Elastic Stiffness of Three-Dimensional Braided Textile Structural Composites

2008 ◽  
pp. 404-404-18 ◽  
Author(s):  
C-L Ma ◽  
J-M Yang ◽  
T-W Chou
Keyword(s):  
Three Dimensional ◽  
Elastic Stiffness ◽  
Structural Composites

Effect of Adhesive Behavior on Normal Stress Distributions in the Single-Lap Adhesive Joints

2015 ◽  
Vol 1088 ◽  
pp. 769-773
Author(s):  
Xiao Cong He
Keyword(s):  
Finite Element ◽  
Normal Stress ◽  
Three Dimensional ◽  
Adhesive Layer ◽  
Elastic Stiffness ◽  
Adhesive Joints ◽  
Stress Distributions ◽  
Element Analysis ◽  
Element Technique ◽  
Three Dimensional Finite Element

The effect of adhesives behavior on the normal stress distributions of single-lap adhesive joints is investigated using the three-dimensional finite element technique. Numerical examples are provided to show the influence on the normal stresses of the joints using adhesives of different characteristics which encompass the entire spectrum of elastic stiffness behaviour. finite element analysis solutions of the normal stress distributions in the adhesive layer have been obtained for four typical characteristics of adhesives. The results indicate that Young’s modulus and Poisson’s ratios of adhesives strongly affect the normal stress distributions of the joints.

scholarly journals Influence of three-dimensional nanoparticle branching on the Young’s modulus of nanocomposites: Effect of interface orientation

2015 ◽  
Vol 112 (21) ◽  
pp. 6533-6538 ◽  
Author(s):  
Shilpa N. Raja ◽  
Andrew C. K. Olson ◽  
Aditya Limaye ◽  
Kari Thorkelsson ◽  
Andrew Luong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Three Dimensional ◽  
Elastic Stiffness ◽  
Limited Attention ◽  
Unexpected Finding ◽  
Covalent Bonds ◽  
Lattice Spring Model ◽  
Common Block

With the availability of nanoparticles with controlled size and shape, there has been renewed interest in the mechanical properties of polymer/nanoparticle blends. Despite the large number of theoretical studies, the effect of branching for nanofillers tens of nanometers in size on the elastic stiffness of these composite materials has received limited attention. Here, we examine the Young's modulus of nanocomposites based on a common block copolymer (BCP) blended with linear nanorods and nanoscale tetrapod Quantum Dots (tQDs), in electrospun fibers and thin films. We use a phenomenological lattice spring model (LSM) as a guide in understanding the changes in the Young's modulus of such composites as a function of filler shape. Reasonable agreement is achieved between the LSM and the experimental results for both nanoparticle shapes—with only a few key physical assumptions in both films and fibers—providing insight into the design of new nanocomposites and assisting in the development of a qualitative mechanistic understanding of their properties. The tQDs impart the greatest improvements, enhancing the Young's modulus by a factor of 2.5 at 20 wt.%. This is 1.5 times higher than identical composites containing nanorods. An unexpected finding from the simulations is that both the orientation of the nanoscale filler and the orientation of X-type covalent bonds at the nanoparticle-ligand interface are important for optimizing the mechanical properties of the nanocomposites. The tQD provides an orientational optimization of the interfacial and filler bonds arising from its three-dimensional branched shape unseen before in nanocomposites with inorganic nanofillers.

On the Optimal Design of Bodies With Material Symmetries

1994 ◽  
Author(s):  
Giannantonio Sacchi Landriani ◽  
Alberto Taliercio
Keyword(s):  
Optimal Design ◽  
Fiber Orientation ◽  
Extreme Values ◽  
Three Dimensional ◽  
Necessary Optimality Conditions ◽  
Transversely Isotropic ◽  
Elastic Stiffness ◽  
The Body ◽  
Simultaneous Optimization ◽  
Material Symmetry

Abstract These notes are concerned with the optimal design of two dimensional, in-plane loaded structural elements and three dimensional bodies, made of aleotropic materials, with regard to both the elastic and the ultimate behaviour. Sec. 2 is devoted to finding the local orientations of the material symmetry axes in 3D orthotropic solids, corresponding to extreme values of the global elastic stiffness. These orientations are shown to be such that collinearity of principal stress and principal strains is achieved throughout the body. In the particular case of transversely isotropic or cubic materials, optimal orientations are shown to depend both on a material parameter and the strain field. A certain orientation of the material symmetry axes may correspond either to a minimum or to a maximum in the elastic stiffness, depending on whether the material has ‘high’ or ‘low shear modulus’. These results are then specialized to plane orthotropic bodies, in which case the theoretical findings obtained by other authors are recovered. In the plane case, also simultaneous optimization of fiber orientation and density is dealt with. Sec. 3 concerns optimal limit design of plastic 2D in-plane loaded orthotropic structures. Fiber orientation and density are assumed as design variables. Here again, necessary optimality conditions are analytically found and their mechanical interpretation is studied. Analogies with both the numerical results of other authors and the elastic case are observed and discussed as well.

Quantification of Diastolic Viscoelastic Properties of Isolated Cardiac Muscle Cells

2001 ◽  
Author(s):  
Catalin F. Baicu ◽  
Michael R. Zile
Keyword(s):  
Cardiac Muscle ◽  
Viscoelastic Properties ◽  
Three Dimensional ◽  
Pressure Overload ◽  
Muscle Cells ◽  
Elastic Stiffness ◽  
Experimental Conditions ◽  
Cardiac Muscle Cells ◽  
Diastolic Properties

Abstract Pathological processes which cause diastolic congestive heart failure (CHF), such as pressure overload hypertrophy (POH), produce abnormalities in the material properties of cardiac muscle cells (cardiomyocytes) and may selectively alter its elastic stiffness, viscosity, or both. Previous methods used to characterize these cardiomyocyte viscoelastic properties were constrained by specific biological and engineering limitations, which prevented testing in conditions that mimic normal physiology. The current study proposes an uniaxial variable-rate stretching method, in which isolated cardiomyocytes embedded in a three-dimensional gel matrix were subjected to stretch. Physiological Ca++ (2.5 mM) and rapid stretch rates up to 100 μm/sec provided experimental conditions parallel to in vivo physiology. The proposed method identified and individually quantified both cellular stiffness and viscosity, and showed that POH increased both elastic and viscous cardiomyocyte diastolic properties.

First-Principles Study on Elastic Properties of AlN

2013 ◽  
Vol 821-822 ◽  
pp. 841-844 ◽  
Author(s):  
Xin Tan ◽  
Zhen Yang Xin ◽  
Xue Jie Liu ◽  
Qing Ge Mu
Keyword(s):  
Elastic Properties ◽  
Brittle Material ◽  
First Principles ◽  
Elastic Anisotropy ◽  
Three Dimensional ◽  
Elastic Stiffness ◽  
Wurtzite Structure ◽  
Shear Moduli ◽  
Young’S Moduli ◽  
Zinc Blende

Structural and elastic properties of AlN are investigated by using First-principles. Both of wurtzite and zinc-blende structures are investigated, respectively. The bulk moduli of the wurtzite structure and zinc blende AlN are 194.2GPa and 187GPa, which obtained by the elastic stiffness constants respectively. Shear moduli are 136GPa and 124GPa. Young's moduli are 331GPa and 305GPa. Poisson's ratio and Pugh criterion suggests that both of them are brittle material. The brittleness of wurtzite AlN is higher than that of zinc-blende AlN. The elastic anisotropy of the bulk moduli and shear moduli were discussed. Three-dimensional anisotropic of the young's modulus were analyzed.

Equivalent Elastic Constants of Truss Core Sandwich Plates

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Hong-Xia Wang ◽  
Samuel W. Chung
Keyword(s):  
Elastic Constants ◽  
A Priori ◽  
Three Dimensional ◽  
Closed Form Solution ◽  
Elastic Stiffness ◽  
Form Solution ◽  
Laminated Plates ◽  
Element Analysis ◽  
Truss Core ◽  
Anisotropic Elastic

A plate structure of a triangular truss core sandwiched by two panels is treated as an equivalent homogeneous laminated plate by obtaining equivalent anisotropic elastic constants. The equivalent elastic constants are obtained by considering generalized Hook’s law of a three dimensional elastic body with no a priori assumption and the equilibrium of a segment deformed by bending moments. To verify the accuracy of the equivalent elastic constants, a linear static analysis of sandwiched aluminum plates subjected to lateral pressure is carried out. The results of the finite element analysis applied to the equivalent laminated plates are compared with those of a NASTRAN analysis of the original structural layouts. The results are also compared with a closed-form solution, which simplifies the sandwiched plate as a homogeneous orthotropic thick plate continuum (Lok and Cheng, 2000, “Elastic Stiffness Properties and Behavior of Truss-Core Sandwich Panel,” J. Struct. Eng., 126(5), pp. 552–559). As the maximum deflections of three analyses agreed closely, one has assurance that the method of the homogeneous plate with equivalent elastic constants is valid and useful.

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