scholarly journals Structural Timber Connections with Dowel-Type Fasteners and Nut-Washer Fixings: Mechanical Characterization and Contribution to the Rope Effect

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 242
Author(s):  
Manuel Domínguez ◽  
Jose G. Fueyo ◽  
Alberto Villarino ◽  
Natividad Anton
Keyword(s):  
Flat Surface ◽  
Experimental Tests ◽  
Know How ◽  
Multiple Variables ◽  
Timber Joints ◽  
Joint Displacement ◽  
Timber Connections ◽  
External Loads ◽  
Force Displacement ◽  
Actual Size

Dowel-type fasteners are one of the most used type of connections in timber joints. Its design follows the equations included in the Eurocode 5. The problem with these equations is that they do not adequately contemplate the resistive capacity increase of these joints, when using configurations which provoke the so-called rope effect. This effect appears when using threaded surface dowels instead of flat surface dowels, expansion kits or nut-washer fixings at the end of the dowel. The standards consider this increase through a constant value, which is a poor approximation, because it is clearly variable, depending on the joint displacement and because is much bigger, especially when using nut-washer fixings. It is also very important because of the rope effect trigger interesting mechanisms that avoids fragile failures without warning of the joints. For these reasons, it is essential to know how these configurations work, how they help the joint to resist the external loads and how much is the increase resistance capacity in relationship with the joint displacement. The methods used to address these issues consisted of a campaign of experimental tests using actual size specimens with flat surface dowels, threaded surface dowels and dowels with washer-nut fixings at their ends. The resistance capacity results obtained in all the cases has been compared with the values that will come using the equations in the standards. After the tests the specimens were cut to analyze the timber crushings, their widths, the positions and level of plasticizations suffer in the steel dowels and in the washer-nut fixings and the angle formed in the dowel plastic hinges. With all this information the failure mode suffered by the joints has been identified and compared with the ones that the standards predict. The results for the size materials and types of joints studied shows that the crush width average values go from 20 mm with flat surface dowels, to 24 mm in threaded to 32 mm in threaded with washer-nut fixings. The rope effect force/displacement goes from 100 N/m in threaded surface dowels to 500 N/m in threaded with washer-nut fixings. Finally, the load capacities are on average 290% higher those indicated in the standard. The main conclusion is that the rope effect force should be considered in the standards in more detail as a function of multiple variables, especially the displacement of the joint.

Boats That Fly

1922 ◽  
Vol 26 (135) ◽  
pp. 108-114
Author(s):  
D. C. M. Hume
Keyword(s):  
Flat Surface ◽  
Lewis Carroll ◽  
Know How ◽  
The Poor ◽  
Poor White ◽  
Looking Glass

You all know those jolly words from “ Alice's Adventures through the Looking Glass,” and in a measure we are about to push our way through the melting mirror of hearsay to the strange world of wonderful facts, where boats fly, and men think nothing of the sort of ascent that blew the breath out of the poor White King when he received his first dusting in the air. We will talk, you and I, of shoes for aircraft—ships that fly and sealing wax that guards the secrets that have made the British seaplane the greatest example of its kind in all the wide world.First of all you would like to find out, I know, how aircraft manage to fly at all.You can find that out easily. Take a large box lid or other flat surface, hold it up vertically before you and run across the room with it.“ The time has come, ” the Walrus said,“ To talk of many things ;Of shoes and ships and sealing wax,Of cabbages and kings. ”Lewis Carroll

Adapted Bouc-Wen Analytical Model for Romanian SERB-C Seismic Dampers Used in Buildings Protection System

2016 ◽  
Vol 823 ◽  
pp. 91-94 ◽  
Author(s):  
Adriana Ionescu ◽  
Cristian Burada ◽  
Mihai Negru
Keyword(s):  
Mathematical Model ◽  
Computational Simulation ◽  
Experimental Tests ◽  
Protection System ◽  
Hysteretic Model ◽  
Specific Adaptation ◽  
Analytical Simulation ◽  
The Mathematical Model ◽  
Force Displacement ◽  
Unusual Shape

In this paper is presented a new mathematical model which is intended to simulate the hysteretic phenomenon of SERB-C Romanian friction device for damping and dissipation of earthquake energy used for buildings. These devices have unusual shape of force-displacement loop which can be simulated with our new model which represents a specific adaptation of the well known Bouc-Wen hysteretic model. The purpose of this analytical simulation is to determine a relation for the hysteretic loop which was obtained by experimental tests performed by the authors. The mathematical model presented in this paper can be used in computational simulation of a building protected with these types of devices, in order to determine the anti-seismic performances of a Romanian friction building protection system.

Experimental study of the nature of the load distribution on the turns of the thread of the planetary roller-screw mechanism

2019 ◽  
Author(s):  
O.A. Ryakhovskiy ◽  
A.S. Marokhin ◽  
A.N. Vorobyev ◽  
O.A. Khachirova
Keyword(s):  
Load Distribution ◽  
Axial Load ◽  
Flat Surface ◽  
Experimental Setup ◽  
Feed Drives ◽  
The Press ◽  
Roller Screw ◽  
Screw Mechanism ◽  
Force Displacement ◽  
Made In

The article considers the effect of axial load on the turns of the thread of the planetary roller-screw converter of rotational motion into translational one. For this purpose an experimental setup was made in which the nut lies end-face on the flat surface of the press, a screw is screwed into it. The force is applied to the screw through a ball to distribute the load uniformly. The design of the machine for compression measurement allows automatic recording the axial mutual movement of tested mechanism parts when the loading force changes. Contact and displacement occur when the loading force reaches 300 N. The results are obtained in the form of a "force – displacement" graph. In the course of the experiment, the influence of step error on the uniformity of the contacts of the turns of the mating parts of the planetary roller-screw mechanism was checked. The results of the experiment are analyzed, the influence of inaccuracy of manufacturing thread of planetary roller-screw mechanism parts on its capacity for use in feed drives of various machines is considered.

A Performance Study of Self-Piercing Riveting of Aluminum and Copper Alloy Sheets

2013 ◽  
Vol 734-737 ◽  
pp. 2460-2464 ◽  
Author(s):  
Cheng Jiang Deng ◽  
Xiao Cong He ◽  
Bao Ying Xing
Keyword(s):  
Copper Alloy ◽  
Experimental Tests ◽  
Type Specimen ◽  
Static Strength ◽  
Alloy Sheet ◽  
Performance Study ◽  
Type Specimens ◽  
Lap Shear ◽  
Shear Type ◽  
Force Displacement

This paper studied the performance of self-piercing riveting (SPR) of aluminum and copper alloy sheet. The SPR process of two copper alloy sheets was analyzed by experimental tests and finite elements stimulation, and good agreements between the simulations and test results of SPR process were obtained. Two different specimen geometries were adopted in experiment: a lap-shear type specimen and a T type specimen. The influence of combination of different materials on the static strength of SPR joints were studied through the tensile-shear and peeling experiments, and the strength of the SPR joints were evaluated by the force-displacement curves of two type specimens. The failure mechanisms corresponding to the static strength were also discussed. On the other hand, the engineering stress - strain curves of two materials have also been studied roughly. These results could provide designer engineers with some application messages of SPR.

Static and Dynamic Analysis of Deformable Fractal Surface in Contact With Rigid Flat

2021 ◽  
pp. 141-174
Author(s):  
Tamonash Jana ◽  
Anirban Mitra ◽  
Prasanta Sahoo
Keyword(s):  
Dynamic Analysis ◽  
Rough Surface ◽  
Flat Surface ◽  
Contact System ◽  
Fractal Surface ◽  
Response Curves ◽  
Fractal Rough Surface ◽  
Static And Dynamic Analysis ◽  
Force Contact ◽  
Force Displacement

The chapter consists of static and dynamic analyses of a fractal rough surface in contact with a rigid flat. The fractal surface is constructed using modified Weierstrass-Mandelbrot function. A rigid flat surface touches the topmost point of the rough surface, which moves towards the rough surface and deforms it. Different contact parameters (e.g., contact force, contact area, contact stress, etc. for varying fractal and material properties are obtained through finite element based static analysis. A parameter denoting the degree of nonlinearity of the contact system is extracted from the force-displacement plot of the surface. This parameter is utilized to explain the dynamic behaviour of the fractal surface which vibrates under the influence of the externally excited rigid flat surface. The dynamic analysis of the contact system is carried out by modelling the contact interface as a single degree of freedom (SDOF) spring-mass-damper system. The dynamic behavior of the system is investigated in terms of frequency response curves, time-displacement plots, and phase plots.

Multiaxial Fatigue Evaluation of ST52-3N Structural Steel

2010 ◽  
Vol 452-453 ◽  
pp. 41-44 ◽  
Author(s):  
Belen Moreno ◽  
Pablo Lopez-Crespo ◽  
Antonio González-Herrera ◽  
Jose Zapatero
Keyword(s):  
Experimental Data ◽  
Residual Stresses ◽  
Structural Steel ◽  
Experimental Tests ◽  
Multiaxial Fatigue ◽  
Mechanical Components ◽  
Fatigue Evaluation ◽  
Monotonic Properties ◽  
External Loads ◽  
Axial Fatigue

Many mechanical components are subjected to multiaxial fatigue. These conditions are typically coming from external loads, the geometry of the component and/or residual stresses. However the majority of experimental data available in the literature are focused on the simpler uni-axial fatigue problem. The present work describes a series of experimental tests conducted to characterise in a comprehensive way the multiaxial behaviour of a ST52-3N structural steel. First, the monotonic properties of the steel were obtained experimentally. Then cyclic properties were also measured both in the longitudinal and torsional axes. Finally another series of tests were carried out to study the multiaxial response of the material. Both in-phase (proportional) and out-of-phase (non proportional) loadings were employed, thus providing a complete database for improving current models which describe the multiaxial behaviour of materials.

Bond Models for FRP Bars Anchorage in Concrete Slabs under Fire

2011 ◽  
Vol 82 ◽  
pp. 533-538 ◽  
Author(s):  
Emidio Nigro ◽  
Antonio Bilotta ◽  
Giuseppe Cefarelli ◽  
Gaetano Manfredi ◽  
Edoardo Cosenza
Keyword(s):  
Experimental Tests ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Concrete Slabs ◽  
Concrete Members ◽  
Reinforced Polymer ◽  
In Fire ◽  
External Loads ◽  
Frp Bars ◽  
Concrete Interface

Experimental tests were recently performed to evaluate resistance and deformability of nine concrete slabs reinforced with Fiber Reinforced Polymer (FRP) bars in fire situation by varying (a) external loads in the range of the service loads, (b) concrete cover in the range of usual values (30-50mm), (c) bar end shape (straight or bent) and its length at the end of the concrete members, namely in the zone not directly exposed to fire (250-500mm). Experimental results showed the importance of concrete cover in the zone directly exposed to fire for the protection provided to FRP bars, due to its low thermal conductivity. Moreover, the length of the FRP bars in the zone of slab not directly exposed to fire and its shape at the end of the members was crucial to ensures slab resistance once the resin softening reduced the adhesion at the FRP-concrete interface in the fire exposed zone of slab. In particular the anchorage obtained simply by bending bars at the end of member in a short zone (250mm) allowed attaining a good structural behavior in case of fire equivalent to that showed by slabs characterized by a large anchoring length (500mm). Tests results are briefly compared and discussed in this paper, whereas the behavior of the bar anchorage is carefully examined based on both the results of numerical thermal analysis and the predictions of a bond theoretical model adjusted for fire situation.

scholarly journals Methodology to Calibrate the Dissection Properties of Aorta Layers from Two Sets of Experimental Measurements

Mathematics ◽  
2021 ◽  
Vol 9 (14) ◽  
pp. 1593
Author(s):  
Itziar Ríos-Ruiz ◽  
Myriam Cilla ◽  
Miguel A. Martínez ◽  
Estefanía Peña
Keyword(s):  
Aortic Dissection ◽  
Computational Models ◽  
Fatal Outcome ◽  
Computational Modelling ◽  
Experimental Tests ◽  
Material Model ◽  
Aneurysm Rupture ◽  
Aortic Tissue ◽  
Numerical Tools ◽  
Force Displacement

Aortic dissection is a prevalent cardiovascular pathology that can have a fatal outcome. However, the mechanisms that trigger this disease and the mechanics of its progression are not fully understood. Computational models can help understand these issues, but they need a proper characterisation of the tissues. Therefore, we propose a methodology to obtain the dissection parameters of all layers in aortic tissue via the computational modelling of two different delamination tests: the peel and mixed tests. Both experimental tests have been performed in specimens of porcine aorta, where the intima-media and media-adventitia interfaces, as well as the medial layer, were dissected. These two tests have been modelled using a cohesive zone formulation for the separating interface and a hyperelastic anisotropic material model via an implicit static analysis. The dissection properties of each interface have been calibrated by reproducing the force-displacement curves obtained in the experimental tests. The values of peak and mean force of the experiments were fitted with an error below 10%. With this methodology, we intend to contribute to the development of reliable numerical tools for simulating aortic dissection and aortic aneurysm rupture.

scholarly journals MANNGA: A Robust Method for Gap Filling Meteorological Data

2019 ◽  
Vol 34 (2) ◽  
pp. 315-323
Author(s):  
Thiago Meirelles Ventura ◽  
Claudia Aparecida Martins ◽  
Josiel Maimone de Figueiredo ◽  
Allan Gonçalves de Oliveira ◽  
Johnata Rodrigo Pinheiro Montanher
Keyword(s):  
Meteorological Data ◽  
Experimental Tests ◽  
High Accuracy ◽  
Meteorological Variables ◽  
Gap Filling ◽  
Main Approach ◽  
Java Programming ◽  
The Core ◽  
Different Types ◽  
Multiple Variables

Abstract This paper presents Mannga (Multiple variables with Artificial Neural Network and Genetic Algorithm), a method designed for gap filling meteorological data. The main approach is to estimate the missing data based on values of other meteorological variables measured at the same time in the same local, since the meteorological variables are strongly related. Experimental tests showed the performance of Mannga compared with other two methods typically used by researches in this area. Good results were achieved, with high accuracy even for sequential failures, which is a big challenge for researchers. The core advantages of Mannga are the flexibility of handling different types of meteorological data, the ability of select the best variables to assist the gap filling and the capacity to deal with sequential failures. Moreover, the method is available to public use with the Java programming language.

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