Jack R. Vinson

Bio: Jack R. Vinson is an academic researcher from University of Delaware. The author has contributed to research in topics: Shell (structure) & Sandwich-structured composite. The author has an hindex of 30, co-authored 168 publications receiving 8303 citations.

Stresses in shallow spherical shells of composite materials subjected to localized loads.

Abstract: : Methods of analysis are developed to provide the stresses (both bending and membrane) and deformations in specially orthotropic shallow and nonshallow spherical shells of revolution subjected to localized loads at the apex. An accurate shell theory is employed including effects of circular orthotropy and transverse shear deformation. The governing equations are reduced to a single, second order complex differential equation. Solutions are obrained in terms of modified Bessel functions of non-integer order and complex argument. These functions are transformed into a set of infinite series, and upon proper non- dimensionalization, these series are shown to be uniformly and very rapidly convergent. Expressions are obtained for bending, membrane and shear stresses as well as lateral and inplane deflections everywhere in the shell. Comparisons and design curves are obtained for large variations in orthotropy and matrix shear properties which cover almost all known composite materials. Various boundary conditions, degrees of shallowness, and loading conditions are also systematically explored and reported. (Author, modified-PL)

Derivation of the Governing Equations for Thin Shells

Abstract: After the brief introduction to curvilinear coordinates in Chapter 1, one can now describe the equations of elasticity in curvilinear coordinates, and systematically reduce them to the governing equations for shells in curvilinear coordinates, employing the assumptions of shells in the process.

Composite Materials and Their Use in Structures

Abstract: This book attempts to provide a basic fundamental understanding of the physical and mathematical aspects of the materials system and structures comprised of composite materials. The introduction discusses the nature and scope of composite materials, the strengthening processes used in the manufacture of alloys, and the needs for composite materials. Then various types of fiber-reinforced materials are examined, first by discussing the properties of the component phases. Next, the behavior of dispersion-strengthened and directionally solidified eutectics is considered. An introduction to plate and shell theory is given for isotropic materials, and then the stress--strain relations thus developed are extended to deal with anisotropic materials. The deformation of a fibrous composite is analyzed for plate- and shell-type structures. The strength and fracture of composite materials are discussed in the final chapter. The book is not an encyclopedia of all previous research and solutions. 136 figures, 19 tables, 492 references. (RWR)

A method for weight optimization of flat truss-core sandwich panels under lateral loads

Abstract: : A method is presented for optimizing, on a weight basis, flat truss-core sandwich panels under lateral loads. To solve this type of problem by equating the stress level for all failure modes requires a knowledge of the stress distribution throughout the panel for the given loading. There are no available stress analysis methods of sufficient sophistication for corrugated panels under lateral loading; hence, a large portion of this report is devoted to the development of such a method of analysis. The method is essentially a deformation method; however, a technique of using Fourier type transformations makes the solution more tractable.

Energy Methods in Composite Material Structures

Abstract: Many composite material structures not only involve anisotropy, multilayer considerations and transverse shear deformation, but also have hygrothermal effects, which can be very important. True, for preliminary design one needs the simplified, easier to use analyses that have been presented earlier, but for the final design, transverse shear deformation and hygrothermal effects must be included. These thermal and moisture effects have been described in Chapter 2. Analytically they cause considerable difficulty, because with their inclusion few boundary conditions are homogeneous, hence separation of variables, used throughout the plate and shell solutions to this point, cannot be utilized straightforwardly. Only through the laborious process of transformation of variables can the procedure used herein be used [1]. Therefore, energy principles are much more convenient for use in design and analyses of plate and shell structures when hygrothermal effects are present.

Cellulose nanomaterials review: structure, properties and nanocomposites

Abstract: This critical review provides a processing-structure-property perspective on recent advances in cellulose nanoparticles and composites produced from them. It summarizes cellulose nanoparticles in terms of particle morphology, crystal structure, and properties. Also described are the self-assembly and rheological properties of cellulose nanoparticle suspensions. The methodology of composite processing and resulting properties are fully covered, with an emphasis on neat and high fraction cellulose composites. Additionally, advances in predictive modeling from molecular dynamic simulations of crystalline cellulose to the continuum modeling of composites made with such particles are reviewed (392 references).

Use of piezoelectric actuators as elements of intelligent structures

Abstract: This work presents the analytic and experimental development of piezoelectric actuators as elements of intelligent structures, i.e., structures with highly distributed actuators, sensors, and processing networks. Static and dynamic analytic models are derived for segmented piezoelectric actuators that are either bonded to an elastic substructure or embedded in a laminated composite. These models lead to the ability to predict, a priori, the response of the structural member to a command voltage applied to the piezoelectric and give guidance as to the optimal location for actuator placement. A scaling analysis is performed to demonstrate that the effectiveness of piezoelectric actuators is independent of the size of the structure and to evaluate various piezoelectric materials based on their effectiveness in transmitting strain to the substructure. Three test specimens of cantilevered beams were constructed: an aluminum beam with surface-bonded actuators, a glass/epoxy beam with embedded actuators, and a graphite/epoxy beam with embedded actuators. The actuators were used to excite steady-state resonant vibrations in the cantilevered beams. The response of the specimens compared well with those predicted by the analytic models. Static tensile tests performed on glass/epoxy laminates indicated that the embedded actuator reduced the ultimate strength of the laminate by 20%, while not significantly affecting the global elastic modulus of the specimen.

Review: current international research into cellulose nanofibres and nanocomposites

Abstract: This paper provides an overview of recent progress made in the area of cellulose nanofibre-based nanocomposites. An introduction into the methods used to isolate cellulose nanofibres (nanowhiskers, nanofibrils) is given, with details of their structure. Following this, the article is split into sections dealing with processing and characterisation of cellulose nanocomposites and new developments in the area, with particular emphasis on applications. The types of cellulose nanofibres covered are those extracted from plants by acid hydrolysis (nanowhiskers), mechanical treatment and those that occur naturally (tunicate nanowhiskers) or under culturing conditions (bacterial cellulose nanofibrils). Research highlighted in the article are the use of cellulose nanowhiskers for shape memory nanocomposites, analysis of the interfacial properties of cellulose nanowhisker and nanofibril-based composites using Raman spectroscopy, switchable interfaces that mimic sea cucumbers, polymerisation from the surface of cellulose nanowhiskers by atom transfer radical polymerisation and ring opening polymerisation, and methods to analyse the dispersion of nanowhiskers. The applications and new advances covered in this review are the use of cellulose nanofibres to reinforce adhesives, to make optically transparent paper for electronic displays, to create DNA-hybrid materials, to generate hierarchical composites and for use in foams, aerogels and starch nanocomposites and the use of all-cellulose nanocomposites for enhanced coupling between matrix and fibre. A comprehensive coverage of the literature is given and some suggestions on where the field is likely to advance in the future are discussed.

Numerical experiments in revisited brittle fracture

Abstract: The numerical implementation of the model of brittle fracture developed in Francfort and Marigo (1998. J. Mech. Phys. Solids 46 (8), 1319–1342) is presented. Various computational methods based on variational approximations of the original functional are proposed. They are tested on several antiplanar and planar examples that are beyond the reach of the classical computational tools of fracture mechanics.