scholarly journals Ductile Behavior of Timber Structures under Strong Dynamic Loads

10.5772/65894 ◽  
2017 ◽  
Author(s):  
Maria Cristina Porcu
Keyword(s):  
Dynamic Loads ◽  
Timber Structures ◽  
Ductile Behavior ◽  
Strong Dynamic

Contribution to robots control with parallel degrees of freedom

Robotica ◽  
1994 ◽  
Vol 12 (6) ◽  
pp. 569-573
Author(s):  
V. Potkonjak ◽  
T. Petrović
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Loads ◽  
Redundant Robot ◽  
One Dimensional ◽  
Control Scheme ◽  
Nonuniform Motion ◽  
Strong Dynamic

SummaryThis paper considers some problems concerning the motion and the control of large robots. The problem arises when highly nonuniform motion is required. It results in too strong dynamic loads and the robot cannot operate successfully. The solution is found in the introduction of redundancy in the form of parallel degrees of freedom. Kinematics of such a system follows the distributed positioning concept. The control scheme is developed for a one-dimensional redundant robot.

Effects of Plasticity on Dynamic Response of Piping Structures

1988 ◽  
Vol 110 (3) ◽  
pp. 263-269 ◽  
Author(s):  
L. Lazzeri
Keyword(s):  
Dynamic Response ◽  
Failure Mechanism ◽  
Dynamic Loads ◽  
Equivalent Damping ◽  
Static And Dynamic Loads ◽  
Ductile Behavior ◽  
Frequency Shifting

The analysis of elastoplastic structures under a combination of static and dynamic loads is examined. It is shown that under the hypothesis of a ductile behavior, progressive distortion is the leading failure mechanism. Procedures are described to compute: (a) the equivalent damping due to hysteretic losses; (b) frequency shifting due to structural softening in the plastic fields; (c) ductility effects on dynamic loads; and (d) ratcheting due to a combination of static and dynamic loads.

Phase Transformation In Ti-6al-4v Alloys

1972 ◽  
Vol 30 ◽  
pp. 584-585
Author(s):  
Shiro Fujishiro
Keyword(s):  
Phase Transformation ◽  
Grain Boundary ◽  
Cryogenic Temperature ◽  
Β Phase ◽  
Heat Treated ◽  
Mixed Microstructure ◽  
Ductile Behavior

The Ti-6 wt.% Al-4 wt.% V commercial alloys have exhibited an improved formability at cryogenic temperature when the alloys were heat-treated prior to the tests. The author was interested in further investigating this unusual ductile behavior which may be associated with the strain-induced transformation or twinning of the a phase, enhanced at lower temperatures. The starting materials, supplied by RMI Co., Niles, Ohio were rolled mill products in the form of 40 mil sheets. The microstructure of the as-received materials contained mainly ellipsoidal α grains measuring between 1 and 5μ. The β phase formed an undefined grain boundary around the a grains. The specimens were homogenized at 1050°C for one hour, followed by aging at 500°C for two hours, and then quenched in water to produce the α/β mixed microstructure.

Study of the dynamics of ТПА 350 automatic mill working stand elements

2020 ◽  
Vol 76 (8) ◽  
pp. 830-840
Author(s):  
S. R. Rakhmanov ◽  
V. V. Povorotnii
Keyword(s):  
Mechanical System ◽  
Dynamic Model ◽  
Maximum Amplitude ◽  
Calculation Scheme ◽  
Dynamic Loads ◽  
Forced Oscillations ◽  
Mass Model ◽  
Automatic Mill ◽  
Hollow Billet ◽  
Oscillation Movement

To form a necessary geometry of a hollow billet to be rolled at a pipe rolling line, stable dynamics of the base equipment of the automatic mill working stand has a practical meaning. Among the forces, acting on its parts and elements, significant by value short-time dynamic loads are the least studied phenomena. These dynamic loads arise during transient interaction of the hollow billet, rollers, mandrel and other mill parts at the forced grip of the hollow billet. Basing of the calculation scheme and dynamic model of the mechanical system of the ТПА 350 automatic mill working stand was accomplished. A mathematical model of dynamics of the system “hollow billet (pipe) – working stand” within accepted calculation scheme and dynamic model of the mechanical system elaborated. Influence of technological load of the rolled hollow billet variation in time was accounted, as well as variation of the mechanical system mass, and rigidity of the ТПА 350 automatic mill working stand. Differential equations of oscillation movement for four-mass model of forked sub-systems of the automatic mill working stand were made up, results of their digital calculation quoted. Dynamic displacement of the stand elements in the inter-roller gap obtained, which enabled to estimate the results of amplitude and frequency characteristics of the branches of the mill rollers setting. It was defined by calculation, that the maximum amplitude of the forced oscillations of elements of the ТПА 350 automatic mill working stand within the inter-roller gap does not exceed 2 mm. It is much higher than the accepted value of adjusting parameters of the deformation center of the ТПА 350 automatic mill. A scheme of comprehensive modernization of the rollers setting in the ТПА 350 automatic mill working stand was proposed. It was shown, that increase of rigidity of rollers setting in the ТПА 350 automatic mill working stand enables to stabilize the amplitude of forced oscillations of the working stand elements within the inter-rollers gap and considerably decrease the induced nonuniform hollow billet wall thickness and increase quality of the rolled pipes at ТПА 350.

A Summary Report on Second World War Activity at Watery Lane, Church Crookham, Hampshire

2019 ◽  
Vol 74 (1) ◽  
pp. 170-176
Author(s):  
Matt Nichol
Keyword(s):  
Second World War ◽  
Late Prehistoric ◽  
Timber Structures ◽  
Summary Report ◽  
World War ◽  
Archaeological Excavation ◽  
Field Boundary ◽  
Development Area ◽  
Five Phases ◽  
Second World

An archaeological excavation of four areas approximately 0.39ha in total, of land at Watery Lane, Church Crookham, Hampshire, was undertaken by Cotswold Archaeology in November and December 2016. It followed the recording of two Pill Boxes and a trial trench evaluation of a wider development area. In all four areas archaeological features were identified. The artefactual evidence indicated five phases of archaeological activity, with features dating from the late prehistoric, medieval, medieval/post-medieval, and post-medieval to modern wartime period. Several heavily truncated isolated prehistoric features were identified, as were field boundary ditches of medieval to the post-medieval date. Many undated, but presumed modern, postholes were found across the site. The postholes may have been the result of an extensive network of Second World War temporary timber structures known as tactical obstacles (including barbed wire entanglements and tank proof obstacles) erected during anti-invasion defence works. These structures were likely to have been part of the important Stop Line Defence network, Line A of the GHQ (General Headquarters) line of defences, which were planned to slow down a ground invasion.

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