scholarly journals Matrix and reinforcement materials for low-cost building isolators: an overview of results from experimental tests and numerical simulations

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Ingrid E. Madera Sierra ◽  
Johannio Marulanda Casas ◽  
Peter Thomson
Keyword(s):  
Low Cost ◽  
Experimental Tests ◽  
Steel Plates ◽  
Analytical Models ◽  
Compression Tests ◽  
Horizontal Shear ◽  
Scrap Tire ◽  
Element Analysis ◽  
Isolation System ◽  
Scrap Tire Rubber

During the last years several options to replace the conventional steel-reinforced isolators have been investigated using different materials for the matrix and reinforcement to implement isolation system in buildings. As alternatives to natural rubber, recycled elastomers derived from tires and industrial leftover, scrap tire rubber pads and nanocomposite rubber, have been proposed. Furthermore, with the goal of replacing the inflexible, thick steel plates, a wide variety of fabric reinforcements, such as nylon, carbon, polyester, polyamide, glass and thin flexible steel plates, have been investigated. The manufacturing process and connections between the devices and the structure (bonded, unbonded and partially bonded) have also been studied. This paper presents an overview of the results from investigations where the mechanical properties of prototypes were determined through horizontal shear and vertical compression tests and, in certain cases, through finite element analysis with hyperelastic models. In order to facilitate the visualization and comparison between investigations, the results are tabulated and plotted. The organization and presentation of the results allows to identify important aspects implemented in different experimental programs and analytical models developed for low-cost isolators.

scholarly journals Design of a 3-RPR Flexure System for Optical Switch Assembly

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Guiyue Kou ◽  
Mouyou Lin ◽  
Changbao Chu
Keyword(s):  
Permanent Magnets ◽  
Optical Switch ◽  
Low Cost ◽  
Mechanical Vibration ◽  
Analytical Models ◽  
Assembly System ◽  
Sensors And Actuators ◽  
Damping Force ◽  
Element Analysis ◽  
Compact Size

In the MEMS optical switch assembly, the collision is likely to happen between the optical fiber and the U-groove of the chip due to the uncontrollable assembly errors. However, these errors can hardly be completely eliminated by the active control using high precision sensors and actuators. It will cause the large acting force and part damage, which further leads to the assembly failure. To solve this question, this paper presents a novel low-cost three-degree-of-freedom (three-DOF) passive flexure system to adaptively eliminate the planar assembly errors. The flexure system adopts three parallel kinematic chains with a novel 3-RPR structure and has a compact size with a diameter of 125 mm and thickness of 12 mm. A novel eddy current damper with the structure of Halbach array permanent magnets (PMs) is utilized to suppress the adverse mechanical vibration of the assembly system from the background disturbances. Analytical models are established to analyze the kinematic, static, and dynamic performances of the system in detail. Finally, finite element analysis is adopted to verify the established models for optimum design. The flexure system can generate a large deformation of 1.02 mm along the two translational directions and 0.02° along the rotational direction below the yield state of the material, and it has much higher natural frequencies than 200 Hz. Moreover, the large damping force means that the designed ECD can suppress the system vibration quickly. The above results indicate the excellent characteristics of the assembly system that will be applied into the optical switch assembly.

Evaluation of unbonded Strip-STRP bearing based on current design guidelines

2021 ◽  
Author(s):  
M. B. Zisan ◽  
A. Igarashi
Keyword(s):  
Design Guidelines ◽  
Effective Length ◽  
Scrap Tire ◽  
Stress Strain ◽  
Element Analysis ◽  
Vertical Stiffness ◽  
Seismic Isolator ◽  
Current Design ◽  
Scrap Tire Rubber ◽  
Analytical Result

<p>The scrap tire rubber pad (STRP) made of natural or synthetic rubber offers substantial vertical stiffness and lateral flexibility, which are suitable properties for seismic isolator application. If a stacked STRP is used as an unbonded seismic isolator, the in-service stress-strain and displacement demand when rollover deformation is allowed can be different from that without considering the rollover. Although design guidelines are currently available for bonded type bearings, there are no established criteria for the unbonded bearings. To investigate the performance and stress-strain demand of unbonded strip-STRP isolators, finite element analysis (FEA) is performed to compare the analytical result with the existing design guidelines. The stress-strain demand of the strip-STRP isolators is substantially influenced by the <i>l/w </i>ratio, and it is found that the in-plane stresses are the key parameters in the determination of the allowable displacement and the effective length. The analysis shows that an STRP isolator carrying a vertical load of 5.0 MPa can efficiently be utilized up to 230% shear deformation.</p>

Improvement of the polyurethane spring isolation device for HV post insulators and its evaluation by fragility curves

2021 ◽  
pp. 875529302098196
Author(s):  
Tansu Gökçe ◽  
Engin Orakdöğen ◽  
Ercan Yüksel
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Numerical Models ◽  
Fragility Curves ◽  
Low Cost ◽  
Steel Plates ◽  
Isolation System ◽  
Base Isolation System ◽  
Isolation Device ◽  
Seismic Base Isolation

A novel seismic base isolation system has been developed for high-voltage (HV) porcelain post insulators. The seismic isolation device consists of two steel plates, four polyurethane springs, and a steel rod, which are low-cost components compared to the post insulators. Two alternative designs of the device are experimentally and numerically assessed in this article. A simple and robust numerical model consisting of linear line elements and nonlinear springs was generated, and subsequently validated using the experimental results. Incremental dynamic analyses (IDAs) were then performed to obtain fragility curves. Ten historical earthquake profiles, scaled to intensities between 0.1 and 2.0 g, were then applied to the numerical models. The fragility curves, generated according to the latest version of IEEE-693, demonstrate that the seismic isolation devices are highly effective in diminishing the base moment of the porcelain insulator. It should be noted that relatively large displacements at the top of the pole must be accounted for by ensuring adequate slackness in the flexible conductors.

Low Cost Friction Pendulum-Type Earthquake Isolation Device With Poly-Curvature Suitable for Light-Weight Equipment

2004 ◽  
Author(s):  
Satoshi Fujita ◽  
Hiroshi Kurabayashi ◽  
Hiromichi Yamamoto
Keyword(s):  
Low Cost ◽  
Experimental Tests ◽  
Response Analysis ◽  
Shake Table Tests ◽  
Isolation System ◽  
Vending Machines ◽  
Surrounding Space ◽  
Isolation Device ◽  
Friction Pendulum ◽  
Isolation Performance

This paper describes the results of the response analysis and the experimental tests on the newly developed earthquake isolation system based on the theory of friction pendulum. In Japan, many types of earthquake isolation device or system have been developed and utilized to protect computers, precision equipments and important works of art from the severe seismic attacks. Although the performance of isolation of the each every one of the systems is sufficient, cost of the system is considered generally higher than the user expected and the system requires enough surrounding space to obtain adequate isolation performance. When applying the isolation device to the objects such as display cabinets in museum, computer server racks, bookshelves in library and vending machines which are generally placed adjacent to the wall, it is desirable to set them as closer to the behind wall as possible without decreasing their performance of isolation very much. The friction pendulum type isolation device with poly-curvature has been developed to satisfy these requirements, and the response analysis and the shake table tests have been carried out to investigate the performance of the system.

Shape Optimized Heliostats Using a Tailored Stiffness Approach

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Li Meng ◽  
Zheng You ◽  
A. F. M. Arif ◽  
Steven Dubowsky
Keyword(s):  
Low Cost ◽  
Spot Size ◽  
Substantial Improvement ◽  
Analytical Models ◽  
Element Analysis ◽  
Optical Efficiency ◽  
Honeycomb Sandwich ◽  
Stiffness Profile ◽  
Optical Ray Tracing ◽  
The Ideal

In central receiver systems, the ideal reflective shape of a heliostat is a section of a paraboloid that adapting with the sun's angle and the mirror's location in the field. Deviation from this shape leads to optical astigmatism that increases the spot size on the receiver aperture, which eventually causes higher energy loss and lower conversion efficiency. However, it is challenging to implement the ideal shape by conventional design and manufacturing methods. In this paper, a novel compliant heliostat design methodology is proposed. By tailoring the two dimensional stiffness profile of a square plate, the paraboloid shape can be formed by a simple, low-cost mechanism with concentrated moment loads on the corners of the plate. The static optimized shapes, which can be easily realized by adjusting the loads according to the locations during heliostat assembly on the site, are suggested as approximations of the ideal shapes. Analytical models were developed in detail for the methodology. Numerical analysis consists of finite element analysis, optical ray tracing, and optimization. The numerical results illustrate that the performance of the shape optimized heliostats using tailored stiffness approach is close to the ideal shapes, providing substantial improvement in optical efficiency and reduction in spot size comparing to the flat mirrors. Furthermore, experiments on a prototype heliostat mechanism with a honeycomb-sandwich panel were conducted to validate the effectiveness of this low-cost shaping approach.

Failure Conditions from Push-Out Tests of a Steel-Concrete Joint: Experimental Results

2011 ◽  
Vol 488-489 ◽  
pp. 714-717 ◽  
Author(s):  
Peter Helincks ◽  
Wouter de Corte ◽  
Jan Klusák ◽  
Stanislav Seitl ◽  
Veerle Boel ◽  
...  
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Experimental Tests ◽  
Experimental Results ◽  
Steel Plates ◽  
Element Analysis ◽  
Concrete Core ◽  
Concrete Joints ◽  
Failure Conditions ◽  
Push Out

Steel-concrete joints can suffer from premature fail due to inadequate shear bond between the two surfaces. In this paper the shear bond strength between steel and self-compacting concrete (SCC) without mechanical shear connectors is evaluated through push-out tests. The test samples consist of two sandblasted steel plates (10 and 6 mm) and a concrete core, with connection between steel and concrete obtained by a 2-component epoxy resin, gritted with granulates. During the tests, the ultimate shear force is recorded as well as the slip between steel and concrete. All test members exhibited a concrete - adhesive failure, and indicate nominal shear bond stresses between 2.20 and 4.22 MPa. In addition, a substantial difference in measured shear bond stresses is found between the 6 and 10 mm steel plates, indicating unwanted secondary effects with the 6 mm plates. During testing, maximum slip values between 0.02 and 0.05 mm are recorded. In addition to the experimental tests, shear stress distribution in the epoxy – concrete interface is examined by finite element analysis (FEA). In this way, a non-uniform stress distribution between steel and concrete is found with the maximum shear value about 2.5 times higher than the nominal shear stress value. The FEA combined with the experimental results provide a reasonable understanding of the shear induced failure conditions at a steel-concrete joint, and create test data for a fracture mechanics approach.

scholarly journals Experimental Tests and Analytical Modelling of a Scaled Isolated Structure on Sliding and Elastomeric Bearings

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Fabio Mazza ◽  
Alfonso Vulcano
Keyword(s):  
Experimental Tests ◽  
Shaking Table ◽  
Analytical Models ◽  
Dynamic Tests ◽  
Sliding Bearings ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Fixed Base ◽  
The University ◽  
Base Structure

The main purpose of this study, which was conducted within the framework of a DPC-ReLUIS research project, was to investigate the behaviour of a scaled isolated structure equipped with an in-parallel combination of steel-PTFE sliding bearings and elastomeric bearings (HDRBs). For this purpose, dynamic tests on shaking table were carried out at the Laboratory of the Department of Structures for Engineering and Architecture of the University of Naples Federico II, Italy. An available prototype steel framed structure was used as a superstructure. A further objective of this study was to evaluate the reliability of different analytical models of the isolation system, commonly used, in order to adequately simulate the dynamic response of the isolated structure. The effectiveness of the isolation system was evaluated comparing the experimental response of the isolated structure with the numerical response of the fixed-base structure.

Multi-Scale Approach towards Groningen Masonry and Induced Seismicity

2017 ◽  
Vol 747 ◽  
pp. 653-661 ◽  
Author(s):  
Jan G. Rots ◽  
Francesco Messali ◽  
Rita Esposito ◽  
Valentina Mariani ◽  
Samira Jafari
Keyword(s):  
Induced Seismicity ◽  
Large Scale ◽  
Numerical Models ◽  
Experimental Tests ◽  
Lessons Learned ◽  
Analytical Models ◽  
Structural Level ◽  
Building Stock ◽  
Element Analysis ◽  
Existing Building

In the last years, the induced seismicity in the northern part of the Netherlands has considerably increased. The existing building stock was not designed for seismic loading, and it is characterised by very slender walls, limited cooperation between walls and floors, and use of cavity walls. As a consequence, the validation of analytical and numerical models for the assessment of unreinforced masonry buildings and the characterisation of the masonry at both material and structural level have become of great importance. An extensive large-scale testing program was performed at the Delft University of Technology in 2015 to create benchmarks for the validation of the numerical and analytical models. The attention was mainly devoted to a terraced house typology, which was widely adopted for housing in the period 1960-1980, and focused on the characterisation of the typology at various levels: material, connection, component and assemblage level. The experimental tests at component and assemblage levels were also reproduced by nonlinear finite element analysis, validated and calibrated against the data available from the testing campaign at material level. In this paper, an overview description of performed experiments and numerical analyses is provided; specific devotion is given to the main outcomes of the campaign and to the lessons learned by the experimental evidences for improving the numerical models.

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