Search results for "Tearing"
showing 6 items of 6 documents
Prediction of Ductile Fractures Occurrence in Deep Drawing of Square Boxes
1996
Abstract The authors propose a new approach for the prediction of tearing in the deep drawing process of square boxes. Such an approach is based on a damage mechanics formulation and in particular on the yield condition for damaging materials proposed by Tvergaard and Needleman and on a strain controlled nucleation model. The flow rule associated to the yield condition is introduced in a finite element explicit formulation founded on the solution of the dynamic equilibrium equation and on an explicit time integration scheme. By this way the developed model allows to calculate the void volume fraction value during the deep drawing process of square boxes and consequently to predict the insur…
Optimal Blankholder Force Path in Sheet Metal Forming Processes: An Al Based Procedure
1999
Abstract Blankholder force plays a fundamental role in the deep drawing process mechanics since it controls, by friction, the material flow into the die cavity. The availability of computer controlled hydraulic presses in the industries promoted a new research field focused on the definition of optimal BHF histories, function of the punch displacement; such studies were aimed to the determination of the so called “process window”, i.e. the BHF path which permits to obtain the maximum height sound component avoiding both wrinkling and tearing. In the paper a design procedure is proposed in order to determine the optimal BHF path in an axisymmetric deep drawing process: in particular, a close…
Fracture behavior and mechanical, thermal, and rheological properties of biodegradable films extruded by flat die and calender
2020
The development of biodegradable materials for tailored applications, particularly in the field of polymeric films and sheets, is a challenging technological goal as well as a contribution to help protect the environment. Poly(lactic) acid (PLA) is a promising substitute for several oil-based polymers; however, to overcome its thermal and mechanical drawbacks, researchers have developed solutions such as blending PLA with polybutylene adipate terephthalate (PBAT), which is capable of increasing the ductility of the final material. In this study, PLA/PBAT binary blends, with minimum possible content of nonrenewable materials, were examined from processing, thermal, morphological, and rheolog…
High-order methods for the simulation of hydromagnetic instabilities in core-collapse supernovae
2011
AbstractWe present an assessment of the accuracy of a recently developed MHD code used to study hydromagnetic flows in supernovae and related events. The code, based on the constrained transport formulation, incorporates unprecedented ultra-high-order methods (up to 9th order) for the reconstruction and the most accurate approximate Riemann solvers. We estimate the numerical resistivity of these schemes in tearing instability simulations.
Temporal evolution of neoclassical tearing modes in the frequently interrupted regime
2010
A phenomenological method for description of temporal evolution of neoclassical tearing modes in the frequently interrupted regime (FIR) is proposed. The method makes it possible to predict the beginning and the end of the FIR regime as well as the frequency of the FIR drops. A few experimental parameters which are used in the model are commonly measured quantities. Several specific ASDEX Upgrade (http://en.wikipedia.org/wiki/ASDEX_Upgrade) FIR discharges with different heating and different FIR behavior are analyzed in detail.
Magmatism Along Lateral Slab Edges: Insights From the Diamante-Enotrio-Ovidio Volcanic-Intrusive Complex (Southern Tyrrhenian Sea)
2019
Volcanic‐intrusive complexes often formed along lateral slab edges as a consequence of subduction‐induced mantle flow. We investigate this process in the southern Tyrrhenian Sea by integrating multibeam bathymetry, seismic‐reflection data, regional magnetic anomalies data, and seismological data. The interpretation of the data highlights the presence of magmatic intrusions that locally reach the seafloor forming volcanic edifices. Chimneys, lava flows, and laccoliths are observed beneath and surrounding the volcanoes. The emplacement and cooling of the magma occurred during the Brunhes Chron. The volcanoes are not active even if the hydrothermal activity occurs. The volcanic‐intrusive compl…