducted employing the LS-DYNA numerical method, which was verified by the results of the field explosion experiments. By analyzing the pressure, displacement, acceleration of the arch, and the strain of the BFRP bars, the dynamic response of the arch was obtained. This study showed that BFRP bars could significantly optimize the dynamic responses of blast-loaded concrete arches. The damage of exploded BBCA was divided into five levels: no damage, slight damage, obvious damage, severe damage, and collapse. BFRP bars could effectively mitigate the degree of damage of shallow-buried underground protective arch structures under the explosive loads. According to the research results, it was feasible for BFRP bars to be used in the construction of shallow buried concrete protective arch structures, especially in the coastal environments.


Aerospace ◽  
2022 ◽  
Vol 9 (1) ◽  
pp. 30
Author(s):  
Wenyan Gu ◽  
Jinsheng Zhang ◽  
Longye Pan ◽  
Yegao Qu ◽  
Jin-Hwan Choi ◽  
...  

Many solar panels for spacecrafts are deployed by Tape Spring Hinges (TSHs) which have changeable stiffness. The stiffness of TSH is small when panels are folded, and it becomes large quickly in its deployed status. Since the solar panel is a thin sheet, flexible deformation is easily generated by orbit maneuvers. The coupling effect between the nonlinear TSHs and the flexible panels generates obvious vibration which affects the operational stability of the satellite. To investigate this coupling effect, non-deformable, linear deformable and nonlinear deformable panels were modelled by rigid body, modal order reduction method (MORM) and finite element method (FEM), respectively. The driving torque of TSH was described as a function of the rotation angle and angular velocity. The nonlinear properties of the TSH were reflected by one angle-stiffness spline multiplied by one stiffness coefficient. Dynamic responses of a satellite in deployment and orbit steering were analyzed by numerical simulations. Analysis results indicate the local deformation of panels keeps the stiffness of the TSH within a large range which accelerates the orbit maneuvers. However, much vibration is generated by the coupling effect if the luck-up status is broken up. The coupling effect affects the sequence of deployment, overshoot phenomenon and acceleration magnitude of the panels. Although the MORM is more efficient than FEM in computation, we propose FEM is better suited in the design of TSH and in studying the precise control of spacecraft with flexible solar panels and TSHs.


Wind ◽  
2022 ◽  
Vol 2 (1) ◽  
pp. 17-36
Author(s):  
Lilantha Samaranayake ◽  
Carlos E. Ugalde-Loo ◽  
Oluwole D. Adeuyi ◽  
John Licari ◽  
Janaka B. Ekanayake

With the development of offshore wind generation, the interest in cross-country connections is also increasing, which requires models to study their complex static and dynamic behaviors. This paper presents the mathematical modeling of an offshore wind farm integrated into a cross-country HVDC network forming a multi-terminal high-voltage DC (MTDC) network. The voltage source converter models were added with the control of active power, reactive power, frequency, and DC link voltages at appropriate nodes in the MTDC, resembling a typical cross-country multi-terminal type of HVDC scenario. The mathematical model for the network together with the controllers were simulated in MATLABTM and experimentally verified using a real-time digital simulator hardware setup. The resulting static and dynamic responses from the hardware setup agreed well with those from simulations of the developed models.


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