Search results for "stiffne"

Method for estimating combined controller, joint and link stiffnesses of an industrial robot

2014

In this paper a new combined local/global approach for estimating the combined stiffnesses of joints in anthropomorphic robots is presented. The stiffness of each joint is a combination of several effects: i) stiffness of the links, ii) stiffness of joint bearings and gears and iii) stiffness of the position control loops given by the individual axis controller gains in the controller software. Experimental results are presented for an ABB IRB6600 industrial robot using measurements from a FARO Xi laser tracker and an ATI Omega160 force/torque sensor. The results show that there is a significant variation in stiffness among the individual joints of the robot and that the stiffnesses of the …

The metabolic syndrome-arterial stiffness relationship in patients with ischaemic stroke: role of inflammation

2008

THE INFLUENCE OF TOOL STIFFNESS OF THE LIFETIME OF THE INSERTS IN INTERRUPTED CUTTING OPERATIONS

1989

ABSTRACT In the present paper the influence exerted by the stiffness of the tool-workpiece system under working conditions on tool life up to the fracture of carbide inserts in interrupted cutting is investigated. It is shown how, with the increase in compliance of the system, there is a corresponding increase in the average tool life of the insert which is greater the lesser the cutting speed. The results of tests carried out indicate as a possible cause the amount of damage evident in the successive phase of tool engagement with the workpiece. It was observed how, in this phase, the tool, vibrating at the same rate as the toolholder produces alternations in the cutting force. This effect …

Relazione tra stiffness aortica ed uricemia nell'ipertensione arteriosa essenziale

2012

Locking Reconstruction Double Plating of Distal Humeral Fractures: How Many Screws in the Distal Ulnar Column Segment in A3 Fracture Provide Superior…

2009

Objectives: Two 90-degree configurations of locking reconstruction plates with different numbers of screws in the distal ulnar column segment of distal extra-articular humeral fractures with metaphyseal comminution (A3) were biomechanically investigated. Methods: Eight pairs of fresh-frozen human humeri were used. For paired comparison, the humeri were divided into 2 randomized groups. In both groups, double-plate osteosyntheses with locking reconstruction plates were performed in 90-degree configurations. In group 1, the posteriorly placed radial column plate exceeded the capitellum and the ulnar column plate extended into the ulnar sulcus. The ulnar plate was molded around the medial epic…

Strain Measurement on Composites: Effects due to Strain Gauge Misalignment

2008

:  The present work analyses the errors affecting the strains measured by misaligned strain gauges installed on orthotropic-composite laminae. Various analytical relationships are derived showing that, besides the fibre and strain gauge orientations, the misalignment error in unidirectional off-axis orthotropic composite samples depends also on the lamina stiffness properties (E1, E2, ν12, G12). If the fibres are aligned with the loading axis, it is found that the higher Poisson's ratio ν12 is the only elastic property influencing the misalignment error. Experimental results are shown confirming the theoretical predictions.

The role of connectivity in the properties of sedimented materials

2003

Effective-medium theories for both random packings of elastic discs and mats of randomly sedimented elastic fibers can be constructed such that the effective material stiffness depends on the stiffness and geometry of the constituents of the material, and the number density of contacts. It is demonstrated that the number density of contacts together with the geometry of the constituents also determine the porosity of these materials. The simplicity and similar structure of the effective-medium estimates for the properties of these two qualitatively different materials indicate that the number density of contacts may play a similar role in an appropriate effective-medium description of a lar…

Comparison of numerical modelling techniques for impact investigation on a wind turbine blade

2019

Wind turbine blades are exposed to numerous impact risks throughout their lifetimes. The impact risks range from bird collisions during operation to impacts with surrounding structures at the time of transportation and installation. Impact loads on the fibre composite blades can induce several complex, simultaneously interacting and visually undetectable damage modes and have a high potential to reduce the local and global blade stiffness. An assessment of such impact-induced damages is therefore necessary and usually involves high computational costs using numerical procedures, especially when analysing large composite components. To minimise this computational expense, different numerical…

How to define variation of physical properties normal to an undulating one-dimensional object.

2009

One-dimensional flexible objects are abundant in physics, from polymers to vortex lines to defect lines and many more. These objects structure their environment and it is natural to assume that the influence these objects exert on their environment depends on the distance from the line-object. But how should this be defined? We argue here that there is an intrinsic length scale along the undulating line that is a measure of its "stiffness" (i.e., orientational persistence), which yields a natural way of defining the variation of physical properties normal to the undulating line. We exemplify how this normal variation can be determined from a computer simulation for the case of a so-called b…

Can Soft Models Describe Polymer Knots?

2020

Similar to macroscopic ropes and cables, long polymers create knots. We address the fundamental question whether and under which conditions it is possible to describe these intriguing objects with crude models that capture only mesoscale polymer properties. We focus on melts of long polymers which we describe by a model typical for mesoscopic simulations. A worm-like chain model defines the polymer architecture. To describe nonbonded interactions, we deliberately choose a generic "soft" repulsive potential that leads to strongly overlapping monomers and coarse local liquid structure. The soft model is parametrized to accurately reproduce mesoscopic structure and conformations of reference p…