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Fatigue modeling of composite ocean current turbine blade
Title
Fatigue modeling of composite ocean current turbine blade.
Creator
Akram, Mohammad Wasim, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
The success of harnessing energy from ocean current will require a reliable structural design of turbine blade that is used for energy extraction. In this study we are particularly focusing on the fatigue life of a 3m length ocean current turbine blade. The blade consists of sandwich construction having polymeric foam as core, and carbon/epoxy as face sheet. Repetitive loads (Fatigue) on the blade have been formulated from the randomness of the ocean current associated with turbulence and...
Show moreThe success of harnessing energy from ocean current will require a reliable structural design of turbine blade that is used for energy extraction. In this study we are particularly focusing on the fatigue life of a 3m length ocean current turbine blade. The blade consists of sandwich construction having polymeric foam as core, and carbon/epoxy as face sheet. Repetitive loads (Fatigue) on the blade have been formulated from the randomness of the ocean current associated with turbulence and also from velocity shear. These varying forces will cause a cyclic variation of bending and shear stresses subjecting to the blade to fatigue. Rainflow Counting algorithm has been used to count the number of cycles within a specific mean and amplitude that will act on the blade from random loading data. Finite Element code ANSYS has been used to develop an S-N diagram with a frequency of 1 Hz and loading ratio 0.1 Number of specific load cycles from Rainflow Counting in conjunction with S-N diagram from ANSYS has been utilized to calculate fatigue damage up to 30 years by Palmgren-Miner's linear hypothesis.
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Date Issued
2010
PURL
http://purl.flvc.org/FAU/2867332
Subject Headings
Turbines, Blades, Materials, Fatigue, Marine turbines, Mathematical models, Structural dynamics, Composite materials, Mathematical models, Sandwich construction, Fatigue
Format
Document (PDF)
Fatigue and fracture of foam cores used in sandwich composites
Title
Fatigue and fracture of foam cores used in sandwich composites.
Creator
Saenz, Elio., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
This study focused on the fracture and fatigue crack growth behavior in polyvinylchloride (PVC) and polyethersulfone (PES) foams. A new sandwich double cantilever beam (DCB) test specimen was implemented. Elastic foundation and finite element analysis and experimental testing confirmed that the DCB specimen is appropriate for static and cyclic crack propagation testing of soft polymer foams. A comprehensive experimental mechanical analysis was conducted on PVC foams of densities ranging from...
Show moreThis study focused on the fracture and fatigue crack growth behavior in polyvinylchloride (PVC) and polyethersulfone (PES) foams. A new sandwich double cantilever beam (DCB) test specimen was implemented. Elastic foundation and finite element analysis and experimental testing confirmed that the DCB specimen is appropriate for static and cyclic crack propagation testing of soft polymer foams. A comprehensive experimental mechanical analysis was conducted on PVC foams of densities ranging from 45 to 100 kg/m3 and PES foams of densities ranging from 60 to 130 kg/m3. An in-situ scanning electron microscope study on miniature foam fracture specimens showed that crack propagation in the PVC foam was inter-cellular and in the PES foam, failure occurred predominately by extensional failure of vertical cell edges. Sandwich DCB specimens were loaded cyclically as well. For the PVC foams, the crack growth rates were substantially influenced by the density. For the PES foams, there was no clear indication about the influence of foam density on the crack growth rate.
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Date Issued
2012
PURL
http://purl.flvc.org/FAU/3352829
Subject Headings
Sandwich construction, Composite materials, Fibrous composites, Strains and stresses, Management, Laminated materials, Plastics, Fatigue
Format
Document (PDF)
Study of edge effects in laminated sandwich specimens
Title
Study of edge effects in laminated sandwich specimens.
Creator
Mankuzhy, Pradeep Prabhakaran., Florida Atlantic University, Merry, Stephanie L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description
Different methods have been employed to calculate the interlaminar stresses and to study the edge effect in a laminated sandwich specimens under uniaxial tension. However, Finite Element Analysis and Force Balance Method produced stress values which disagreed in both magnitude and sign, a controversy which exists in the case of composite laminates also. Experimental methods, photoelastic coating method and strain gaging, were attempted to obtain the strain distribution on the top surface of a...
Show moreDifferent methods have been employed to calculate the interlaminar stresses and to study the edge effect in a laminated sandwich specimens under uniaxial tension. However, Finite Element Analysis and Force Balance Method produced stress values which disagreed in both magnitude and sign, a controversy which exists in the case of composite laminates also. Experimental methods, photoelastic coating method and strain gaging, were attempted to obtain the strain distribution on the top surface of a sandwich specimen in three point bending. However, these conventional methods failed to show the sharp strain gradient that exists near the free edge. The Force Balance Method was simplified for sandwich specimens by considering the face laminate as a homogeneous and orthotropic material with averaged properties. Simplified expressions were also obtained for calculating the boundary layer thickness. The boundary layer thickness was found to vary linearly with core thickness for the cases considered.
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Date Issued
1989
PURL
http://purl.flvc.org/fcla/dt/14523
Subject Headings
Sandwich construction--Fatigue, Composite materials, Strains and stresses, Structural analysis (Engineering)
Format
Document (PDF)