Forming simulation of a thermoplastic commingled woven textile on a double dome

This paper presents thermoforming experiments and FE simulations of a commingled glass-PP woven composite on a double dome geometry, with the aim of assessing the correspondence of predicted and experimental shear angles. Large local deformations - especially in-plane shear, i.e. relative rotation between the two yarn families – occur when draping a textile on a three dimensional part and eventually unwanted phenomena like wrinkling or tearing may occur. The macroscopic drape behaviour of a weave is generally subdivided into: 1) The high tensile resistance along the yarn directions, expressed as non-linear stress-strain curves, and 2) The shear resistance, expressed as non-linear shear force versus shear angle curves. The constitutive model is constituted of a dedicated non-orthogonal hypo-elastic shear resistance model, previously described in [1, 2], combined with truss elements that represent the high tensile resistance along the yarn directions. This model is implemented in a user subroutine of the ABAQUS explicit FE solver. The material parameters have been identified via textile biaxial tensile tests at room temperature and bias extension tests at 200°. Thermoforming experiments are performed on a rectangular blank with the warp direction along the second symmetry plane of the tool, with a preheating temperature of 200°C, a constant mold temperature of about 70°C, and a blankholder ring. It was concluded that the shear angles were fairly well predicted for this particular case study, which could be expected in view of the fact that no wrinkles had formed during the thermoforming experiment

Mixing of fermion fields of opposite parities and baryon resonances

We consider a loop mixing of two fermion fields of opposite parities whereas the parity is conserved in a Lagrangian. Such kind of mixing is specific for fermions and has no analogy in boson case. Possible applications of this effect may be related with physics of baryon resonances. The obtained matrix propagator defines a pair of unitary partial amplitudes which describe the production of resonances of spin $J$ and different parity ${1/2}^{\pm}$ or ${3/2}^{\pm}$. The use of our amplitudes for joint description of $\pi N$ partial waves $P_{13}$ and $D_{13}$ shows that the discussed effect is clearly seen in these partial waves as the specific form of interference between resonance and background. Another interesting application of this effect may be a pair of partial waves $S_{11}$ and $P_{11}$ where the picture is more complicated due to presence of several resonance states.Comment: 22 pages, 6 figures, more detailed comparison with \pi N PW

Fermion resonance in quantum field theory

We derive accurately the fermion resonance propagator by means of Dyson summation of the self-energy contribution. It turns out that the relativistic fermion resonance differs essentially from its boson analog.Comment: 8 pages, 2 figures, revtex4 class; references added, style correction

The Rarita--Schwinger field: renormalization and phenomenology

We discuss renormalization of propagator of interacting Rarita--Schwinger field. Spin-3/2 contribution after renormalization takes usual resonance form. For non-leading spin-1/2 terms we found procedure, which guarantees absence of poles in energy plane. The obtained renormalized propagator has one free parameter and is a straight generalization of the famous free propagator of Moldauer and Case. Application of this propagator for production of $\Delta^{++}(1232)$ in \pi^{+}\particle{p}\to \pi^{+}\particle{p} leads to good description of total cross-section and to reasonable agreement with results of partial wave analysis.Comment: 19 pages, 3 figures, revtex4; misprints, min editorial change

Spin half fermions with mass dimension one: theory, phenomenology, and dark matter

We provide the first details on the unexpected theoretical discovery of a spin-one-half matter field with mass dimension one. It is based upon a complete set of dual-helicity eigenspinors of the charge conjugation operator. Due to its unusual properties with respect to charge conjugation and parity, it belongs to a non-standard Wigner class. Consequently, the theory exhibits non-locality with (CPT)^2 = - I. We briefly discuss its relevance to the cosmological `horizon problem'. Because the introduced fermionic field is endowed with mass dimension one, it can carry a quartic self-interaction. Its dominant interaction with known forms of matter is via Higgs, and with gravity. This aspect leads us to contemplate the new fermion as a prime dark matter candidate. Taking this suggestion seriously we study a supernova-like explosion of a galactic-mass dark matter cloud to set limits on the mass of the new particle and present a calculation on relic abundance to constrain the relevant cross-section. The analysis favours light mass (roughly 20 MeV) and relevant cross-section of about 2 pb. Similarities and differences with the WIMP and mirror matter proposals for dark matter are enumerated. In a critique of the theory we bare a hint on non-commutative aspects of spacetime, and energy-momentum space.Comment: 78 pages [Changes: referee-suggested improvements, additional important references, and better readability