Experimental investigation on new low cycle fatigue precision cropping process

2014 ◽  
Vol 229 (8) ◽  
pp. 1470-1476 ◽  
Author(s):  
Renfeng Zhao ◽  
Shengdun Zhao ◽  
Bin Zhong ◽  
Yong Tang
Keyword(s):  
Stress Concentration ◽  
Cross Sections ◽  
Low Cycle Fatigue ◽  
Fatigue Loading ◽  
High Energy ◽  
Concentration Effect ◽  
Cycle Fatigue ◽  
Stable Crack Propagation ◽  
New Type ◽  
Stress Concentration Effect

The traditional cropping processes have some disadvantages, such as poor surface quality, low yield, the waste of materials, and high energy consumption. The low cycle fatigue precision cropping process with circumferential loading, which is a new type of precision cropping process, is studied. According to the stress concentration effect of the V-shape notch, the fatigue crack on the tip of the V-shape notch is prompted to initiate and extend. The working principle of the precision cropping machine is described. The criterion that whether the crack on the root of the V-shape notch is initiated or not is provided under the effect of low cycle fatigue loading. The materials which are 0.2%C steel, H59 copper, 0.45%C steel, 20Cr steel, and LY12 aluminum are tested under two control curves. The initiation and propagation of crack are accelerated and the good cross sections of the metal bar are obtained. The results show that the mean stress of the metal bar in the cropping process can be effectively reduced due to the stress concentration effect of the V-shape notch. The metal bar’s stable crack propagation and fracture can be obtained when constantly increasing striking displacement and reducing the striking frequency in the cropping process at the same time in the process.

Enhancing weak magnetic field MME coupling in NdFeB magnet/piezoelectric composite cantilevers with stress concentration effect

2021 ◽  
Vol 118 (13) ◽  
pp. 132902
Author(s):  
Zhonghui Yu ◽  
Zhaoqiang Chu ◽  
Jikun Yang ◽  
Mohammad Javad Pourhosseini Asl ◽  
Zhanmiao Li ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Stress Concentration ◽  
Weak Magnetic Field ◽  
Concentration Effect ◽  
Piezoelectric Composite ◽  
Ndfeb Magnet ◽  
Stress Concentration Effect

A Multi-Level Low Cycle Fatigue Damage Model for Forging Die Material

2006 ◽  
Vol 514-516 ◽  
pp. 804-809
Author(s):  
S. Gao ◽  
Ewald Werner
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Damage Model ◽  
Fatigue Loading ◽  
Cycle Fatigue ◽  
Die Material ◽  
Multi Level ◽  
Loading Sequence ◽  
Forging Die

The forging die material, a high strength steel designated W513 is considered in this paper. A fatigue damage model, based on thermodynamics and continuum damage mechanics, is constructed in which both the previous damage and the loading sequence are considered. The unknown material parameters in the model are identified from low cycle fatigue tests. Damage evolution under multi-level fatigue loading is investigated. The results show that the fatigue life is closely related to the loading sequence. The fatigue life of the materials with low fatigue loading first followed by high fatigue loading is longer than that for the reversed loading sequence.

Deformation Mechanisms of CoCrFeMnNi High-Entropy Alloy Under Low-Cycle-Fatigue Loading

2021 ◽  
Author(s):  
Kaiju Lu ◽  
Ankur Chauhan ◽  
Aditya Srinivasan Tirunilai ◽  
Jens Freudenberger ◽  
Alexander Kauffmann ◽  
...  
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Loading ◽  
Deformation Mechanisms ◽  
High Entropy Alloy ◽  
Cycle Fatigue ◽  
High Entropy

Fatigue Behaviour of the Novel Titanium Alloys TIMETAL® 407 and TIMETAL® 412

2021 ◽  
Author(s):  
◽  
William Davey
Keyword(s):  
Crack Initiation ◽  
Titanium Alloys ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Charpy Impact ◽  
Fatigue Behaviour ◽  
High Energy ◽  
Process Window ◽  
Cycle Fatigue ◽  
The Impact

TIMETAL®407 (Ti-407) is a medium strength (~650MPa 0.2%YS) titanium alloy, recently developed by TIMET, in conjunction with Rolls-Royce plc for use in applications requiring high energy absorption at impact. Preliminary Charpy Impact (V notch) testing showed Ti-407 to absorb nearly twice the impact energy of Ti-6-4 and exhibit more than 2.5 times the lateral expansion. Further initial testing suggested the high cycle fatigue (HCF) run out stress of Ti-407 matches that of Ti-6-4 and other high strength alpha-beta titanium alloys. Ti-407 displayed more than double the tool life than that of Ti-6-4. The reduction in tool wear supports lower forces required for faster, more efficient machining. Compared to Ti-6-4, the relatively low elevated temperature flow stress, greater malleability and wide process window should allow Ti-407 to be processed with fewer reheats, while exhibiting reduced surface cracking and giving a consistently good surface finish. Optimised Ti-407 manufacturing processes should allow parts to be formed closer to net shape giving higher yields and requiring less machining to the components finished size. This project has evaluated HCF, as well as low cycle fatigue (LCF) and dwell fatigue crack initiation mechanisms in Ti-407, to clarify the effects of alloy chemistry, microstructural morphology and scale, and crystallographic texture. A derivative of Ti-407, Ti-412 (~750MPa 0.2%YS) was also tested towards the end of the project and helped to further elucidate understanding of the fatigue characteristics of the two alloys. Of interest was the strong HCF response displayed relative to the monotonic tensile strength. As well as the investigation into the crack initiation mechanisms, an assessment of crack propagation across a range of microstructural conditions was carried out on Ti-407 material.

Low Cycle Fatigue of Unidirectional Glass/Epoxy Composites

1999 ◽  
Author(s):  
V. M. Harik ◽  
J. R. Klinger ◽  
B. K. Fink ◽  
T. A. Bogetti ◽  
A. Paesano ◽  
...  
Keyword(s):  
Polymer Matrix Composites ◽  
Low Cycle Fatigue ◽  
Glass Fibers ◽  
Fatigue Loading ◽  
Large Strains ◽  
Matrix Composites ◽  
Cycle Fatigue ◽  
Degradation Rates ◽  
Characteristics Analysis ◽  
Stress Ratios

Abstract Low cycle fatigue (LCF) behavior of unidirectional polymer matrix composites (PMCs) reinforced with glass fibers is investigated. LCF conditions involve high loads reaching up to 90% of the material ultimate strength. LCF characterization of PMCs is carried out under tension-tension fatigue loading to identify the key physical phenomena occurring in PMCs under LCF conditions and to determine their unique characteristics. Analysis of experimental data indicates that finite strain rates, large strains and stress ratios may affect LCF behavior of PMC structures and the property degradation rates.

Theoretical Modeling of Steel Strip Reinforced Flexible Pipe With Swaging End Fitting by Taking Into Account Stress Concentration Effect

2019 ◽  
Author(s):  
Yifan Gao ◽  
Wei Chen ◽  
Yong Bai
Keyword(s):  
Stress Concentration ◽  
Internal Pressure ◽  
Steel Strip ◽  
Displacement Discontinuity ◽  
Concentration Effect ◽  
Elastic Model ◽  
Thin Wall ◽  
Burst Strength ◽  
Joint Area ◽  
Stress Concentration Effect

Abstract A new theoretical model was proposed to calculate the burst pressure of steel strip reinforced flexible composite pipes (steel strip PSP) based on the thin wall cylindrical shell theory and the squeeze pressure expression between layers was derived. The radial displacement discontinuity of pipe wall in pipe-end fitting joint area takes in account in this model which could result in Stress Concentration Effect (SCE) in reinforcement layers. The SCE is caused by swaging end fitting clamped tightly at the end of the pipe. The result of the hoop strain in the joint area calculated by this model is greater than the one calculated by the classic elastic model, which leads to relative conservative burst strength of the pipe. The hoop stress variation via internal pressure on innermost reinforcement layer is introduced to predict the burst strength of the pipe. As the stress in the joint area reaches its ultimate strength, the strain on the same layer in the point far away from this area (x→∞) is extracted and the corresponding internal pressure is obtained as the burst strength of the pipe. The calculated data from two models were compared with the experiment results and the proposed new model showed better accuracy than the classic elastic model. Final additional parametric studies were conducted, while the effect of the pipe diameter, the winding angle, the number and thickness of the reinforcement layer on the burst strength of the pipe were studied. Useful conclusions were drawn for the design and application of the steel strip PSP in offshore engineering.

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