Fracture criteria of ductile metals under nonmonotonic loading

1985 ◽  
Vol 17 (3) ◽  
pp. 299-304
Author(s):  
V. M. Segal
Keyword(s):  
Fracture Criteria ◽  
Ductile Metals

Shear Constraint and Macroscopic Fracture Criteria for Ductile Metals

1975 ◽  
Vol 42 (1) ◽  
pp. 15-24 ◽  
Author(s):  
M. A. Kaplan ◽  
G. A. Rowell
Keyword(s):  
Internal Pressure ◽  
Shear Fracture ◽  
Maximum Shear Stress ◽  
Fracture Initiation ◽  
Tensile Tests ◽  
Initiation Site ◽  
The Body ◽  
Fracture Criteria ◽  
Ductile Metals ◽  
Stress States

The role of material constraint in the shear fracture of ductile metals is investigated by means of a series of torsion and internal pressure tests on aluminum alloy tubing combined with analytical descriptions of the stress states at fracture. These descriptions include work hardening and, in the case of a tube under internal pressure, account for the nonaxisymmetric deformations that always precede fracture. The results, which indicate that shear fracture initiation depends on conditions at points far removed from the initiation site when the maximum shear stress vector there is directed through the interior of the body, are supported by the results of tensile tests on plates with shallow notches. These latter experiments are also used to show that tensile and shear fracture are governed by independent fracture criteria. A continuum fracture theory for ductile metals, based on the concepts of material constraint and independent fracture criteria, is proposed. The theory predicts fracture in terms of the stress state. A critical analysis of the theory is provided along with examples of fracture phenomena which the theory predicts, but which are not explained by existing theories.

scholarly journals Progressive failure of ductile metals: Description via a three-dimensional coupled CZM–XFEM based approach

2021 ◽  
Vol 243 ◽  
pp. 107498
Author(s):  
Konstantinos Nikolakopoulos ◽  
Jean-Philippe Crété ◽  
Patrice Longère
Keyword(s):  
Progressive Failure ◽  
Three Dimensional ◽  
Ductile Metals

The influence of infill density gradient on the mechanical properties of PLA optimized structures by additive manufacturing

2021 ◽  
pp. 146442072110071
Author(s):  
AIL Pais ◽  
C Silva ◽  
MC Marques ◽  
JL Alves ◽  
J Belinha
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Additive Manufacturing ◽  
Structural Optimization ◽  
Meshless Method ◽  
Load Case ◽  
Fused Filament Fabrication ◽  
Ductile Metals ◽  
Four Point Bending ◽  
Bending Load

The aim of this work is the development of a novel framework for structural optimization using bio-inspired remodelling algorithm adapted to additive manufacturing. The fact that polylactic acid (PLA, E = 3145 MPa (Young’s modulus) according to the supplier for parts obtained by injection) shows a similar parameterized behavior with ductile metals, in the sense that both materials are characterized by a bi-linear elastic-plastic law, allows to simulate and prototype parts to be further constructed in ductile metals at a lower cost and then be produced with more expensive fabrication processes. Moreover, cellular materials allow for a significant weight reduction and therefore reduction of production costs. Structural optimization algorithms based on biological phenomena were used to determine the density distribution of the infill density of the specimens. Several simple structures were submitted to distinct complex load cases and analyzed using the mentioned optimization algorithms combined with the finite element method and a meshless method. The surface was divided according to similar density and then converted to stereolitography files and infilled with the gyroid structure at the desired density determined before, using open-source slicing software. Smoothing functions were used to smooth the density field obtained with the remodeling algorithms. The samples were printed with fused filament fabrication technology and submitted to mechanical flexural tests similar to the ones analyzed analytically, namely three- and four-point bending tests. Thus, the factors of analysis were the smoothing parameter and the remodeling method, and the responses evaluated were stiffness, specific stiffness, maximum force, and mass. The experimental results correlated (obtaining accuracy of 35% for the three-point bending load case and 5% for the four-point bending load case) to the numerical results in terms of flexural stiffness and it was found that the complexity of the load case is relevant for the efficiency of the functional gradient. The fused filament fabrication process is still not accurate enough to be able to experimentally compare the results based of finite element method and meshless method analyses.

Mechanical Properties of Swelling Clays

1988 ◽  
Vol 127 ◽  
Author(s):  
D. Broc ◽  
F. Plas ◽  
J. C. Robinet
Keyword(s):  
Mechanical Properties ◽  
Mechanical Stability ◽  
Radioactive Waste Disposal ◽  
Storage Facility ◽  
Practical Application ◽  
Fracture Criteria ◽  
Waste Package ◽  
Swelling Clays ◽  
Clay Barrier ◽  
Macroscopic Examination

ABSTRACTThe safety of vitrified radioactive waste disposal in granite is based on the concept of multiple barriers, which include an engineered clay barrier placed between the waste package and the granite. The mechanical properties of the swelling clays used were studied with a view to practical application for storage facility dimensioning. This involved a macroscopic examination of the clays swelling capacities (for sealing of storage boreholes) and fracture criteria (mechanical stability).

Mechanical Properties of Nanocrystalline Materials Produced by In Situ Consolidation Ball Milling

2008 ◽  
Vol 579 ◽  
pp. 15-28 ◽  
Author(s):  
Carl C. Koch ◽  
Khaled M. Youssef ◽  
Ron O. Scattergood
Keyword(s):  
Mechanical Properties ◽  
Ball Milling ◽  
Nanocrystalline Materials ◽  
Preparation Method ◽  
High Strength ◽  
Al Alloys ◽  
Ductile Metals ◽  
Cu Alloys ◽  
Bulk Nanocrystalline

This paper reviews a method, “in situ consolidation ball milling” that provides artifactfree bulk nanocrystalline samples for several ductile metals such as Zn, Al and Al alloys, and Cu and Cu alloys. The preparation method is described in this paper and examples of the mechanical behavior of nanocrystalline materials made by this technique are given. It is found that in such artifact-free metals, combinations of both high strength and good ductility are possible.

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