Experimental testing and design of BRB with bolted and pinned connections

2014 ◽  
Vol 47 (4) ◽  
pp. 264-274 ◽  
Author(s):  
Stefan Wijanto ◽  
G. Charles Clifton
Keyword(s):  
New Zealand ◽  
Experimental Testing ◽  
Design Procedure ◽  
Hysteresis Loops ◽  
Experimental Tests ◽  
Principal Characteristic ◽  
Procedural Modification ◽  
Reliable Design ◽  
Pinned Connections ◽  
Brb System

The recent series of damaging earthquakes in Christchurch, New Zealand has encouraged greater recognition of the post-earthquake economic impacts on New Zealand society and higher emphasis on low-damage earthquake resisting systems. Braced frames incorporating Buckling Restrained Braces (BRB) are seen as a significant contender for such a system. This research project focuses on the development of a reliable design procedure and detailing requirements for a generic BRB system. To gauge the performance of the designed system and to ascertain the reliability of the developed procedure, a series of static and dynamic sub-assemblage tests on the BRB frame with two different brace connection configurations were performed. The results are presented and discussed herein. The experimental tests generated stable and near symmetrical hysteresis loops, which is a principal characteristic of a well performing BRB system, albeit with the occurrence of slack in the connections. The experimental test results shows that several improvements need to be made to the proposed design procedure and detailing as outlined throughout the paper; especially the procedural modification to prevent slack from occurring in the two different connection systems. It is envisaged that applications will typically involve use of proprietary braces, however these need to be applied in accordance with the New Zealand design procedure; and determining the appropriate procedure was a key part of this project.

On-Site Experimental Testing to Study the Vibration of Composite Floors

2014 ◽  
Vol 601 ◽  
pp. 231-234
Author(s):  
Cristian Lucian Ghindea ◽  
Dan Cretu ◽  
Monica Popescu ◽  
Radu Cruciat ◽  
Elena Tulei
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Testing ◽  
Concrete Slab ◽  
Human Perception ◽  
Experimental Tests ◽  
International Standards ◽  
Structural Element ◽  
Element Analysis ◽  
Floor Slabs ◽  
Composite Floors

As a general trend, in order to reduce material consumption or to reduce the mass of the structures, composite floor slabs solutions are used to achieve large spans floor slabs. This solutions led to floors sensitive to vibrations induced generally by human activities. As a verification of the design concepts of the composite floors, usually, it is recommended a further examination of the floor after completion by experimental tests. Although the experimental values of the dynamic response of the floor are uniquely determined, the processing can take two directions of evaluation. The first direction consist in determining the dynamic characteristics of the floor and their comparison with the design values. Another way that can be followed in the processing of the experimental results is to consider the human perception and comfort to the vibration on floors. The paper aims to present a case study on a composite floor, with steel beams and concrete slab, tested on-site. Both aspects of data processing are analyzed, in terms of the structural element, and in terms of the effect on human perception and comfort. Experimentally obtained values for the dynamic characteristics of the floor are compared with numerical values from finite element analysis, while the second type of characteristic values are compared with various human comfort threshold values found in international standards.

New Zealand translocations: theory and practice

1995 ◽  
Vol 2 (1) ◽  
pp. 39 ◽  
Author(s):  
Doug P. Armstong ◽  
Ian G. McLean
Keyword(s):  
Population Dynamics ◽  
New Zealand ◽  
Experimental Tests ◽  
Theory And Practice ◽  
Habitat Requirements ◽  
Metapopulation Dynamics ◽  
Behavioural Adaptation ◽  
New Locations ◽  
History Of ◽  
Tests Of Hypotheses

One of the most common tools in New Zealand conservation is to translocate species to new locations. There have now been over 400 translocations done for conservation reasons, mainly involving terrestrial birds. Most translocations have been done strictly as management exercises, with little or no reference to theory. Nevertheless, translocations always involve some underlying theory, given that people must inevitably choose among a range of potential translocation strategies. We review theory relevant to translocations in the following areas: habitat requirements, susceptibility to predation, behavioural adaptation, population dynamics, genetics, metapopulation dynamics, and community ecology. For each area we review and evaluate the models that seem to underpin translocation strategies used in New Zealand. We report experiments testing some of these models, but note that theory underlying translocation strategies is largely untested despite a long history of translocations. We conclude by suggesting key areas for research, both theoretical and empirical. We particularly recommend that translocations be designed as experimental tests of hypotheses whenever possible.

scholarly journals Flexural behavior of sandwich panels with cellular wood, plywood stiffener/foam and thermoplastic composite core

2017 ◽  
Vol 21 (2) ◽  
pp. 784-805 ◽  
Author(s):  
Edgars Labans ◽  
Kaspars Kalnins ◽  
Chiara Bisagni
Keyword(s):  
Mechanical Performance ◽  
Sandwich Panels ◽  
Experimental Tests ◽  
Design Tool ◽  
Thermoplastic Composite ◽  
Flexural Behavior ◽  
Four Point Bending ◽  
Reliable Design ◽  
Sufficient Strength ◽  
Core Part

A series of experimental tests have been carried out on three types of novel sandwich panels mainly designed for application in lightweight mobile housing. Two types of the panels are manufactured entirely from wood-based materials while the third one presents a combination of plywood for surfaces and corrugated thermoplastic composite as a core part. All sandwich panels are designed to allow rapid one-shot manufacturing. Mechanical performance has been evaluated in four-point bending comparing the data to the reference plywood board. Additionally, finite element simulations were performed to evaluate global behavior, stress distribution and provide the basis for a reliable design tool. Obtained results show sufficient mechanical characteristics suitable for floor and wall units. Compared to a solid plywood board, sandwich alternative can reach up to 42% higher specific stiffness, at the same time maintaining sufficient strength characteristics.

Design of a Force Feedback Chatter Control System

1972 ◽  
Vol 94 (1) ◽  
pp. 5-10 ◽  
Author(s):  
C. Nachtigal
Keyword(s):  
Machine Tool ◽  
Frequency Domain ◽  
Transient Response ◽  
Force Feedback ◽  
Design Procedure ◽  
Experimental Tests ◽  
Work Piece ◽  
Regenerative Chatter ◽  
Chatter Control ◽  
The Stability

The analysis of machine tool chatter from frequency domain considerations is generally accepted as a valid representation of the regenerative chatter phenomenon. However, active control of regenerative chatter is still in its embryonic stage. It was established in reference [2] that a measurement of the cutting force could be effectively used in conjunction with a controller and a tool position servo system to increase the stability of an engine lathe and to improve its transient response. This paper presents the design basis for such a system, including both analytical and experimental considerations. The design procedure stems from a real part stability criterion based on the work by Merritt [1]. Because of the unknown variability in the dynamics of a machine tool system, the controller parameters were chosen to accomodate some mismatch between structure and tool servo dynamics. Experimental tests to determine the stability zone of the controlled machine tool system qualitatively confirmed the analytical design results. The experimental results were consistent in that the transient response tests confirmed the frequency domain stability tests. It was also demonstrated experimentally that the equivalent static stiffness of a flexible work-piece system could be substantially increased.

scholarly journals A New Multiparameter Model for Multiaxial Fatigue Life Prediction of Rubber Materials

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1194
Author(s):  
Rafael Tobajas ◽  
Daniel Elduque ◽  
Elena Ibarz ◽  
Carlos Javierre ◽  
Luis Gracia
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Experimental Testing ◽  
Experimental Tests ◽  
Relevant Information ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Proposed Model ◽  
Predicted Values

Most of the mechanical components manufactured in rubber materials experience fluctuating loads, which cause material fatigue, significantly reducing their life. Different models have been used to approach this problem. However, most of them just provide life prediction only valid for each of the specific studied material and type of specimen used for the experimental testing. This work focuses on the development of a new generalized model of multiaxial fatigue for rubber materials, introducing a multiparameter variable to improve fatigue life prediction by considering simultaneously relevant information concerning stresses, strains, and strain energies. The model is verified through its correlation with several published fatigue tests for different rubber materials. The proposed model has been compared with more than 20 different parameters used in the specialized literature, calculating the value of the R2 coefficient by comparing the predicted values of every model, with the experimental ones. The obtained results show a significant improvement in the fatigue life prediction. The proposed model does not aim to be a universal and definitive approach for elastomer fatigue, but it provides a reliable general tool that can be used for processing data obtained from experimental tests carried out under different conditions.

scholarly journals Framework for Fast Experimental Testing of Autonomous Navigation Algorithms

2019 ◽  
Vol 9 (10) ◽  
pp. 1997 ◽  
Author(s):  
Miguel Á. Muñoz–Bañón ◽  
Iván del Pino ◽  
Francisco A. Candelas ◽  
Fernando Torres
Keyword(s):  
Autonomous Navigation ◽  
Mobile Robotics ◽  
Experimental Testing ◽  
Autonomous Systems ◽  
Experimental Tests ◽  
Basic Structure ◽  
Satellite System ◽  
Outdoor Environments ◽  
Global Navigation Satellite ◽  
Abstraction Levels

Research in mobile robotics requires fully operative autonomous systems to test and compare algorithms in real-world conditions. However, the implementation of such systems remains to be a highly time-consuming process. In this work, we present an robot operating system (ROS)-based navigation framework that allows the generation of new autonomous navigation applications in a fast and simple way. Our framework provides a powerful basic structure based on abstraction levels that ease the implementation of minimal solutions with all the functionalities required to implement a whole autonomous system. This approach helps to keep the focus in any sub-problem of interest (i.g. localization or control) while permitting to carry out experimental tests in the context of a complete application. To show the validity of the proposed framework we implement an autonomous navigation system for a ground robot using a localization module that fuses global navigation satellite system (GNSS) positioning and Monte Carlo localization by means of a Kalman filter. Experimental tests are performed in two different outdoor environments, over more than twenty kilometers. All the developed software is available in a GitHub repository.

Experimental Tests of I Profile Made from UHPC Reinforced with Textile Glass Fibres

2016 ◽  
Vol 249 ◽  
pp. 261-266
Author(s):  
Tomáš Bittner ◽  
Petr Bouška ◽  
Šárka Nenadálová ◽  
Milan Rydval ◽  
David Čítek
Keyword(s):  
Experimental Testing ◽  
Experimental Tests ◽  
Loading Capacity ◽  
Test Results ◽  
Glass Fibres ◽  
Material Characteristics ◽  
Recorded Data ◽  
Glass Reinforcement ◽  
Metal Wires ◽  
3D Profile

This abstract is summarizing production and subsequent experimental testing of 3D profile of the symmetrical I shape concrete from UHPC matrix and reinforced with textile glass fibres. Upper and bottom covering strips of this profile are at the outside fibres reinforced with textile glass reinforcement. Position of this reinforcement is fixed in the distance of about 3 mm from outside fibres and is connected with reinforcement of the profile stem located in its axis. Such prepared beams were tested with four-point flexure evenly loaded until fracture. Course of the measurement was continuously recorded by the automatic logger, where mostly increase of the force in relation to deflection in the middle of the span and change of position of supports were recorded. From the recorded data were prepared graphic outputs compared with the same experiments performed on I profile which is not reinforced, i.e. only UHPC matrix, and for comparison also on the profile made from UHPC matrix with use of metal wires. In the conclusion were compared achieved test results. Mainly suitability and loading capacity of individual beam types was compared. Within the experiment were performed supporting tests based on which were determined material characteristics of tested matrix and textile glass reinforcement. Tests were performed in the Klokner Institute within solution of the grant project GACŘ 13-12676S.

An Elaborate Data Set for Mechanical Characterization of the Foot

2008 ◽  
Author(s):  
Pavana Sirimamilla ◽  
Ahmet Erdemir ◽  
Antonie J. van den Bogert ◽  
Jason P. Halloran
Keyword(s):  
Mechanical Response ◽  
Experimental Testing ◽  
Experimental Tests ◽  
Shear Loading ◽  
Data Set ◽  
Material Response ◽  
Heel Pad ◽  
Biaxial Tests

Experimental testing of cadaver specimens is a useful means to quantify structural and material response of tissue and passive joint properties against applied loading[1,4]. Very often, specific material response (i.e., stress-strain behavior of a ligament or plantar tissue) has been the goal of experimental testing and is accomplished with uniaxial and/or biaxial tests of prepared tissue specimens with uniform geometries[2,5]. Material properties can then be calculated directly and if testing data involves individual sets of multiple loading modes (e.g. compression only, shear only, volumetric) an accurate representation of the global response of the specimen may be possible. In foot biomechanics, however, it is practically impossible to perform isolated mechanical testing in this manner. The structural response, therefore the stiffness characteristics, of the foot have been quantified, usually using a dominant loading mode: e.g., whole foot compression [6], heel pad indentation [3]. This approach ignores the complexity of most in vivo loading conditions, in which whole foot deformation involves interactions between compression, shear (e.g. heel pad) and tension (e.g. ligaments). Therefore, the purpose of this study was to quantify the mechanical response of a cadaver foot specimen subjected to compression and anterior-posterior (AP) shear loading of isolated heel and forefoot regions as well as whole foot compression. Results from the experimental tests represent a novel methodology to quantify a complete structural biomechanical response. Combined with medical imaging, followed by inverse finite element (FE) analysis, the data may also serve for material characterization of foot tissue.

scholarly journals Fresh and Hardened Properties of Extrusion-Based 3D-Printed Cementitious Materials: A Review

2020 ◽  
Vol 12 (14) ◽  
pp. 5628
Author(s):  
Zhanzhao Li ◽  
Maryam Hojati ◽  
Zhengyu Wu ◽  
Jonathon Piasente ◽  
Negar Ashrafi ◽  
...  
Keyword(s):  
3D Printing ◽  
Experimental Testing ◽  
Design Procedure ◽  
Cementitious Materials ◽  
Material Point ◽  
Point Of View ◽  
Open Time ◽  
Potential Benefits ◽  
3D Printed ◽  
Hardened Properties

3D-printing of cementitious materials is an innovative construction approach with which building elements can be constructed without the use of formwork. Despite potential benefits in the construction industry, it introduces various engineering challenges from the material point of view. This paper reviews the properties of extrusion-based 3D-printed cementitious materials in both fresh and hardened states. Four main properties of fresh-state printing materials are addressed: flowability, extrudability, buildability, and open time, along with hardened properties, including density, compressive strength, flexural strength, tensile bond strength, shrinkage, and cracking. Experimental testing and effective factors of each property are covered, and a mix design procedure is proposed. The main objective of this paper is to provide an overview of the recent development in 3D-printing of cementitious materials and to identify the research gaps that need further investigation.

scholarly journals Performance Evaluation of Multi-UAV Network Applied to Scanning Rocket Impact Area

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4895
Author(s):  
Maurício R. Silva ◽  
Elitelma S. Souza ◽  
Pablo J. Alsina ◽  
Deyvid L. Leite ◽  
Mateus R. Morais ◽  
...  
Keyword(s):  
Communication Network ◽  
Communication Networks ◽  
Network Architecture ◽  
Design Procedure ◽  
Data Communication ◽  
Experimental Tests ◽  
Network Nodes ◽  
Communication Links ◽  
Impact Area ◽  
Multi Uav

This paper presents a communication network for a squadron of unmanned aerial vehicles (UAVs) to be used in the scanning rocket impact area for Barreira do Inferno Launch Center—CLBI (Rio Grande do Norte, Brazil), aiming at detecting intruder boats. The main features of communication networks associated with multi-UAV systems are presented. This system sends information through Wireless Sensor Networks (WSN). After comparing and analyzing area scanning strategies, it presents the specification of a data communication network architecture for a squadron of UAVs within a sensor network using XBee Pro 900HP S3B modules. A brief description is made about the initial information from the construction of the system. The embedded hardware and the design procedure of a dedicated communication antenna to the XBee modules are presented. In order to evaluate the performance of the proposed architecture in terms of robustness and reliability, a set of experimental tests in different communication scenarios is carried out. Network management software is employed to measure the throughput, packet loss and other performance indicators in the communication links between the different network nodes. Experimental results allow verifying the quality and performance of the network nodes, as well as the reliability of the communication links, assessing signal received quality, range and latency.

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