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Suong Van Hoa - One of the best experts on this subject based on the ideXlab platform.
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Flexural Stiffness of thick walled composite tubes
Composite Structures, 2016Co-Authors: M. I. Geuchy Ahmad, Suong Van HoaAbstract:Composite tubes have been used in many applications such as pipes, robot arms, drive shafts, electrical conduits, printing rollers, tube structures for sports equipment, rocket structures, satellite truss structures, landing gears for helicopters, and structural building members etc. For thin wall tubes made of isotropic materials, the Flexural Stiffness is usually determined by using strength of material approach with the expression EI, where E is the material modulus and I the cross section inertia. For composite tubes where many layers with different orientations are involved, the situation is more complex. Comparison of the results obtained using strength of materials equation and equation based on elasticity shows a large difference. In order to be sure of the validity of the results, experimental validation is necessary.This paper presents the experimental work done on the determination of the Flexural Stiffness of thick composite tubes. Thick composite tubes were manufactured using an automated fiber placement machine. A special test set up was developed to subject the tubes to pure bending. Both strain gages and Digital Image Correlation were used to determine the strains, and subsequently the Flexural Stiffness. Experimental Flexural Stiffnesses of the tubes were determined. Results are compared with those calculated using the different equations.
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Flexural Stiffness of Thick Walled Composite Tubes
2016Co-Authors: Suong Van Hoa, El Geuchy Ahmed, Canhui ZhangAbstract:Composite tubes have been used in many applications such as pipes, robot arms, drive shafts, electrical conduits, printing rollers, tube structures for sports equipment, rocket structures, satellite truss structures, landing gears for helicopters, and structural building members etc. For thin wall tubes made of isotropic materials, the Flexural Stiffness is usually determined by using strength of material approach with the expression EI, where E is the material modulus and I the cross section inertia. For thin walled composite tubes where many layers with different orientations are involved, one may tempt to use the same equation with E replaced by Ex to take care of the fiber orientations. However this may not be correct. Adding to this the increasing thickness of the cylinder, then the inaccuracy of the equation may be even more. By using elasticity approach, an equation for the determination of the Stiffness of thick composite cylinders was derived by previous researchers. It was shown by experimental work that the equation based on elasticity provides more accurate results that that based on strength of materials approach. This paper presents some behavior of the bending Stiffness of thick walled composite tubes.
M. I. Geuchy Ahmad - One of the best experts on this subject based on the ideXlab platform.
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Flexural Stiffness of thick walled composite tubes
Composite Structures, 2016Co-Authors: M. I. Geuchy Ahmad, Suong Van HoaAbstract:Composite tubes have been used in many applications such as pipes, robot arms, drive shafts, electrical conduits, printing rollers, tube structures for sports equipment, rocket structures, satellite truss structures, landing gears for helicopters, and structural building members etc. For thin wall tubes made of isotropic materials, the Flexural Stiffness is usually determined by using strength of material approach with the expression EI, where E is the material modulus and I the cross section inertia. For composite tubes where many layers with different orientations are involved, the situation is more complex. Comparison of the results obtained using strength of materials equation and equation based on elasticity shows a large difference. In order to be sure of the validity of the results, experimental validation is necessary.This paper presents the experimental work done on the determination of the Flexural Stiffness of thick composite tubes. Thick composite tubes were manufactured using an automated fiber placement machine. A special test set up was developed to subject the tubes to pure bending. Both strain gages and Digital Image Correlation were used to determine the strains, and subsequently the Flexural Stiffness. Experimental Flexural Stiffnesses of the tubes were determined. Results are compared with those calculated using the different equations.
Matthew J Mchenry - One of the best experts on this subject based on the ideXlab platform.
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The Flexural Stiffness of superficial neuromasts in the zebrafish (Danio rerio) lateral line.
Journal of Experimental Biology, 2007Co-Authors: Matthew J Mchenry, Sietse M. Van NettenAbstract:SUMMARY Superficial neuromasts are structures that detect water flow on the surface of the body of fish and amphibians. As a component of the lateral line system, these receptors are distributed along the body, where they sense flow patterns that mediate a wide variety of behaviors. Their ability to detect flow is governed by their structural properties, yet the micromechanics of superficial neuromasts are not well understood. The aim of this study was to examine these mechanics in zebrafish ( Danio rerio ) larvae by measuring the Flexural Stiffness of individual neuromasts. Each neuromast possesses a gelatinous cupula that is anchored to hair cells by kinocilia. Using quasi-static bending tests of the proximal region of the cupula, we found that Flexural Stiffness is proportional to the number of hair cells, and consequently the number of kinocilia, within a neuromast. From this relationship, the Flexural Stiffness of an individual kinocilium was found to be 2.4×10 –20 N m 2 . Using this value, we estimate that the 11 kinocilia in an average cupula generate more than four-fifths of the total Flexural Stiffness in the proximal region. The relatively minor contribution of the cupular matrix may be attributed to its highly compliant material composition (Young9s modulus of ∼21 Pa). The distal tip of the cupula is entirely composed of this material and is consequently predicted to be at least an order of magnitude more flexible than the proximal region. These findings suggest that the transduction of flow by a superficial neuromast depends on structural dynamics that are dominated by the number and height of kinocilia.
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The Flexural Stiffness of superficial neuromasts in the zebrafish (Danio rerio) lateral line.
The Journal of experimental biology, 2007Co-Authors: Matthew J Mchenry, Sietse M. Van NettenAbstract:Superficial neuromasts are structures that detect water flow on the surface of the body of fish and amphibians. As a component of the lateral line system, these receptors are distributed along the body, where they sense flow patterns that mediate a wide variety of behaviors. Their ability to detect flow is governed by their structural properties, yet the micromechanics of superficial neuromasts are not well understood. The aim of this study was to examine these mechanics in zebrafish (Danio rerio) larvae by measuring the Flexural Stiffness of individual neuromasts. Each neuromast possesses a gelatinous cupula that is anchored to hair cells by kinocilia. Using quasi-static bending tests of the proximal region of the cupula, we found that Flexural Stiffness is proportional to the number of hair cells, and consequently the number of kinocilia, within a neuromast. From this relationship, the Flexural Stiffness of an individual kinocilium was found to be 2.4 x 10(-20) N m2. Using this value, we estimate that the 11 kinocilia in an average cupula generate more than four-fifths of the total Flexural Stiffness in the proximal region. The relatively minor contribution of the cupular matrix may be attributed to its highly compliant material composition (Young's modulus of approximately 21 Pa). The distal tip of the cupula is entirely composed of this material and is consequently predicted to be at least an order of magnitude more flexible than the proximal region. These findings suggest that the transduction of flow by a superficial neuromast depends on structural dynamics that are dominated by the number and height of kinocilia.
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functions of fish skin Flexural Stiffness and steady swimming of longnose gar lepisosteus osseus
The Journal of Experimental Biology, 1996Co-Authors: John H Long, Melina E Hale, Matthew J Mchenry, Mark W. WestneatAbstract:The functions of fish skin during swimming remain enigmatic. Does skin stiffen the body and alter the propagation of the axial undulatory wave? To address this question, we measured the skin9s in situ Flexural Stiffness and in vivo mechanical role in the longnose gar Lepisosteus osseus. To measure Flexural Stiffness, dead gar were gripped and bent in a device that measured applied bending moment (N m) and the resulting midline curvature (m-1). From these values, the Flexural Stiffness of the body (EI in N m2) was calculated before and after sequential alterations of skin structure. Cutting of the dermis between two caudal scale rows significantly reduced the Flexural Stiffness of the body and increased the neutral zone of curvature, a region of bending without detectable Stiffness. Neither bending property was significantly altered by the removal of a caudal scale row. These alterations in skin structure were also made in live gar and the kinematics of steady swimming was measured before and after each treatment. Cutting of the dermis between two caudal scale rows, performed under anesthesia, changed the swimming kinematics of the fish: tailbeat frequency (Hz) and propulsive wave speed (body lengths per second, L s-1) decreased, while the depth (in L) of the trailing edge of the tail increased. The decreases in tailbeat frequency and wave speed are consistent with predictions of the theory of forced, harmonic vibrations; wave speed, if equated with resonance frequency, is proportional to the square root of a structure9s Stiffness. While it did not significantly reduce the body9s Flexural Stiffness, surgical removal of a caudal scale row resulted in increased tailbeat amplitude and the relative total hydrodynamic power. In an attempt to understand the specific function of the scale row, we propose a model in which a scale row resists medio-lateral force applied by a single myomere, thus functioning to enhance mechanical advantage for bending. Finally, surgical removal of a precaudal scale row did not significantly alter any of the kinematic variables. This lack of effect is associated with a lower midline curvature of the precaudal region during swimming compared with that of the caudal region. Overall, these results demonstrate a causal relationship between skin, the passive Flexural Stiffness it imparts to the body and the influence of body Stiffness on the undulatory wave speed and cycle frequency at which gar choose to swim.
Thomas L Daniel - One of the best experts on this subject based on the ideXlab platform.
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Flexural Stiffness in Insect Wings: Effects of Wing Venation and Stiffness Distribution on Passive Bending
American Entomologist, 2005Co-Authors: Stacey A Combes, Thomas L DanielAbstract:American Entomologist • Spring 2005 During flight, insect wings bend and twist dramatically, and the instantaneous, threedimensional shape of wings may influence many aspects of flight performance. Insects have little control over this bending and twisting—wing deformations are largely passive and are controlled primarily by the architecture and material properties of the wing. However, our understanding of how insect wing design affects flexibility and passive wing deformation remains limited. Here, we discuss how insect wing venation affects overall bending Stiffness, how Stiffness varies throughout wings, and how these features of wing design affect passive bending. The pattern of supporting veins in insect wings varies widely among insect orders and families. Given the large phylogenetic changes in wing venation pattern (Fig. 1), one might expect insect wings to display large mechanical differences that would affect their deformability during flight. We examined the relationship between insect wing flexibility and venation by measuring Flexural Stiffness (EI) and quantifying venation pattern in 16 insect species from six orders. Flexural Stiffness is a composite measure of the overall bending Stiffness of a wing, combining the material properties of the wing (E, Young’s modulus) and the geometric distribution of this material (I, second moment of area). We measured overall EI of wings in the spanwise direction (from base to tip) and the chordwise direction (from leading to trailing edge) by performing static bending tests. We attached each wing at the base (or leading edge), applied a known force at the tip (or trailing edge), and measured the displacement of the wing. We then calculated EI with a simple beam equation (see Combes and Daniel 2003a). We also digitized the wing venation of each species and derived five measures of venation pattern (Combes and Daniel 2003a). To remove the effects of phylogeny, we calculated standardized independent contrasts of venation and Stiffness measurements and examined the correlations between these contrasts. Our measurements show that EI is strongly correlated with wing size (Fig. 2), but the details of venation pattern do not appear to affect overall Flexural Stiffness (no significant correlations were found between contrasts of wing venation pattern and EI). The measurements also reveal a large anisotropy, or difference, between spanwise and chordwise Flexural Stiffness; spanwise EI is ≈1 to 2 orders of magnitude greater than chordwise EI in all species tested (Fig. 2). To determine how wing structure may contribute to this pattern of Stiffness anisotropy, we created a simplified finite-element model of a Manduca (hawkmoth) wing. To create this model, a digitized Flexural Stiffness in Insect Wings: Effects of Wing Venation and Stiffness Distribution on Passive Bending
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Flexural Stiffness in insect wings ii spatial distribution and dynamic wing bending
The Journal of Experimental Biology, 2003Co-Authors: Stacey A Combes, Thomas L DanielAbstract:SUMMARY The dynamic, three-dimensional shape of flapping insect wings may influence many aspects of flight performance. Insect wing deformations during flight are largely passive, and are controlled primarily by the architecture and material properties of the wing. Although many details of wing structure are well understood, the distribution of Flexural Stiffness in insect wings and its effects on wing bending are unknown. In this study, we developed a method of estimating spatial variation in Flexural Stiffness in both the spanwise and chordwise direction of insect wings. We measured displacement along the wing in response to a point force, and modeled Flexural Stiffness variation as a simple mathematical function capable of approximating this measured displacement. We used this method to estimate Flexural Stiffness variation in the hawkmoth Manduca sexta , and the dragonfly Aeshna multicolor . In both species, Flexural Stiffness declines sharply from the wing base to the tip, and from the leading edge to the trailing edge; this variation can be approximated by an exponential decline. The wings of M. sexta also display dorsal/ventral asymmetry in Flexural Stiffness and significant differences between males and females. Finite element models based on M. sexta forewings demonstrate that the measured spatial variation in Flexural Stiffness preserves rigidity in proximal regions of the wing, while transferring bending to the edges, where aerodynamic force production is most sensitive to subtle changes in shape.
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Flexural Stiffness in insect wings. I. Scaling and the influence of wing venation.
Journal of Experimental Biology, 2003Co-Authors: Stacey A Combes, Thomas L DanielAbstract:During flight, many insect wings undergo dramatic deformations that are controlled largely by the architecture of the wing. The pattern of supporting veins in wings varies widely among insect orders and families, but the functional significance of phylogenetic trends in wing venation remains unknown, and measurements of the mechanical properties of wings are rare. In this study, we address the relationship between venation pattern and wing flexibility by measuring the Flexural Stiffness of wings (in both the spanwise and chordwise directions) and quantifying wing venation in 16 insect species from six orders. These measurements show that spanwise Flexural Stiffness scales strongly with the cube of wing span, whereas chordwise Flexural Stiffness scales with the square of chord length. Wing size accounts for over 95% of the variability in measured Flexural Stiffness; the residuals of this relationship are small and uncorrelated with standardized independent contrasts of wing venation characters. In all species tested, spanwise Flexural Stiffness is 1-2 orders of magnitude larger than chordwise Flexural Stiffness. A finite element model of an insect wing demonstrates that leading edge veins are crucial in generating this spanwise-chordwise anisotropy.
Stacey A Combes - One of the best experts on this subject based on the ideXlab platform.
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Flexural Stiffness in Insect Wings: Effects of Wing Venation and Stiffness Distribution on Passive Bending
American Entomologist, 2005Co-Authors: Stacey A Combes, Thomas L DanielAbstract:American Entomologist • Spring 2005 During flight, insect wings bend and twist dramatically, and the instantaneous, threedimensional shape of wings may influence many aspects of flight performance. Insects have little control over this bending and twisting—wing deformations are largely passive and are controlled primarily by the architecture and material properties of the wing. However, our understanding of how insect wing design affects flexibility and passive wing deformation remains limited. Here, we discuss how insect wing venation affects overall bending Stiffness, how Stiffness varies throughout wings, and how these features of wing design affect passive bending. The pattern of supporting veins in insect wings varies widely among insect orders and families. Given the large phylogenetic changes in wing venation pattern (Fig. 1), one might expect insect wings to display large mechanical differences that would affect their deformability during flight. We examined the relationship between insect wing flexibility and venation by measuring Flexural Stiffness (EI) and quantifying venation pattern in 16 insect species from six orders. Flexural Stiffness is a composite measure of the overall bending Stiffness of a wing, combining the material properties of the wing (E, Young’s modulus) and the geometric distribution of this material (I, second moment of area). We measured overall EI of wings in the spanwise direction (from base to tip) and the chordwise direction (from leading to trailing edge) by performing static bending tests. We attached each wing at the base (or leading edge), applied a known force at the tip (or trailing edge), and measured the displacement of the wing. We then calculated EI with a simple beam equation (see Combes and Daniel 2003a). We also digitized the wing venation of each species and derived five measures of venation pattern (Combes and Daniel 2003a). To remove the effects of phylogeny, we calculated standardized independent contrasts of venation and Stiffness measurements and examined the correlations between these contrasts. Our measurements show that EI is strongly correlated with wing size (Fig. 2), but the details of venation pattern do not appear to affect overall Flexural Stiffness (no significant correlations were found between contrasts of wing venation pattern and EI). The measurements also reveal a large anisotropy, or difference, between spanwise and chordwise Flexural Stiffness; spanwise EI is ≈1 to 2 orders of magnitude greater than chordwise EI in all species tested (Fig. 2). To determine how wing structure may contribute to this pattern of Stiffness anisotropy, we created a simplified finite-element model of a Manduca (hawkmoth) wing. To create this model, a digitized Flexural Stiffness in Insect Wings: Effects of Wing Venation and Stiffness Distribution on Passive Bending
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Flexural Stiffness in insect wings ii spatial distribution and dynamic wing bending
The Journal of Experimental Biology, 2003Co-Authors: Stacey A Combes, Thomas L DanielAbstract:SUMMARY The dynamic, three-dimensional shape of flapping insect wings may influence many aspects of flight performance. Insect wing deformations during flight are largely passive, and are controlled primarily by the architecture and material properties of the wing. Although many details of wing structure are well understood, the distribution of Flexural Stiffness in insect wings and its effects on wing bending are unknown. In this study, we developed a method of estimating spatial variation in Flexural Stiffness in both the spanwise and chordwise direction of insect wings. We measured displacement along the wing in response to a point force, and modeled Flexural Stiffness variation as a simple mathematical function capable of approximating this measured displacement. We used this method to estimate Flexural Stiffness variation in the hawkmoth Manduca sexta , and the dragonfly Aeshna multicolor . In both species, Flexural Stiffness declines sharply from the wing base to the tip, and from the leading edge to the trailing edge; this variation can be approximated by an exponential decline. The wings of M. sexta also display dorsal/ventral asymmetry in Flexural Stiffness and significant differences between males and females. Finite element models based on M. sexta forewings demonstrate that the measured spatial variation in Flexural Stiffness preserves rigidity in proximal regions of the wing, while transferring bending to the edges, where aerodynamic force production is most sensitive to subtle changes in shape.
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Flexural Stiffness in insect wings. I. Scaling and the influence of wing venation.
Journal of Experimental Biology, 2003Co-Authors: Stacey A Combes, Thomas L DanielAbstract:During flight, many insect wings undergo dramatic deformations that are controlled largely by the architecture of the wing. The pattern of supporting veins in wings varies widely among insect orders and families, but the functional significance of phylogenetic trends in wing venation remains unknown, and measurements of the mechanical properties of wings are rare. In this study, we address the relationship between venation pattern and wing flexibility by measuring the Flexural Stiffness of wings (in both the spanwise and chordwise directions) and quantifying wing venation in 16 insect species from six orders. These measurements show that spanwise Flexural Stiffness scales strongly with the cube of wing span, whereas chordwise Flexural Stiffness scales with the square of chord length. Wing size accounts for over 95% of the variability in measured Flexural Stiffness; the residuals of this relationship are small and uncorrelated with standardized independent contrasts of wing venation characters. In all species tested, spanwise Flexural Stiffness is 1-2 orders of magnitude larger than chordwise Flexural Stiffness. A finite element model of an insect wing demonstrates that leading edge veins are crucial in generating this spanwise-chordwise anisotropy.