3,694 research outputs found
An experimental procedure for the Iosipescu composite specimen tested in the modified Wyoming fixture
A detailed description is given of the experimental procedure for testing composite Iosipescu specimens in the modified Wyoming fixture. Specimen preparation and strain gage instrumentation are addressed. Interpretation of the experimental results is discussed. With the proper experimental procedure and setup, consistent and repeatable shear properties are obtained
A comparison of three popular test methods for determining the shear modulus of composite materials
Three popular shear tests (the 10 degree off-axis, the plus or minus 45 degree tensile, and the Iosipescu specimen tested in the modified Wyoming fixture) for shear modulus measurement are evaluated for a graphite-epoxy composite material system. A comparison of the shear stress-strain response for each test method is made using conventional strain gage instrumentation and moire interferometry. The uniformity and purity of the strain fields in the test sections of the specimens are discussed, and the shear responses obtained from each test technique are presented and compared. For accurate measurement of shear modulus, the 90 degree Iosipescu specimen is recommended
Zero-norm states and stringy symmetries
We identify spacetime symmetry charges of 26D open bosonic string theory from
an infinite number of zero-norm states (ZNS) with arbitrary high spin in the
old covariant first quantized string spectrum. We give various evidences to
support this identification. These include massive sigma-model calculation,
Witten string field theory calculation, 2D string theory calculation and, most
importantly, three methods of high-energy stringy scattering amplitude
calculations. The last calculations explicitly prove Gross's conjectures in
1988 on high energy symmetry of string theory.Comment: 6 pages. Talks presented by Jen-Chi Lee at XXVIII Spanish Relativity
Meeting (ERE2005),"A Century of Relativity Physics",Oviedo,Spain,6-10 Sep
2005 and "4th Meeting on constrained Dynamics and Quantum Gravity",Cala
Gonone,Sardinia,Italy,12-16 Sep 2005. To appear in the Journal of Physics:
Conference Serie
UV-finite scalar field theory with unitarity
In this paper we show how to define the UV completion of a scalar field
theory such that it is both UV-finite and perturbatively unitary. In the UV
completed theory, the propagator is an infinite sum of ordinary propagators. To
eliminate the UV divergences, we choose the coefficients and masses in the
propagator to satisfy certain algebraic relations, and define the infinite sums
involved in Feynman diagram calculation by analytic continuation. Unitarity can
be proved relatively easily by Cutkosky's rules. The theory is equivalent to
infinitely many particles with specific masses and interactions. We take the
theory as an example and demonstrate our idea through explicit Feynman
diagram computation.Comment: 14 pages, references adde
Composite material shear property measurement using the Iosipescu specimen
A detailed evaluation of the suitability of the Iosipescu specimen tested in the modified Wyoming fixture is presented. Finite element analysis and moire interferometry are used to assess the uniformity of the shear stress field in the test section of unidirectional and cross-ply graphite-epoxy composites. The nonuniformity of the strain field and the sensitivity of some fiber orientations to the specimen/fixture contact mechanics are discussed. The shear responses obtained for unidirectional and cross-ply graphite-epoxy composites are discussed and problems associated with anomalous behavior are addressed. An experimental determination of the shear response of a range of material systems using strain gage instrumentation and moire interferometry is performed
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