Models of nonlinear kinematic hardening based on different versions of rate-independent maxwell fluid

Different models of finite strain plasticity with a nonlinear kinematic hardening are analyzed in a systematic way. All the models are based on a certain formulation of a rate-independent Maxwell fluid, which is used to render the evolution of backstresses. The properties of each material model are determined by the underlying formulation of the Maxwell fluid. The analyzed approaches include the multiplicative hyperelastoplasticity, additive hypoelasto-plasticity and the use of generalized strain measures. The models are compared with respect to different classification criteria, such as the objectivity, thermodynamic consistency, pure volumetric-isochoric split, shear stress oscillation, exact integrability, and w-invariance

Extended concept of representative directions to describe inelastic behaviour of electrospun polymers

The concept of representative directions allows one to generalize onedimensional uniaxial material models to more general constitutive equations, suitable for arbitrary multi-axial loading scenarios. The procedure preserves the thermodynamic consistency and the resulting material model satisfies the principle of objectivity. In the current paper, the concept is modified by the introduction of new kinematics. Some features of the resulting constitutive equations as well as the applicability of the extended concept to real materials are discussed. For demonstration purposes, the plastic behaviour of an electrospun polymer is modelled under large strain non-monotonic loading

On exploiting the weak invariance of multiplicative elasto-plasticity for efficient numerical integration

The paper is devoted to the efficient and robust implementation of a certain finite-strain plasticity model, formulated with in the popular multiplicative framework. The model was proposed by Shutov and Kreißig (2008), and it captures the nonlinear behavior of metallic materials, including the combine disotropic/kinematic hardening and viscosity. A new implicit time stepping procedure is suggested here, which can be used for the stress computation at each Gauß point of the finite element discretization. The model of Shutov and Kreißig exhibits the so-called weak invariance of the solution under arbitrary isochoric change of the reference configuration. The presented algorithm benefits from this special structure of the constitutive equations: The weak invariance property is exploited for construction of the numerical integration procedure; the resulting procedure preserves the weak invariance. The inelastic incompressibility is exactly preserved as well to suppress the error accumulation; the algorithm is unconditionally stable and first-orderaccurate. In terms of accuracy, the proposed algorithm is comparable with the Euler Backward Method (EBM), but it is superior to EMB with respect to efficiency and robustness

Real-time Monitoring for the Next Core-Collapse Supernova in JUNO

Core-collapse supernova (CCSN) is one of the most energetic astrophysical events in the Universe. The early and prompt detection of neutrinos before (pre-SN) and during the SN burst is a unique opportunity to realize the multi-messenger observation of the CCSN events. In this work, we describe the monitoring concept and present the sensitivity of the system to the pre-SN and SN neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO), which is a 20 kton liquid scintillator detector under construction in South China. The real-time monitoring system is designed with both the prompt monitors on the electronic board and online monitors at the data acquisition stage, in order to ensure both the alert speed and alert coverage of progenitor stars. By assuming a false alert rate of 1 per year, this monitoring system can be sensitive to the pre-SN neutrinos up to the distance of about 1.6 (0.9) kpc and SN neutrinos up to about 370 (360) kpc for a progenitor mass of 30$M_{\odot}$ for the case of normal (inverted) mass ordering. The pointing ability of the CCSN is evaluated by using the accumulated event anisotropy of the inverse beta decay interactions from pre-SN or SN neutrinos, which, along with the early alert, can play important roles for the followup multi-messenger observations of the next Galactic or nearby extragalactic CCSN.Comment: 24 pages, 9 figure

Potential of Core-Collapse Supernova Neutrino Detection at JUNO

JUNO is an underground neutrino observatory under construction in Jiangmen, China. It uses 20kton liquid scintillator as target, which enables it to detect supernova burst neutrinos of a large statistics for the next galactic core-collapse supernova (CCSN) and also pre-supernova neutrinos from the nearby CCSN progenitors. All flavors of supernova burst neutrinos can be detected by JUNO via several interaction channels, including inverse beta decay, elastic scattering on electron and proton, interactions on C12 nuclei, etc. This retains the possibility for JUNO to reconstruct the energy spectra of supernova burst neutrinos of all flavors. The real time monitoring systems based on FPGA and DAQ are under development in JUNO, which allow prompt alert and trigger-less data acquisition of CCSN events. The alert performances of both monitoring systems have been thoroughly studied using simulations. Moreover, once a CCSN is tagged, the system can give fast characterizations, such as directionality and light curve

Detection of the Diffuse Supernova Neutrino Background with JUNO

As an underground multi-purpose neutrino detector with 20 kton liquid scintillator, Jiangmen Underground Neutrino Observatory (JUNO) is competitive with and complementary to the water-Cherenkov detectors on the search for the diffuse supernova neutrino background (DSNB). Typical supernova models predict 2-4 events per year within the optimal observation window in the JUNO detector. The dominant background is from the neutral-current (NC) interaction of atmospheric neutrinos with 12C nuclei, which surpasses the DSNB by more than one order of magnitude. We evaluated the systematic uncertainty of NC background from the spread of a variety of data-driven models and further developed a method to determine NC background within 15\% with {\it{in}} {\it{situ}} measurements after ten years of running. Besides, the NC-like backgrounds can be effectively suppressed by the intrinsic pulse-shape discrimination (PSD) capabilities of liquid scintillators. In this talk, I will present in detail the improvements on NC background uncertainty evaluation, PSD discriminator development, and finally, the potential of DSNB sensitivity in JUNO

Models of nonlinear kinematic hardening based on different versions of rate-independent maxwell fluid

Different models of finite strain plasticity with a nonlinear kinematic hardening are analyzed in a systematic way. All the models are based on a certain formulation of a rate-independent Maxwell fluid, which is used to render the evolution of backstresses. The properties of each material model are determined by the underlying formulation of the Maxwell fluid. The analyzed approaches include the multiplicative hyperelastoplasticity, additive hypoelasto-plasticity and the use of generalized strain measures. The models are compared with respect to different classification criteria, such as the objectivity, thermodynamic consistency, pure volumetric-isochoric split, shear stress oscillation, exact integrability, and w-invariance

On exploiting the weak invariance of multiplicative elasto-plasticity for efficient numerical integration

ABSTRACT The talk is devoted to the efficient and robust numerical integration of constitutive equations governing finite strain elasto-plasticity. We utilize in a consistent manner the approach based on numerous multiplicative decompositions of the deformation gradient. The nonlinear kinematic hardening is incorporated basing on the approach of Lion [1], the nonlinear distortional hardening is introduced through its generalization presented in The key notion of the talk is the property of so-called weak invariance of constitutive relations under isochoric change of the reference configuration The resulting algorithms are first order accurate and unconditionally stable. Moreover, they exactly preserve the restriction of inelastic incompressibility which supresses the error accumulation. Numerical tests are used to compare the new algorithms with some known modifications of the classical Euler backward method

Extended concept of representative directions to describe inelastic behaviour of electrospun polymers

The concept of representative directions allows one to generalize onedimensional uniaxial material models to more general constitutive equations, suitable for arbitrary multi-axial loading scenarios. The procedure preserves the thermodynamic consistency and the resulting material model satisfies the principle of objectivity. In the current paper, the concept is modified by the introduction of new kinematics. Some features of the resulting constitutive equations as well as the applicability of the extended concept to real materials are discussed. For demonstration purposes, the plastic behaviour of an electrospun polymer is modelled under large strain non-monotonic loading