Fatigue Analysis of Titanium Welded Joints Using Mesh-Insensitive Structural Stress Approach

2011 ◽  
Vol 66-68 ◽  
pp. 838-844
Author(s):  
Li Bin Fu ◽  
Xin Hua Yang ◽  
Ping Sha Dong ◽  
Rui Ming Ren
Keyword(s):  
Welded Joints ◽  
Fatigue Crack Initiation ◽  
Structural Stress ◽  
Characteristic Analysis ◽  
Fatigue Characteristic ◽  
Welded Structures ◽  
Fatigue Data ◽  
Stress States ◽  
First Time ◽  
Better Than

Mesh-insensitive structural stress approach is a robust method for fatigue characteristic analysis of welded structures and has been validated in correlating a large amount of published fatigue test of steel welded joints in the literature. Regarding Titanium welded joints, the combination of stress states and geometric shape can also lead to stress concentration that can result in fatigue crack initiation around the welded joints. This paper aims to analyze well-documented fatigue data of transverse and longitudinal fillet welded joints of Titanium using mesh-insensitive structural stress approach. This study is the first time using the approach for titanium fatigue data analysis. The results show that the employed method can correlate fatigue data of Titanium welded joints noticeably and make sense to understand the effect of thickness on fatigue life of the joints better than conventional methods.

Codes and Practice of Fatigue Design for Welded Structures

1999 ◽  
Author(s):  
Haruo Sakamoto
Keyword(s):  
Statistical Study ◽  
Welded Joint ◽  
Fatigue Testing ◽  
Fracture Probability ◽  
Structural Stress ◽  
Welded Structures ◽  
Testing Method ◽  
Japanese Industrial Standard ◽  
Fatigue Design ◽  
Fatigue Data

Abstract This paper describes the codes and practice for designing welded structures such as railroad truck frames. For designing the first configuration, rather simple criteria are desired, although most codes such as AWS. AISC, etc. are complex. They consist of a variety of welded joint categories, which make a designer feel uncomfortable when deciding the first configuration. Therefore, such codes are considered to be mainly used for the evaluation of designed and constructed structures, and not to be used for deciding the first configuration. The JIS (Japanese Industrial Standard) for a railroad truck frame is explained as an example of a simple code, and is compared with some fatigue data. This standard is thought to be useful for a designer. However, the result of this investigation suggests a modification of the JIS for obtaining more reasonable criteria. Desirable criteria should be simple for a designer and sufficiently safe for structures. Additional investigations on fatigue data of welded joints, a statistical study for desirable non-fracture probability, and methods of structural stress analysis are to be conducted in the future. A practical fatigue testing method is also needed for investigating the strength in a high cycle region such as 108.

Fatigue Life of Multi-Spot Welded Structures

2007 ◽  
Vol 348-349 ◽  
pp. 249-252
Author(s):  
Pietro Salvini ◽  
Francesco Vivio ◽  
Vincenzo Vullo
Keyword(s):  
Fatigue Life ◽  
Numerical Solution ◽  
Welded Joints ◽  
Structural Model ◽  
Fatigue Behaviour ◽  
Progressive Damage ◽  
Welded Structures ◽  
Accumulated Damage ◽  
Fatigue Data ◽  
Spot Welded

A procedure that makes use of a conventional stress value (ERS) is applied to spot welded joints. The ERS can be evaluated for every spot weld of the structural model. Through the use of ERS-N curves, fatigue data performed on different joint geometries can be successfully mixed together. One of the main aspects is that progressive damage deeply influences fatigue behaviour, so that a simple numerical solution neglecting accumulated damage is unable to foresee the whole fatigue life. In the present paper the method has been applied to many experimental results: it is shown that a unique criterion is able to deal with several different structures and materials.

scholarly journals Effect of Antibacterial Root Canal Sealer on Persistent Apical Periodontitis

Antibiotics ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 741
Author(s):  
Zheng Wang ◽  
Ge Yang ◽  
Biao Ren ◽  
Yuan Gao ◽  
Xian Peng ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Therapeutic Effect ◽  
Root Canal ◽  
Apical Periodontitis ◽  
Control Group ◽  
Root Canal Sealer ◽  
Root Canal Filling ◽  
First Time ◽  
Cone Beam Computer Tomography ◽  
Better Than

The infection of Enterococcus faecalis and its interacting microorganisms in the root canal could cause persistent apical periodontitis (AP). Antibacterial root canal sealer has favorable prospects to inhibit biofilms. The purpose of this study was to investigated the antibacterial effect of root canal sealer containing dimethylaminododecyl methacrylate (DMADDM) on persistent AP in beagle dogs for the first time. Persistent AP was established by a two-step infection with Enterococcus faecalis and multi-bacteria (Enterococcus faecalis, Lactobacillus acidophilus, Actinomycesnaeslundii, Streptococcus gordonii). Root canal sealer containing DMADDM (0%, 1.25%, 2.5%) was used to complete root canal filling. The volume of lesions and inflammatory grade in the apical area were evaluated by cone beam computer tomography (CBCT) and hematoxylin-eosin staining. Both Enterococcus-faecalis- and multi-bacteria-induced persistent AP caused severe apical destruction, and there were no significant differences in pathogenicity between them. DMADDM-modified sealer significantly reduced the volume of periapical lesion and inflammatory grade compared with the control group, among them, the therapeutic effect of the 2.5% group was better than the 1.25% group. In addition, E.faecalis-induced reinfection was more sensitive to the 2.5% group than multi-bacteria reinfection. This study shows that root canal sealer containing DMADDM had a remarkable therapeutic effect on persistent AP, especially on E. faecalis-induced reinfection.

scholarly journals CPC2 Reduction with Hipparcos and Proper Motions in The Southern Hemisphere

1998 ◽  
Vol 11 (1) ◽  
pp. 551-551
Author(s):  
N. Zacharias ◽  
M.I. Zacharias ◽  
C. de Vegt ◽  
C.A. Murray
Keyword(s):  
Southern Hemisphere ◽  
Systematic Errors ◽  
Reference Star ◽  
Proper Motions ◽  
Positional Accuracy ◽  
Star Catalog ◽  
Naval Observatory ◽  
Celestial Reference System ◽  
First Time ◽  
Better Than

The Second Cape Photographic Catalog (CPC2) contains 276,131 stars covering the entire Southern Hemisphere in a 4-fold overlap pattern. Its mean epoch is 1968, which makes it a key catalog for proper motions. A new reduction of the 5687 plates using on average 40 Hipparcos stars per plate has resulted in a vastly improved catalog with a positional accuracy of about 40 mas (median value) per coordinate, which comes very close to the measuring precision. In particular, for the first time systematic errors depending on magnitude and color can be solved unambiguously and have been removed from the catalog. In combination with the Tycho Catalogue (mean epoch 1991.25) and the upcoming U.S. Naval Observatory CCD Astrograph Catalog (UCAC) project proper motions better than 2 mas/yr can be obtained. This will lead to a vastly improved reference star catalog in the Southern Hemisphere for the final Astrographic Catalogue (AC) reductions, which will then provide propermotions for millions of stars when combined with new epoch data. These data then will allow an uncompromised reduction of the southern Schmidt surveys on the International Celestial Reference System (ICRS).

scholarly journals Investigation of Solubility Behavior of Canagliflozin Hydrate Crystals Combining Crystallographic and Hirshfeld Surface Calculations

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 298
Author(s):  
Yefen Zhu ◽  
Yanlei Kang ◽  
Ling Zhu ◽  
Kaxi Yu ◽  
Shuai Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Intermolecular Forces ◽  
Hirshfeld Surface ◽  
Reversible Inhibitor ◽  
Solubility Behavior ◽  
Hydrogen Bond Networks ◽  
Solvent Molecules ◽  
First Time ◽  
Better Than

Canagliflozin (CG) was a highly effective, selective and reversible inhibitor of sodium-dependent glucose co-transporter 2 developed for the treatment of type 2 diabetes mellitus. The crystal structure of CG monohydrate (CG-H2O) was reported for the first time while CG hemihydrate (CG-Hemi) had been reported in our previous research. Solubility and dissolution rate results showed that the solubility of CG-Hemi was 1.4 times higher than that of CG-H2O in water and hydrochloric acid solution, and the dissolution rates of CG-Hemi were more than 3 folds than CG-H2O in both solutions. Hirshfeld surface analysis showed that CG-H2O had stronger intermolecular forces than CG-Hemi, and water molecules in CG-H2O participated three hydrogen bonds, forming hydrogen bond networks. These crystal structure features might make it more difficult for solvent molecules to dissolve CG-H2O than CG-Hemi. All these analyses might explain why the dissolution performance of CG-Hemi was better than CG-H2O. This work provided an approach to predict the dissolution performance of the drug based on its crystal structure.

Research of the Workpiece-Stage Control System Based on the ACR9000 in the Composite Coating Equipment of MEVVAII and FAD

2013 ◽  
Vol 668 ◽  
pp. 410-414
Author(s):  
Rui Xia Zhang ◽  
Bin Liao ◽  
Zhi Guo Liu ◽  
Xian Ying Wu
Keyword(s):  
Control System ◽  
Servo Control ◽  
Uniform Rotation ◽  
Coating Films ◽  
Servo Control System ◽  
Motion Modes ◽  
Speed Rotation ◽  
Micro Tools ◽  
First Time ◽  
Better Than

In order to realize the extensive application of technologies of MEVVAII and FAD, the composite equipment has been developed for surface modification and coating films. In this paper, for the first time, the servo control system based on ACR9000 has been used to control workpiece-stage of the composite equipment. Eight target disks are installed on workpiece-stage. Each of target disks can be mounted about 1300 PCB micro tools. So, the equipment can satisfy the requirement for mass production. Experimental results show that the coating unevenness is less than ±14%, better than those of traditional equipments which is less than ±29%. The main purpose of the paper is to introduce the design of workpiece-stage and its three motion modes of rotary positioning, uniform rotation and variable speed rotation, and coating effects corresponding to three motion modes have been verified by experiments.

scholarly journals DEVELOPMENT OF A TECHNOLOGICAL PROCESS FOR MANUFACTURING WELDED STRUCTURES

2021 ◽  
Vol 4 (5) ◽  
pp. 35-44
Author(s):  
R. El'cov
Keyword(s):  
Phase Composition ◽  
Laser Welding ◽  
Strain Amplitude ◽  
Welded Joints ◽  
Structural Phase ◽  
Diagnostic Methods ◽  
Aluminum Lithium ◽  
Aluminum Lithium Alloys ◽  
First Time ◽  
Lithium Alloys

the main goal of this article is to obtain welded permanent joints of modern thermally hardened aluminum and aluminum-lithium alloys made by laser welding, having mechanical characteristics (temporary tensile resistance, yield strength, elongation at break) and structural-phase composition close to or equal to the base alloy. It is shown for the first time that by controlling the parameters of heat treatment of samples with a welded joint of all studied aluminum-lithium alloys, it is possible to purposefully influence the formation of the specified mechanical properties of the weld by changing the structural and phase composition of the weld. The evolution of the struc-tural and phase composition of welded joints of thermally hardened aluminum and aluminum-lithium alloys has been investigated using modern independent diagnostic methods: for the first time, the use of synchrotron radia-tion diffractometry in combination with high-resolution transmission, scanning electron and optical microscopy. The dependences of the increment of deformation under cyclic loading with amplitudes exceeding the elastic limit on temperature are established. For untreated welded joints, it was found that at +85 C, the inhomogeneity of the deformation increment increases, and its speed increases by 8 times for alloy 1461, 5 times for alloy 1420 and 1.5 times for alloy 1441. At a temperature of -60 0C, alloys 1420 and 1461 have hardening stages, during which the value of deformation decreases at given boundary stress values. At +20 0C, there is a uniform increment of defor-mation and an increase in the amplitude of deformation with an increase in the amplitude of stress. At +85 0C, the strain amplitude does not change with increasing stress amplitude, its value is 0.55-0.5 of the strain amplitude at +20 0C. Based on the research results, technological techniques have been developed that allow obtaining me-chanical characteristics and structural-phase compositions of welded joints close to the main alloy during laser welding of aviation thermally hardened aluminum and aluminum-lithium alloys of the Al-Mg-Cu. Al-Mg-Li, Al-Cu-Mg-Li, Al-Cu-Li systems.

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