Search results for "Dynamic load"
showing 10 items of 24 documents
A Strain Sensing Structural Health Monitoring System for Delaminated Composite Structures
2012
Structural Health Monitoring (SHM) for composite materials is becoming a primary task due to their extended use in safety critical applications. Different methods, based on the use of piezoelectric transducers as well as of fiber optics, has been successfully proposed to detect and monitor damage in composite structural components with particular attention focused on delamination cracks.In the present paper a Structural Health Monitoring model, based on the use of piezoelectric sensors, already proposed by the authors for isotropic damaged components, is extended to delaminated composite structures. The dynamic behavior of the host damaged structure and the bonded piezoelectric sensors is m…
Dynamic shakedown of structures with variable appended masses and subjected to repeated excitations
1996
Elastic shakedown for discrete, or finite-element discretized, structures subjected to combinations of static and time-variable loads is addressed in the hypothesis of elastic-perfectly plastic material behavior. The static load is conceived as the weight of an additional mass appended to the structure, whereas the time-variable load is conceived as an unknown sequence of excitations belonging to a specified domain, with intervals between subsequent excitations during which the structure is considered as being motionless. It is shown that, in the plane of the static and time-variable load parameters, the structure's dynamic shakedown domain is nonconvex and that its boundary curve generally…
A distributed dynamic load balancer and its implementation on multi-transputer systems for molecular dynamics simulation
1990
Abstract A new and efficient approach is described to the dynamic load-balancing problem which is central in concurrent computing. A transputer-based implementation is tested on a molecular dynamics simulation of spinodal phase separation.
A full body musculoskeletal model based on flexible multibody simulation approach utilised in bone strain analysis during human locomotion
2011
Load-induced strains applied to bone can stimulate its development and adaptation. In order to quantify the incident strains within the skeleton, in vivo implementation of strain gauges on the surfaces of bone is typically used. However, in vivo strain measurements require invasive methodology that is challenging and limited to certain regions of superficial bones only such as the anterior surface of the tibia. Based on our previous study [Al Nazer et al. (2008) J Biomech. 41:1036-1043], an alternative numerical approach to analyse in vivo strains based on the flexible multibody simulation approach was proposed. The purpose of this study was to extend the idea of using the flexible multibod…
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
Second-order hydrodynamic effects on the response of three semisubmersible floating offshore wind turbines
2020
Abstract Floating structures have become the most feasible solution for supporting wind turbines when offshore wind project move to deeper water. In this paper, a hydrodynamic analysis of three different semisubmersible floating offshore wind turbines is carried out including second-order hydrodynamic effects. The three examined platforms are V-shaped semisubmersible, Braceless semisubmersible and OC4-DeepCwind semisubmersible and are used to support the NREL 5 MW reference wind turbine. The main objective of the present study is to investigate and compare the hydrodynamic response of the three different semisubmersible floaters in two water depths (100 m, and 200 m) under different load co…
Lead-Lag-Shaped Interactive Force Estimation by Equivalent Output Injection of Sliding-Mode
2020
Estimation of interactive forces, which are mostly unavailable for direct measurement on the interface between a system and its environment, is an essential task in various motion control applications. This paper proposes an interactive force estimation method, based on the well-known equivalent output injection of the second-order sliding mode. The equivalent output injection is used to obtain a frequency-unshaped quantity that appears as a matched external disturbance and encompasses the interactive forces. Afterwards, a universal lead-lag shaper, depending on dynamics of the motion control system coupled with its environment, is used to extract an interactive force quantity. Once identif…
Muscle strength and muscle endurance of middle-aged women and men associated to type, duration and intensity of muscular load at work
1988
Muscle strength and muscle endurance in groups with different occupational muscular load was studied among 60 women and 69 men. The mean age of the subjects was 52.0 +/- 3.4 years. Isometric grip and trunk strength were measured on dynamometers, and dynamic muscle endurance by sit-ups. A job analysis was done with the AET method including the assessment of intensity, duration and type of muscular work of each subject. According to the job analysis, the subjects were classified into groups with low or high muscular load at work. The maximal isometric hand grip strength of women with a load classified as long duration of static or dynamic load on the hands at work was 86 and 88%, respectively…
Static and dynamic elasticity of some thermotropic liquid-crystalline copolyesters
1997
Two series of thermotropic liquid crystalline copolyesters were studied in static and dynamic tensile deformation. Static loading generally does not lead to any peculiar phenomena: the stress-strain diagrams are linear or convex, except one copolyester fibre, the stress-strain diagram of which is concave at high temperatures. On the contrary, in dynamic loading the elasticity modulus increased during deformation for all the samples investigated. So it can be assumed that formation of a more rigid and stable structure takes place due to the dynamic deformation.
Stochastic dynamics of linear elastic trusses in presence of structural uncertainties (virtual distortion approach)
2004
Structures involving uncertainties in material and/or in geometrical parameters are referred to as uncertain structures. Reliability analysis of such structures strongly depends on variation of parameters and probabilistic approach is often used to characterize structural uncertainties. In this paper dynamic analysis of linearly elastic system in presence of random parameter variations will be performed. In detail parameter fluctuations have been considered as inelastic, stress and parameter dependent superimposed strains. Analysis is then carried out via superposition principle accounting for response to external agencies and parameter dependent strains. Proposed method yields asymptotic s…