39,854 research outputs found
Effects of the roller feed ratio on wrinkling failure in conventional spinning of a cylindrical cup
In this study, wrinkling failure in conventional spinning of a cylindrical cup has been investigated by using both finite element (FE) analysis and experimental methods. FE simulation models of a spinning experiment have been developed using the explicit finite element solution method provided by the software Abaqus. The severity of wrinkles is quantified by calculating the standard deviation of the radial coordinates of element nodes on the edge of the workpiece obtained from the FE models. The results show that the severity of wrinkles tends to increase when increasing the roller feed ratio. A forming limit study for wrinkling has been carried out and shows that there is a feed ratio limit beyond which the wrinkling failure will take place. Provided that the feed ratio is kept below this limit, the wrinkling failure can be prevented. It is believed that high compressive tangential stresses in the local forming zone are the causes of the wrinkling failure. Furthermore, the computational performance of the solid and shell elements in simulating the spinning process are examined and the tool forces obtained from wrinkling and wrinkle-free models are compared. Finally, the effects of the feed ratio on variations of the wall thickness of the spun cylindrical cup are investigated. </jats:p
Is U3Ni3Sn4 best described as near a quantum critical point?
Although most known non-Fermi liquid (NFL) materials are structurally or
chemically disordered, the role of this disorder remains unclear. In
particular, very few systems have been discovered that may be stoichiometric
and well ordered. To test whether U3Ni3Sn4 belongs in this latter class, we
present measurements of the x-ray absorption fine structure (XAFS) of
polycrystalline and single-crystal U3Ni3Sn4 samples that are consistent with no
measurable local structural disorder. We also present temperature-dependent
specific heat data in applied magnetic fields as high as 8 T that show features
that are inconsistent with the antiferromagnetic Griffiths' phase model, but do
support the conclusion that a Fermi liquid/NFL crossover temperature increases
with applied field. These results are inconsistent with theoretical
explanations that require strong disorder effects, but do support the view that
U3Ni3Sn4 is a stoichiometric, ordered material that exhibits NFL behavior, and
is best described as being near an antiferromagnetic quantum critical point.Comment: 9 pages, 8 figures, in press with PR
Higgs revised in Supersymmetric Economical 3-3-1 model with B/\mu-type terms
We re-investigate the scalar potential and the Higgs sector of the
supersymmetric economical 3-3-1 model (SUSYE331) in the presence of the B/\mu
type terms which has many important consequences. First, the model contains no
massless Higgs fields. Second, we prove that the soft mass parameters of
Higgses must be at the SU(3)_L scale. As a result, the masses of the Higgses
drift toward this scale except one light real neutral Higgs with the mass of
m_Z|cos(2\gamma)| at the tree level. We also show that there are some Higgses
containing many properties of the Higgses in the minimal supersymmetric
standard model (MSSM), especially in the neutral Higgs sector. One exact
relation in the MSSM, m^2_H^{+/-}=m^2_A+m^2_W, is still true in the SUSYE331.
Based on this result we make some comments on the lepton flavor violating
decays of these Higgses as one of signatures of new physics in the SUSYE331
model which may be detected by present colliders.Comment: Matches version accepted for publication in EPJC. Typos are
corrected. We add a new section, a new appendix, a new figure and new
references to explain more clearly the properties of the lightest neutral
Higgs. Results unchange
- …