Search results for "Dynamic load"
showing 10 items of 24 documents
In-vitro fatigue and fracture performance of three different ferrulized implant connections used in fixed prosthesis
2021
Background/purpose: The aim of the present in vitro study was to evaluate fatigue resistance of dental fixtures in three different types of fixture/abutment finishing line. Materials and methods: Transmucosal dental implants, with or without ferrulized neck, underwent fatigue tests (static and dynamic load) using the following standard protocol: UNI EN ISO 14801:2016. Two types of loading devices (screw- or cement-retained restoration) were also tested, and fatigue cycle tests were run to failure. Data of static and dynamic load tests were analyzed by proper statistical methods. Results: Following standard protocol for fatigue testing, the ILC type (Implant Level with ferrulized neck and ce…
Optimal design of steel frames accounting for buckling
2013
A formulation of a special design problem devoted to elastic perfectly plastic steel frame structures subjected to different combinations of static and dynamic loads is presented. In particular, a minimum volume design problem formulation is presented and the structure is designed to be able to elastically behave for the assigned fixed loads, to elastically shakedown in presence of serviceability load conditions and to prevent the instantaneous collapse for suitably chosen combinations of fixed and ultimate seismic loadings as well as of fixed and wind actions. The actions that the structure must suffer are evaluated by making reference to the actual Italian seismic code. The dynamic respon…
Multicriterion design of frames with constraints on buckling
2011
The present paper is devoted to the optimal design of frame structures subjected to static and dynamic loading assuming the material behaviour as elastic perfectly plastic. The relevant optimal design problem is formulated as a minimum volume search problem. The minimum volume structure is determined under suitable constraints on the design variables as well as accounting for different resistance limits: the elastic shakedown limit and the instantaneous collapse limit, considering for each limit condition suitably chosen amplified load combinations. The effects of the dynamic actions are studied on the grounds of the dynamic features of the structure taking into account the structural perio…
Semiactive control for floating offshore wind turbines subject to aero-hydro dynamic loads
2011
Wind and wave dynamic loads might cause undesirable vibrations that affect the structure integrity and system performance of floating offshore wind turbines. This paper addresses the problem of dynamic load mitigation by using semiactive control techniques with the tuned liquid column dampers placed on the turbine’s tower. The control law is formulated based on the mixed H2/H∞ methods for ensuring the system stability and reliability. Furthermore, the proposed controller only uses output feedback so as to avoid the dependence on the knowledge of the states of the system. Peer Reviewed
Optimal Design of Trusses According to a Plastic Shakedown Criterion
2004
The optimal design of elastic-perfectly plastic truss structures subjected to quasi-statically loads variable within a given load domain is studied. The actions are given as the combination of fixed load and perfect cyclic load. Suitably chosen load multipliers are given. A minimum volume formulation of the design problem with assigned limit load multiplier is developed and it is provided on the grounds of a statical approach as well as of a kinematical approach. The incremental collapse (ratchetting) of the optimal structure is prevented, as long as the loads are not greater than some prescribed values, by special constraints suitably introduced in the search problem. The Kuhn-Tucker equat…
A bilateral convergent bounding technique for plastic deformations
1990
For the class of elastic perfectly plastic discrete structures, subjected to a dynamic loading history, a bilateral bounding technique for plastic deformations has been studied. The computation of the bound is founded on the concept that to obtain it, any history of fictitious plastic deformations can be used, if only admissible. Such history is obtained by solving a sequence of linear programming problems (LPPs) with a multiple step compared to the step of the sequence of the quadratic programming problems (QPPs) adopting in the classic elasto-plastic analysis. The constraints of the LPPs coincide with the constraints of the QPPs, while the objective function is a linear combination of var…
Non-stationary spectral moments of base excited MDOF systems
1988
The paper deals with the evaluation of non-stationary spectral moments of multi-degree-of-freedom (MDOF) line systems subjected to seismic excitations. The spectral moments of the response are evaluated in incremental form solution by means of an unconditionally stable step-by-step procedure. As an application, the statistics of the largest peak of the response are also evaluated.
Discrete variable design of frames subjected to seismic actions accounting for element slenderness
2015
An optimal design problem formulation of elastic plastic frames under different combinations of fixed and seismic loads is presented. The optimal structure must behave elastically for the fixed loads, shakedown for serviceability conditions and prevent instantaneous collapse for fixed and high seismic loads. P-Delta effects and element buckling are considered. An appropriate modal technique is utilized. The design variables can have components in a continuous field or, alternatively, in chosen discrete sets or, yet, both kind of variables can be present. The design problem is formulated on the ground of a statical approach. The applications are related to steel frames.
Concurrent molecular dynamics simulation of spinodal phase transition on transputer arrays
1990
Abstract We describe a concurrent implementation on cost-effective transputer arrays of a molecular dynamics program to efficiently simulate physical systems consisting of thousands of mobile particles with an interaction range much shorter than the system dimensions. This program, which uses a geometric decomposition strategy and includes a distributed dynamic load balancer, has been extensively tested by simulating the two-dimensional spinodal phase separation of a large Lennard-Jones system.
Shakedown design of structures under dynamic loading
2010
The optimal (minimum volume) design of elastic plastic structures under static and dynamic loads is studied. The minimum volume design is reached accounting for different resistance limits: it is required that the optimal structure simultaneously satisfies the elastic shakedown limit and the instantaneous collapse limit, or alternatively the elastic and the plastic shakedown limits, adopting for each limit condition a suitably chosen load combination and some appropriate load amplifiers. The load combinations are characterized by the presence of fixed loads, quasi-statical cyclic loads and dynamic (seismic) loads. Reference is made to the Italian Code related to structural analysis and desi…