Using the Taguchi Method and Finite Element Method to Analyze a Robust New Design for Titanium Alloy Prick Hole Extrusion

AbstractIn the process of prick hole extrusion, many factors must be controlled to obtain the required plastic strain and desired tolerance values. The major factors include lubricant, extrusion speed, billet temperature, and die angle. In this paper, we employed rigid-plastic finite element (FE) DEFORMTM software, to investigate the plastic deformation behavior of a titanium alloy (Ti-6Al-4V) billet as it was extruded through a conical prick hole die. We systematically examined the influence of the semi-cone angle on the prick hole die, the diameter of prick hole die, the factor of friction, the velocity of the ram and the temperature of the billet, under various extrusion conditions. We analyzed the strain, stress and damage factor distribution in the extrusion process. We used the Taguchi method to determine optimum design parameters, and our results confirmed the suitability of the proposed design, which enabled a prick hole die to achieve perfect extrusion during finite element testing

Associated Z0H0Z^0H^0 production with leptonic decays at LHC in next-to-leading order QCD

In this work we investigate the effects of the littlest Higgs model (LHM) up to the QCD next-to-leading order (NLO) on the $Z^0H^0$ associated production at the CERN Large Hadron Collider (LHC). We study the dependences of the leading order and NLO QCD corrected integrated cross sections for this process on the factorization/renormalization scale and the LHM parameters. We also provide the distributions of the transverse momenta of final decay products $\mu^-$ and $\tau^-$. Our results show that the heavy neutral gauge bosons $Z_H$ and $A_H$ could induce significant discrepancies from the standard model predictions. It is found that when the LHM parameters are taken as $c=0.5$, $c^{\prime}=0.22$, $f=4 TeV$ and $\mu=(M_H+M_Z)/2$, the effects at the $\sqrt{s}=14 TeV$ LHC from the heavy neutral gauge boson are about 12.83% and 10.37% to the leading order and NLO QCD corrected integrated cross sections, respectively. We also conclude that the NLO QCD corrections at the $\sqrt{s}=14 TeV$ LHC can obviously reduce the scale uncertainty of the integrated cross section, and significantly enhance the differential cross sections of $p_T^{\mu^-}$ and $p_T^{\tau^-}$. It demonstrates that the precision measurement of the $Z^0H^0$ associated production process at the LHC could provide the clue of the LHM physics.Comment: 26 pages, 11 figure

Revisiting the large extra dimension effects on WW-pair production at the LHC in NLO QCD

In the framework of the large extra dimensions (LED) model, we investigate the effects induced by the Kaluza-Klein (KK) gravitons up to the QCD next-to-leading order (NLO) on the $W$-pair production followed by a subsequential $W$-decay at the CERN LHC. We depict the regions in the $\mathcal{L}-M_{S}$ parameter space where the LED effect can and cannot be observed from the analyses of the $pp \to W^+W^- + X$ and $pp \to W^+W^- \to W^{\pm}l^{\mp}\stackrel{(-)}{\nu} + X$ processes. We find that the ability of probing the LED effects can be improved by taking the cutoffs for the invariant mass of $W$-pair and the transverse momentum of the final lepton. Our results demonstrate that the NLO QCD corrections to observables are significant, and do not show any improvement for the renormalization/factorization scale uncertainty on the QCD NLO corrected cross section, because the LO result underestimates the scale dependence.Comment: 25 pages, 14 figure