Simulation of Ductile Fracture of Multiple Flaws

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Kazuhiro Suga ◽  
Masanori Kikuchi ◽  
Shota Kawasaki
Keyword(s):  
Constitutive Equation ◽  
Ductile Fracture ◽  
Void Growth ◽  
Evaluation Method ◽  
Fracture Pattern ◽  
Experimental Results ◽  
Load Displacement ◽  
Fracture Processes

The effect of the interaction of multiple flaws on ductile fracture is studied numerically by Gurson’s constitutive equation. Based on experimental results, two parallel flaw and three parallel flaw problems are simulated. Flaw coalescence does not occur in some problems but does occur in other cases. In all cases, ductile fracture processes are obtained, and the results are compared with the experimental results. The fracture pattern and load-displacement curves agree well with the experimental results. The void growth term is found to be dominant for the coalescence of flaws. The slant flaw problem and the nonuniform length flaw problem are simulated and an evaluation method for the multiple flaws problem is discussed.

Simulation of Ductile Fracture for Multiple Flaws

2010 ◽  
Author(s):  
Masanori Kikuchi ◽  
Kazuhiro Suga ◽  
Shota Kawasaki
Keyword(s):  
Constitutive Equation ◽  
Ductile Fracture ◽  
Interaction Effect ◽  
Evaluation Method ◽  
Crack Problem ◽  
Fracture Pattern ◽  
Crack Coalescence ◽  
Multiple Cracks ◽  
Parallel Cracks ◽  
Fracture Processes

Interaction effect of multiple flaws on ductile fracture is studied numerically by using Gurson’s constitutive equation. Based on experiments, 2 parallel cracks problems and 3 parallel cracks problems are simulated. In some problems, crack coalescence does not occur, and it occurs in other cases. In all cases, ductile fracture processes are obtained, and results are compared with experimental ones. Fracture pattern and load-displacement curves agree well with experiments. It is shown that void growth term is dominant for the coalescence of cracks. Slanted crack problem and non-uniform length crack problem are simulated and evaluation method of multiple cracks problem is discussed.

Simulation of Fracture Behavior of Elastomer Modified Polypropylene Based on Elastoviscoplastic Constitutive Equation With Craze and Tensile Softening Law

2005 ◽  
Author(s):  
Hiroyuki Mae
Keyword(s):  
Constitutive Equation ◽  
Crack Propagation ◽  
Strain Rate ◽  
Fracture Behavior ◽  
Experimental Results ◽  
Experimental Result ◽  
Load Displacement ◽  
Macroscopic Crack ◽  
Tensile Softening ◽  
Good Agreement

The strong strain-rate dependence, neck propagation and craze evolution characterize the large plastic deformation and fracture behavior of polymer. In the latest study, Kobayashi, Tomii and Shizawa suggested the elastoviscoplastic constitutive equation based on craze evolution and annihilation and then applied it to the plane strain issue of polymer. In the previous study, the author applied their suggested elastoviscoplastic constitutive equation with craze effect to the three dimensional shell issue and then showed that the load displacement history was in good agreement with the experimental result including only microscopic crack such as craze. For the future industrial applications, the macroscopic crack had to be taken into account. For instance, an airbag deployment simulation needed the macroscopic crack prediction. Thus, the main objective of this study was to propose the tensile softening equation and then add it to the elastoviscoplastic constitutive equation with craze effect so that the load displacement history could be roughly simulated during the macroscopic crack propagation. The tested material in this study was the elastomer blended polypropylene used in the interior and exterior of automobiles. First, the material properties were obtained based on the tensile test results at wide range of strain rates: 10−4 – 102 (1/sec). Next, the fast compact tension test was conducted and then the tensile softening parameters were fixed. Then, the fast bending test and the dart impact test were carried out in order to obtain the load displacement history and also observe the macroscopic crack propagation at high strain rate. Finally, the fracture behavior was simulated and then compared with the experimental results. It was shown that the predictions of the constitutive equation with the proposed tensile softening equation were in good agreement with the experimental results.

Experimental Study of Ductile Fracture for Non-Aligned Multiple Flaws in a Plate

2009 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Koichi Saito ◽  
Bostjan Bezensek
Keyword(s):  
Experimental Study ◽  
Ductile Fracture ◽  
Estimation Procedure ◽  
Maximum Load ◽  
Experimental Results ◽  
Collapse Load ◽  
Plate Specimen ◽  
Fracture Tests ◽  
Almost All

The fitness-for-service code requires the characterization of non-aligned multiple flaws for the flaw evaluation, which is performed using a flaw proximity rule. Worldwide almost all codes provide own proximity rule, often with unclear technical bases of the application of proximity rule to ductile fracture. To clarify the appropriate proximity rule for non-aligned multiple flaws in fully plastic fracture, fracture tests on flat plate specimen with non-aligned multiple through wall flaws were conducted at ambient temperature. The emphasis of this study was put on the flaw alignment rule, which determines whether non-aligned flaws are treated as independent or aligned onto the same plane for the purpose of flaw evaluations. The effects of the flaw separation and flaw size on the maximum load were investigated. The experimental results were compared with the estimations of the collapse load using the alignment rules in the ASME Section XI, BS7910 and API 579-1 codes. A new estimation procedure specific to the fully plastic fracture was proposed and compared with the comparison with the experimental results.

TREATMENT OF PROXIMAL HUMERUS FRACTURES AND OUTCOME – A PROSPECTIVE STUDY

2021 ◽  
pp. 84-87
Author(s):  
S. Kishore Babu ◽  
S. Rajeswara Rao ◽  
Pamu.bala Avinash
Keyword(s):  
Closed Reduction ◽  
Evaluation Method ◽  
Proximal Humerus ◽  
Treatment Options ◽  
Method Comparison ◽  
Fracture Pattern ◽  
Proximal Humerus Fractures ◽  
Chi Square ◽  
Study Results ◽  
Humerus Fractures

BACKGROUND: Proximal humerus fractures are commonest fractures account for about 4 – 5% of the fractures.Complicated fracture pattern in proximal humerus are increasing due to increase inincidence of high velocity trauma. Because of inconsistency in fracture classication, treatment and evaluation method,comparison of these fractures are impeded. This studydetermines and compare the results of different modalities of xations in proximal humerus fractures and outcome. MATERIALS AND METHODS: This study was done from August 2018 to February 2020 in king Georgehospital,Visakhapatnam. Total 32 patients with proximal humerus fractures were operatedwith different modalities depend on fracture pattern.The results were evaluated using the Neers Shoulder Scoring System. RESULTS:The results show that most Neer's two part fracture had excellent to satisfactory results (85%). Neer's three part fracture also had 73% excellent to satisfactory results. Neer's four part fracture which went into failure. This study results were compared with other studies by using chi square test. CONCLUSION: The management modality depended on the pattern of the fracture andthequality of the bone .The patient's goals with treatment options for these displaced fractures included closed reduction and percutaneous screws xation (13% cases), closed reduction and percutaneous k- wires xation (9% cases) ,open reduction and internal xation (78 % cases).

Effect of Manganese Addition on Strength and Fracture Toughness in Mg-6Al-1Zn Alloy

2006 ◽  
Vol 306-308 ◽  
pp. 857-862 ◽  
Author(s):  
Taisuke Sasaki ◽  
Tokuteru Uesugi ◽  
Yorinobu Takigawa ◽  
Kenji Higashi
Keyword(s):  
Fracture Toughness ◽  
Magnesium Alloy ◽  
Yield Strength ◽  
Ductile Fracture ◽  
Manganese Content ◽  
Experimental Results ◽  
The Other ◽  
Excessive Amount ◽  
Void Coalescence ◽  
Other Hand

The effect of manganese on strength and fracture toughness was investigated using five kinds of Mg-6Al-1Zn alloys. From the experimental results, the yield strength increased with increasing in manganese content until manganese content reached 0.14 wt. %. On the other hand, further increase in yield strength was not observed in case larger than 0.14 % of manganese was added. In addition, fracture toughness decreases with increasing manganese content. Fracture of magnesium alloy was ductile fracture by void coalescence. Adding excessive amount of manganese caused the increase in the presence of inclusions. This kind of particle easily became the nucleus of microvoid. As a conclusion, manganese should be added so that coarse manganese-bearing particle is not formed. Thus, 0.14 wt. % of manganese should be added to Mg-6Al-1Zn alloy in order to develop the alloy with well-balanced relationship between strength and fracture toughness.

Ductile fracture processes in 7075 aluminum

1995 ◽  
Vol 26 (2) ◽  
pp. 407-415 ◽  
Author(s):  
C. P. You ◽  
A. W. Thompson ◽  
I. M. Bernstein
Keyword(s):  
Ductile Fracture ◽  
Fracture Processes
Sign in / Sign up

Export Citation Format

Share Document