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You searched for subject:(Nonlinear impact loads). Showing records 1 – 2 of 2 total matches.

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University of Western Australia

1. Abdolmaleki, Kourosh. Modelling of wave impact on offshore structures.

Degree: PhD, 2007, University of Western Australia

[Truncated abstract] The hydrodynamics of wave impact on offshore structures is not well understood. Wave impacts often involve large deformations of water free-surface. Therefore, a wave impact problem is usually combined with a free-surface problem. The complexity is expanded when the body exposed to a wave impact is allowed to move. The nonlinear interactions between a moving body and fluid is a complicated process that has been a dilemma in the engineering design of offshore and coastal structures for a long time. This thesis used experimental and numerical means to develop further understanding of the wave impact problems as well as to create a numerical tool suitable for simulation of such problems. The study included the consideration of moving boundaries in order to include the coupled interactions of the body and fluid. The thesis is organized into two experimental and numerical parts. There is a lack of benchmarking experimental data for studying fluid-structure interactions with moving boundaries. In the experimental part of this research, novel experiments were, therefore, designed and performed that were useful for validation of the numerical developments. By considering a dynamical system with only one degree of freedom, the complexity of the experiments performed was minimal. The setup included a plate that was attached to the bottom of a flume via a hinge and tethered by two springs from the top one at each side. The experiments modelled fluid-structure interactions in three subsets. The first subset studied a highly nonlinear decay test, which resembled a harsh wave impact (or slam) incident. The second subset included waves overtopping on the vertically restrained plate. In the third subset, the plate was free to oscillate and was excited by the same waves. The wave overtopping the plate resembled the physics of the green water on fixed and moving structures. An analytical solution based on linear potential theory was provided for comparison with experimental results. ... In simulation of the nonlinear decay test, the SPH results captured the frequency variation in plate oscillations, which indicated that the radiation forces (added mass and damping forces) were calculated satisfactorily. In simulation of the nonlinear waves, the waves progressed in the flume similar to the physical experiments and the total energy of the system was conserved with an error of 0.025% of the total initial energy. The wave-plate interactions were successfully modelled by SPH. The simulations included wave run-up and shipping of water for fixed and oscillating plate cases. The effects of the plate oscillations on the flow regime are also discussed in detail. The combination of experimental and numerical investigation provided further understanding of wave impact problems. The novel design of the experiments extended the study to moving boundaries in small scale. The use of SPH eliminated the difficulties of dealing with free-surface problems so that the focus of study could be placed on the impact forces on fixed and…

Subjects/Keywords: Hydrodynamics; Particle methods (Numerical analysis); Fluid-structure interaction; Offshore structures; Ocean waves; Smoothed particle hydrodynamics; Offshore structures, CFD; Green water; Wave impact; Nonlinear impact loads

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Abdolmaleki, K. (2007). Modelling of wave impact on offshore structures. (Doctoral Dissertation). University of Western Australia. Retrieved from http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=9682&local_base=GEN01-INS01

Chicago Manual of Style (16th Edition):

Abdolmaleki, Kourosh. “Modelling of wave impact on offshore structures.” 2007. Doctoral Dissertation, University of Western Australia. Accessed September 16, 2019. http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=9682&local_base=GEN01-INS01.

MLA Handbook (7th Edition):

Abdolmaleki, Kourosh. “Modelling of wave impact on offshore structures.” 2007. Web. 16 Sep 2019.

Vancouver:

Abdolmaleki K. Modelling of wave impact on offshore structures. [Internet] [Doctoral dissertation]. University of Western Australia; 2007. [cited 2019 Sep 16]. Available from: http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=9682&local_base=GEN01-INS01.

Council of Science Editors:

Abdolmaleki K. Modelling of wave impact on offshore structures. [Doctoral Dissertation]. University of Western Australia; 2007. Available from: http://repository.uwa.edu.au:80/R/?func=dbin-jump-full&object_id=9682&local_base=GEN01-INS01


University of Canterbury

2. Elliott, R.B. A simple hybrid testing approach for dynamic analysis of civil structural control devices.

Degree: Mechanical Engineering, 2009, University of Canterbury

Effective real-time testing of structural control devices relies on a hybrid test system that couples virtual structures under dynamic loading with physical sub-structures or devices in a dynamic test rig. The use of sensors and actuators in a closed-loop feedback system maintains the dynamic equilibrium of the overall system comprising the physical test article and virtual modelled structure. The virtual-real hybrid testing method thus alleviates much of the time and cost associated with full-scale testing and enables tests that would be infeasible without full-scale complete structural tests. Thus, it can reduce the uncertainty in designing such a full scale test by testing, in hybrid hardware in the loop fashion, the devices and sub-systems required to ensure the best overall full-scale experimental design. Hence, a major outcome is the savings in the cost, time and complexity of the resulting full scale experiment. To accomplish this goal, this research presents simple, cost-effective and robust hybrid test system, and outlines solutions to the major issues faced in developing any hybrid system. The overall approach is centred on the dSpaceTM real-time control system development tool. The major issues in developing a hybrid system are: minimal signal processing lag, optimised sensing resolution and bandwidth, and efficient model computation. All three affect the ability of the system to maintain dynamic equilibrium of the overall virtual-physical system, and thus provide an accurate test. The final system readily accommodates non-linearsingle and multi-degree-of-freedom models and an operating bandwidth of 1 kHz. Test results and experimental outcomes are based on studies of a linear single degree of freedom structure and a non-linear rocking wall system that includes impact loads and timing subject to random ground motions. The results clearly illustrate system simplicity, efficacy and how they can be used to illustrate the potential outcomes of full scale experiments but at simple, fast low cost level. Keywords:

Subjects/Keywords: hybrid testing; pseudo-dynamic testing; real-time control; virtual structures; structural control devices; nonlinear rocking wall; impact loads; timing; random ground motion.; Fields of Research::290000 Engineering and Technology::290500 Mechanical and Industrial Engineering::290501 Mechanical engineering

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Elliott, R. B. (2009). A simple hybrid testing approach for dynamic analysis of civil structural control devices. (Thesis). University of Canterbury. Retrieved from http://hdl.handle.net/10092/3571

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Elliott, R B. “A simple hybrid testing approach for dynamic analysis of civil structural control devices.” 2009. Thesis, University of Canterbury. Accessed September 16, 2019. http://hdl.handle.net/10092/3571.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Elliott, R B. “A simple hybrid testing approach for dynamic analysis of civil structural control devices.” 2009. Web. 16 Sep 2019.

Vancouver:

Elliott RB. A simple hybrid testing approach for dynamic analysis of civil structural control devices. [Internet] [Thesis]. University of Canterbury; 2009. [cited 2019 Sep 16]. Available from: http://hdl.handle.net/10092/3571.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Elliott RB. A simple hybrid testing approach for dynamic analysis of civil structural control devices. [Thesis]. University of Canterbury; 2009. Available from: http://hdl.handle.net/10092/3571

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.