Optimization of Forging Dies by Means of Simulation

2000 ◽  
Author(s):  
Nikolai Biba ◽  
Alexey Vlasov ◽  
Andrey Lishny ◽  
Sergei Stebounov
Keyword(s):  
Tool Life ◽  
Low Cycle Fatigue ◽  
Die Design ◽  
The Other ◽  
Cycle Fatigue ◽  
Critical Areas ◽  
Element Simulation ◽  
Closed Die Forging ◽  
Cost Simulation ◽  
Die Deflection

Abstract Due to relatively high cost of the tooling in closed die forging the increasing of tool life is vitally important. The dies can failure due to cracks caused by overloading, low cycle fatigue or abrasive wear. On the other hand, the die deflection can cause deterioration of the forged part shape. The paper presents the ways for increasing of tool life and product accuracy by means of implementation of simulation. It can be done by modification of die design that reduces stress concentration in fillets or by using assembly dies that have splits in critical areas in combination with shrink rings and inserts. Finite element simulation allows to analyze the effectiveness of different variants of die design and to select the most effective ones in terms of tooling cost. Simulation also generates profiled shape of the die that compensates elastic deformation of tooling set and provides precise geometrical accuracy of a forged part.

Short Crack Initiation during Low-Cycle Fatigue in SAF 2507 Duplex Stainless Steel

2007 ◽  
Vol 345-346 ◽  
pp. 343-346 ◽  
Author(s):  
M.C. Marinelli ◽  
Suzanne Degallaix ◽  
I. Alvarez-Armas
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Room Temperature ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Surface Strain ◽  
The Other ◽  
Cycle Fatigue ◽  
Cyclic Tests ◽  
Characteristic Microstructure

In this work, the formation of fatigue cracks is considered as a nucleation process due to the development of a characteristic microstructure formed just beneath the specimen surface. Strain controlled cyclic tests were carried out at room temperature at total strain ranges εt = 0.8 and 1.2% in flat specimens of SAF 2507 Duplex Stainless Steel (DSS). The results show that for this DSS, at εt = 0.8%, the correlation between phases (Kurdjumov-Sacks crystallographic relation) plays an important role in the formation of microcracks. On the other hand, at εt = 1.2%, microcracks initiate in the ferritic phase and the K-S relation does not seem to affect the formation of the cracks.

LOW CYCLE FATIGUE BEHAVIOR OF Zn-22Al ALLOY IN SUPERPLASTIC REGION AND NON-SUPERPLASTIC REGION

2008 ◽  
Vol 22 (31n32) ◽  
pp. 5477-5482 ◽  
Author(s):  
ATSUMICHI KUSHIBE ◽  
TSUTOMU TANAKA ◽  
YORINOBU TAKIGAWA ◽  
KENJI HIGASHI
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Crack Tip ◽  
The Other ◽  
Al Alloy ◽  
Cycle Fatigue ◽  
Secondary Cracks

The crack propagation properties for ultrafine-grained Zn -22 wt % Al alloy during low cycle fatigue (LCF) in the superplastic region and the non-superplastic region were investigated and compared with the corresponding results for several other materials. With the Zn - 22 wt % Al alloy, it was possible to conduct LCF tests even at high strain amplitudes of more than ±5%, and the alloy appeared to exhibit a longer LCF lifetime than the other materials examined. The fatigue life is higher in the superplastic region than in the non-superplastic region. The rate of fatigue crack propagation in the superplastic region is lower than that in the other materials in the high J-integral range. In addition, the formation of cavities and crack branching were observed around a crack tip in the supereplastic region. We therefore conclude that the formation of cavities and secondary cracks as a result of the relaxation of stress concentration around the crack tip results in a reduction in the rate of fatigue crack propagation and results in a longer fatigue lifetime.

scholarly journals Finite Element Simulation of Multi-Axial Low Cycle Fatigue of Material SA333

2014 ◽  
Vol 86 ◽  
pp. 158-165
Author(s):  
J. De ◽  
S. Bhattacharjee ◽  
S. Dhar ◽  
S.K. Acharyya ◽  
S.K. Gupta ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Element Simulation

scholarly journals On design of fatigue resistance metallic parts

2020 ◽  
Vol 70 (2) ◽  
pp. 17-21
Author(s):  
Strain Posavljak
Keyword(s):  
Fatigue Life ◽  
Fatigue Resistance ◽  
Low Cycle Fatigue ◽  
The Other ◽  
Design Solution ◽  
Cycle Fatigue ◽  
Large Drop ◽  
Good Design ◽  
Life Data ◽  
Metallic Parts

This paper is devoted to design of metallic parts exposed to low cycle fatigue. Two flat discs, as representatives of these parts, were discussed. The first with 8, and the second with 64 eccentrically arranged holes. Their resistance to low cycle fatigue was investigated. Cyclic properties of two aerospace steels nominated for workmanship, plus planned revolves per minute and revolves per minute of 5% above planned, are taken into account. On the base of estimated low cycle fatigue life data, good design solution was discovered. On the other hand, it was shown that the both mentioned discs would have a large drop of resistance to low cycle fatigue for revolves per minute of 5% above planned.

Long and Short Radius Elbow Experiments and Evaluation of Advanced Constitutive Models to Simulate the Responses

2015 ◽  
Author(s):  
Nazrul Islam ◽  
Matthew Fenton ◽  
Tasnim Hassan
Keyword(s):  
Finite Element ◽  
Low Cycle Fatigue ◽  
Kinematic Hardening ◽  
Constitutive Models ◽  
Image Correlation ◽  
Cycle Fatigue ◽  
Element Simulation ◽  
Piping Systems ◽  
Diameter Change ◽  
Dic Technique

Low-cycle fatigue (LCF) and strain ratcheting responses of long and short radius elbows are studied experimentally and analytically. Elbow piping components are widely used in piping systems, however, the prediction of their low-cycle fatigue and ratcheting responses remain a challenge. Hence, a systematic set of short and long radius elbow LCF responses are developed by prescribing displacement-controlled loading cycles with or without internal pressure. A setup comprised of four LVDTs was utilized to measure diameter change during cyclic loading. In order to evaluate the accuracy of the strain gage data, strains are also acquired using the digital image correlation (DIC) technique. Recorded fatigue responses are analyzed in understanding the differences in LCF lives between the long and short radius elbows. The Chaboche nonlinear kinematic hardening constitutive model in ANSYS and a modified version of this model are evaluated for their simulation capability against the recorded elbow responses. The experimental and finite element simulation responses are presented in this article.

scholarly journals Расчет общей предельной прочности корпуса газовоза

2021 ◽  
Vol 46 (1) ◽  
Author(s):  
Keyword(s):  
Ultimate Strength ◽  
Maximum Stress ◽  
Conflicts Of Interest ◽  
Low Cycle Fatigue ◽  
Bending Moment ◽  
The Other ◽  
Cycle Fatigue ◽  
Advantages And Disadvantages ◽  
Minimum Probability ◽  
Arctic Navigation

На примере газовоза с ледовым классом Arc-7 проводится сравнение метода расчета предельной прочности отношения моментов и метода малоцикловой усталости. Делаются выводы о преимуществах и недостатках каждого метода. Работа сопровождается подробными расчетами предельной прочности по методу отношения моментов и малоцикловой усталости с числовыми значениями. Данное исследование может быть интересно специалистам, работающим в области расчетов прочности. Ключевые слова: предельная прочность, волновой момент, накопление повреждений, малоцикловая усталость This work covers the comparison of two methods of calculating the ultimate strength: one using the ratio of moments, and the other one using the low-cycle fatigue of a maximum stress range and minimum probability of exceedance – with the example of gas carriers operating in Arctic navigation areas. Detailed conclusions on the advantages the advantages and disadvantages of each method are made. The work is accompanied by detailed calculations and numerical values; may be of interest to specialists working in the strength calculations field. Keywords: ultimate strength, hull bending moment, fatigue damge, low-cycle fatigue Contribution of the authors: the authors contributed equally to this article. The authors declare no conflicts of interest

Finite element simulation technique for evaluation of opening stresses under high plasticity

2021 ◽  
pp. 1-21
Author(s):  
Ans Al Rashid ◽  
Ramsha Imran ◽  
Zia Ullah Arif ◽  
Muhammad Yasir Khalid
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Finite Element Simulation ◽  
Crack Closure ◽  
Low Cycle Fatigue ◽  
Simulation Technique ◽  
Experimental Results ◽  
High Plasticity ◽  
Cycle Fatigue ◽  
Element Simulation

Abstract The crack closure phenomenon is important to study as it estimates the fatigue life of the components. It becomes even more complex under low cycle fatigue (LCF) since under LCF high amount of plasticity is induced within the material near notches or defects. As a result, the assumptions used by the linear elastic fracture mechanics (LEFM) approach become invalid. However, several experimental techniques are reported on the topic, the utilization of numerical tools can provide substantial cost and time-saving. In this study, the authors present a finite element simulation technique to evaluate the opening stress levels for two structural steels (25CrMo4 and 30NiCrMoV12) under low cycle fatigue conditions. The LCF experimental results were used to obtain kinematic hardening parameters through the Chaboche model. The finite element analysis (FEA) model was designed and validated, following the fatigue crack propagation simulation under high plasticity conditions using ABAQUS. Crack opening displacement vs. stress data was exported from ABAQUS, and 1.5% offset method was employed to define opening stress levels. Numerical simulation results were compared with the experimental results obtained earlier through the digital image correlation (DIC) technique. To conclude, FEA could be a valuable tool to predict crack closure phenomena and, ultimately, the fatigue life of components. However, analysis of opening stresses using crystal plasticity models or extended finite element method (XFEM) tools should be explored for a better approximation in future studies.

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