A Microgripper with a Large Magnification Ratio and High Structural Stiffness Based on a Flexure-Enabled Mechanism

2021 ◽  
pp. 1-1
Author(s):  
Chaoyang Shi ◽  
Xinyu Dong ◽  
Zhan Yang
Keyword(s):  
Structural Stiffness ◽  
Magnification Ratio ◽  
Large Magnification

Development of a Testing Apparatus for Structural Stiffness Evaluation of Ankle-Foot Orthoses

2001 ◽  
Vol 13 (3) ◽  
pp. 74-82 ◽  
Author(s):  
Adrian A. Polliack ◽  
Christopher Swanson ◽  
Samuel E. Landsberger ◽  
Donald R. McNeal
Keyword(s):  
Foot Orthoses ◽  
Structural Stiffness ◽  
Testing Apparatus ◽  
Stiffness Evaluation ◽  
Ankle Foot Orthoses

scholarly journals Evaluasi dan Retrofit Struktur Gedung Beton Bertulang Akibat Kebakaran

2021 ◽  
Vol 17 (1) ◽  
pp. 57-67
Author(s):  
Nurul Hidayati ◽  
Henricus Priyosulistyo ◽  
Andreas Triwiyono
Keyword(s):  
Site Investigation ◽  
Office Building ◽  
Building Structure ◽  
Structural Stiffness ◽  
Structural Elements ◽  
Concrete Material ◽  
Steel Bracing ◽  
The Cost ◽  
The Impact ◽  
Cfrp Wrapping

ABSTRACT Several studies have been carried out related to the impact of fire on the strength of reinforced concrete material. It shows that there is a decrease in strength and a decrease in structural stiffness. The degree of damage is dependent on the temperature and duration of the fire. To ensure accessibility, the building needs to be evaluated whether the building can be re-functioned immediately. The results of site investigation are evaluated to determine the structure retrofit and reinforcement methods and cost-effectiveness compared to the cost of a new building. The office building structure under review is analytically evaluated based on SNI 1726:2019 and SNI 1727:2018. The results showed that 31% of columns and 32% of beams need to be strengthened. In addition, steel bracing and CFRP wrapping on the structural elements were applied. The cost of retrofitting required Rp2.998.488.781,07, which is lower than the cost of the new building structure, which costs Rp4.950.087.016,34. ABSTRAKBeberapa penelitian yang telah dilakukan terkait dampak kebakaran terhadap kekuatan material beton bertulang, memperlihatkan bahwa terdapat penurunan kekuatan dan kapasitas struktur. Tingkat penurunan tergantung antara lain pada suhu dan durasi kebakaran. Untuk meyakinkan tingkat fisibilitas, gedung tersebut perlu dievaluasi kemungkinan dapat atau tidaknya gedung itu difungsikan kembali. Hasil evaluasi tersebut dijadikan pertimbangan dalam menentukan metode perbaikan dan perkuatan yang efektif untuk kemudian dibandingkan dengan biaya pembangunan gedung baru. Struktur gedung kantor PLN Unit Cabang Distribusi Jakarta Raya ini akan dievaluasi dengan cara analitis berdasarkan SNI 1726:2019 dan SNI 1727:2018. Terdapat total 31% kolom dan 32% balok yang perlu diperkuat. Metode perkuatan yang digunakan adalah penambahan bracing baja dan CFRP. Material CFRP tersebut dililitkan pada elemen struktur. Biaya perkuatan yang diperlukan adalah Rp2.998.488.781,07, lebih rendah dibandingkan nilai struktur gedung, yaitu Rp4.950.087.016,34.

Development of planar rigid-elastic coupling tyre model with analytical multi-stiffness sidewall

2018 ◽  
Vol 233 (2) ◽  
pp. 299-316
Author(s):  
Zhihao Liu ◽  
Qinhe Gao
Keyword(s):  
Structural Deformation ◽  
Geometrical Parameters ◽  
Radial Deformation ◽  
Elastic Coupling ◽  
Structural Stiffness ◽  
Inflation Pressure ◽  
Large Section ◽  
Tyre Model ◽  
Section Ratio ◽  
Non Linear

In this study, combining the membrane feature with inflation pressure and the structural deformation caused by sidewall curvature, rigid-elastic coupling tyre model with analytical multi-stiffness sidewall is proposed for a heavy-loaded radial tyre with a large section ratio. The membrane pre-tension of sidewall arc resulting from inflation pressure is investigated. By means of virtual work principle, the structural deformation of sidewall curved arc resulting from the arc curvature, including stretching, bending and shearing deformation is derived. The structural stiffness caused by the sidewall curvature and membrane pre-tension caused by the inflation pressure are combined for the multi-stiffness sidewall model. The influence of the sidewall structural and geometrical parameters on the sidewall multi-stiffness, modal resonant frequency and transfer function is researched and discussed. The non-linear characteristic of sidewall multi-stiffness with respect to the sidewall radial deformation is investigated. Experimental and theoretical results show that: (1) the multi-stiffness of sidewall can characterise the membrane-tension stiffness caused by inflation pressure and the structural stiffness led by the sidewall curvature and material properties; (2) the different multi-stiffnesses of upper and lower sidewall arcs results from the different interval angles; (3) the multi-stiffness of sidewall is non-linear to the radial sidewall deformation. Taking the flexible deformation of tyre carcass and the analytical multi-stiffness of tyre sidewall into consideration, rigid-elastic coupling tyre model with multi-stiffness sidewall is suitable for the heavy-loaded radial tyre with a large section ratio or tyres under impulsive loading and large deformation.

scholarly journals Wavelet-based analysis of time-variant adaptive structures

2018 ◽  
Vol 376 (2126) ◽  
pp. 20170245 ◽  
Author(s):  
Kajetan Dziedziech ◽  
Alexander Nowak ◽  
Alexander Hasse ◽  
Tadeusz Uhl ◽  
Wiesław J. Staszewski
Keyword(s):  
Frequency Response Function ◽  
Natural Frequencies ◽  
Fibre Composite ◽  
Structural Response ◽  
Structural Stiffness ◽  
Theme Issue ◽  
Adaptive Structures ◽  
Output Characteristics ◽  
Variant System

Wavelet analysis is applied to identify the time-variant dynamics of adaptive structures. The wavelet-based power spectrum of the structural response, wavelet-based frequency response function (FRF) and wavelet-based coherence are used to identify continuously and abruptly varying natural frequencies. A cantilever plate with surface-bonded macro fibre composite—which alters the structural stiffness—is used to demonstrate the application of the methods. The results show that the wavelet-based input–output characteristics—i.e. the FRF and coherence—can identify correctly the dynamics of the analysed time-variant system and reveal the varying natural frequency. The wavelet-based coherence can be used not only for the assessment of the quality of the wavelet-based FRF but also for the identification. This article is part of the theme issue ‘Redundancy rules: the continuous wavelet transform comes of age’.

Design guidelines for bump-type compliant conical foil bearing

2021 ◽  
pp. 095440622110127
Author(s):  
Hongyang Hu ◽  
Ming Feng
Keyword(s):  
Load Capacity ◽  
Design Guidelines ◽  
Foil Thickness ◽  
Axial Stiffness ◽  
Structural Stiffness ◽  
Foil Bearing ◽  
Stiffness Model ◽  
Opposite Position ◽  
Stiffness Distribution ◽  
Half Length

The integral bump foil strip cannot optimize the performance for the compliant conical foil bearing (CFB) as the uneven distribution of structural stiffness. To maximize the bearing characteristics, this paper proposed different bump foil schemes. Firstly, the anisotropy of CFB was studied based on the nonlinear bump stiffness model, and the circumferentially separated foil structure was proposed. Moreover, an axially separated bump foil structure with the variable bump length was introduced to make the axial stiffness distribution more compliant with the gas pressure. In addition, the effect of foil thickness was also discussed. The results show that CFB with integral bump foil exhibits obvious anisotropy, and the suggested installation angle for largest load capacity and best dynamic stability are in the opposite position. Fortunately, a circumferential separated bump foil can improve this defect. The characteristics of CFB with axial separated foil structure can be improved significantly, especially for that with more strips and the variable bump half-length design. The suitable bump and top foil thickness should be set considering the improved supporting performance and proper flexibility. The results can give some guidelines for the design of CFB.

Inelastic Analysis of Reinforced Concrete Shear Wall Structures Under Seismic Excitation

1993 ◽  
Author(s):  
Ming L. Wang
Keyword(s):  
Reinforced Concrete ◽  
Response Spectra ◽  
Shear Wall ◽  
Stiffness Degradation ◽  
Structural Stiffness ◽  
Hysteresis Model ◽  
Safety Equipment ◽  
Floor Response Spectra ◽  
Wall Structures ◽  
Degradation Models

Abstract During strong ground motions, members of reinforced concrete structures undergo cyclic deformations and experience permanent damage. Members may lose their initial stiffness as well as strength. Recently, Los Alamos National Laboratory has performed experiments on scale models of shear wall structures subjected to recorded earthquake signals. In general, the results indicated that the measured structural stiffness decreased with increased levels of excitation in the linear response region. Furthermore, a significant reduction in strength as well as in stiffness was also observed in the inelastic range. Since the in-structure floor response spectra, which are used to design and qualify safety equipment, have been based on calculated structural stiffness and frequencies, it is possible that certain safety equipment could experience greater seismic loads than specified for qualification due to stiffness reduction. In this research, a hysteresis model based on the concept of accumulated damage has been developed to account for this stiffness degradation both in the linear and inelastic ranges. Single and three degrees of freedom seismic Category I structures were analyzed and compared with equivalent linear stiffness degradation models in terms of maximum displacement responses, permanent displacement, and floor response spectra. The results indicate significant differences in responses between the hysteresis model and equivalent linear stiffness degradation models. The hysteresis model is recommended in the analysis of reinforced concrete shear-wall structures to obtain the in-structure floor response spectra for equipment qualification. Results of both cumulative and one shot tests are compared.

The Effect of Structural Parameters on Response Characteristics of Aeroelastic System in the Presence of Dynamic Stall

2021 ◽  
Author(s):  
Zhan Qiu ◽  
Fuxin Wang
Keyword(s):  
Limit Cycle ◽  
Structural Parameters ◽  
Dynamic Pressure ◽  
Angle Of Attack ◽  
Dynamic Stall ◽  
System Response ◽  
Structural Stiffness ◽  
Aeroelastic System ◽  
Equilibrium Angle ◽  
Minimum Angle

Abstract The effect of structural paramters on the response and aerodynamic stiffness characteristics of the free aeroelastic system under the influence of dynamic stall is investigated adopting CFD (Computational Fluid Dynamics) method. The equilibrium angle of the spring and the structural stiffness are taken as parameters of interest. Systems with small equilibrium angles enter the symmetric limit-cycle state more quickly after a Hopf bifurcation and experience dynamic stall in both directions, rather than slowly decreasing in minimum angle of attack and remaining in the asymmetric limit-cycle state before dynamic stall in the opposite direction, as is the case with systems with large spring equilibrium angles. Thus, aerodynamic stiffness of system with large equilibrium angles can be more significantly influenced by the change in aerodynamic moment characteristics at the minimum angle of attack. Furthermore, by increasing the initial angular velocity, we find that the system response all becomes symmetric limit cycle and therefore the aerodynamic stiffness appears to have a monotonically increasing characteristic. As to the effect of structural stiffness, it is found that the limit cycle amplitude first increases with structural stiffness after bifurcation, then the amplitude is unchanged with varying structural stiffness at higher Mach number. Energy maps show that the parametric distribution of the energy transfer contributes to this phenomenon. Moreover, when entering the symmetric limit cycle state, the structural stiffness no longer has a significant effect on the aerodynamic stiffness of the system, as the increase in the aerodynamic stiffness is determined solely by the increase in dynamic pressure without the effect of changes in moment characteristics.

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