-
Tetsuro NOSE, Hiroshi SHIMANUKI
Article type: Article
Session ID: 538
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Effects of ultrasonic peening on fatigue life of pad welded joint were analyzed by fatigue life analysis method by RPG load. It's noted that the ultrasonic peening is one of the most effective method for improving fatigue life of welded joint. Ultrasonic Impact Treatment, UIT was adopted in this study as the ultrasonic peening method. A significant increase in fatigue life was observed on the pad welded joint with UIT treated weld toe. The improvement was estimated mainly due to compressive residual stress introducing, stress concentration reducing and grain refining in weld toe area. Estimated fatigue life by FLARP was consistent with experimental result.
View full abstract
-
Koji GOTOH, Akira SUEDA, Masahiro TOYOSADA
Article type: Article
Session ID: 3539
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Precise prediction of fatigue crack growth is important to maintain the integrity of structures, because many fatigue damages are reported in welded built-up structures. The authors have developed the numerical fatigue crack growth (initiation and propagation) simulation code FLARP (Fatigue Life Assessment by RPG load) and shown its validity for fatigue test specimens and simple welded joints under constant and variable amplitude loadings. In this paper, the numerical fatigue crack growth simulations by FLARP for the structural elements with bracket are reported. The validity of fatigue life estimation by FLARP is confirmed by comparing the estimated S-N curves with the experimental results for the structures.
View full abstract
-
Masahiro GOTO, Seung-Zeon HAN, Terutoshi YAKUSHIJI, Cha-Yong Lim
Article type: Article
Session ID: 3540
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
-
Atsushi Sugeta, Yoshihiko Uematsu, Kohji Minoshima
Article type: Article
Session ID: 3541
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Fatigue strength at elevated temperatures were investigated using ultra-fine grained P/M (Powder Metallurgy) aluminum alloy of which grain size was from 200 to 500nm. Reversed plane bending fatigue tests were conducted at three different temperatures of room temperature (R.T.) and 250℃ (523K), and crack initiation and small crack growth were studied in detail by means of replication technique. The effect of pre-plastic working on fatigue strength was investigated using the three kinds of P/M Al alloys which were upset forging ratios. The dependence of fatigue strength on temperature was much smaller than that of conventional Al alloys. The crack initiated at the boundary between powders regardless of forging rations.
View full abstract
-
Yoshihiro MATSUYAMA, Norio KAWAGOISHI, Yuzo NAKAMURA, Eiji KONDO, Kazu ...
Article type: Article
Session ID: 3452
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Rotating bending fatigue tests were carried out for Inconel 718 at 500℃ in order to investigate the effect of grain size on the propagation behavior of a fatigue crack. Fatigue strength was higher in fine grained material than in coarse grained one. However, the resistance to crank growth was higher in coarse grained material than in fine grained one. The difference in fatigue strength in both materials can be explained by the retardation of small crack growth and the crack growth resistance.
View full abstract
-
Keiro TOKAJI, Takao HORIE, Yuuya ENOMOTO
Article type: Article
Session ID: 3543
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Corrosion fatigue behaviour was studied on high V-Cr-Ni cast irons with different microstructures in 3%NaCI aqueous solution. The fatigue strengths in 3%NaCI aqueous solution were nearly the same as those in laboratory air in short life regime, but fatigue failure took place at stresses below the fatigue limit in laboratory air. Corrosion pits generated at VCs, within lamellar microstructure, and at the boundary between those phases and austenitic matrix microstructure. Cracks initiated relatively much earlier due to the growth and coalescence of corrosion pits, but subsequent crack growth was considerably slower than in laboratory air due to complicated crack path.
View full abstract
-
Rongguang WANG, Mitsuo KIDO, Tarou TOKUDA, Yoshiko SHINHARA, Yuu SATAK ...
Article type: Article
Session ID: 3544
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
WC sprayed coatings are often occurred the corrosion fatigue fracture under the aqueous solution, because corrosion pits generate at the interface between the coating and the substrate. This study focused on the spraying pressure as well as the powder composition. The mechanical, corrosion, and corrosion fatigue fracture properties were investigated for three thermal spray materials fabricated by a spray gun with variable pressure. The corrosion fatigue strength of a specimen coated by WC/NiCrMo-A was the highest in the three type of coated specimen. It is thought that the mechanochemical response was controlled by a combination of: (1) The residual compressive stress generated by high spraying pressure for decreasing the effective stress, and (2) Enhanced corrosion resistance resulting from easy passivation of the coating components.
View full abstract
-
[in Japanese], [in Japanese], [in Japanese], [in Japanese]
Article type: Article
Session ID: 3545
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In the present study, fatigue tests of Zr-based bulk metallic glass, Zr_<55>Cu_<30>Ni_5Al_10, were conducted, under fully reversed cyclic bending (R=-1), and the surfaces of the fatigued specimen were observed to elucidate the fatigue crack initiation mechanisms. From the surface observations of the fatigued specimen, a shear band was observed at the crack initiation site just after the crack initiation, but not before. The fatigue crack propagation tests were also conducted to examine the effect of stress ratio and loading frequency. The fatigue crack propagation rate was found to be controlled by the stress intensity range, ΔK, or its effective component, ΔK_<eff>, independent of the stress ratio and the loading frequency.
View full abstract
-
Salleh TUAN SUHAIMI, Shin-ichi NISHIDA, Nobusuke HATTORI
Article type: Article
Session ID: 3546
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Bake hardening steels benefit initially from a relatively low dislocation density and a controlled level of carbon and nitrogen in solution. This research has been carried out to study the effects of the mechanisms of strain ageing particularly on the mechanical properties of a very thin steel sheet. The material used for the present investigation is a 0.4mm thickness of ULCS with addition of titanium to stabilize interstitial carbon. The studied specimens include as-rolled, no pre-strain with bake hardening, pre-strain with and without bake hardening prior to tensile and fatigue tests. The specimens are treated in such a way in order to study the results with baseline microstructure, effect of pre-strain with and without bake hardening and to maximize C in solution with pre-strain and bake hardening process respectively.
View full abstract
-
Taisuke IWAKI, Koichi ASADA, Takashi MATSUMURA, [in Japanese], Ryo Ues ...
Article type: Article
Session ID: 3547
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Recently, because the micro-machine is noticed and electronic equipments are made much lighter and smaller, the demand for micro materials is increasing. The research which investigates the mechanical property of micro materials have been carried out. However the mechanical properties data of the micro materials obviously run short and the evaluation method of micro materials is different according to the researcher. Therefore, the establishment of the test method for the micro materials is very necessary. In this study, SUS304 thin sheets with thicknesses of 10μm and 20μm were used. Specimens were manufactured using electro-spark machining. Afterwards, the machined surface was polished. The fatigue tests were carried out using these specimens. As the results, it was seen that variation in fatigue lives of specimen with thickness of 10μm was larger than that with thickness of 20μm.
View full abstract
-
Hiroyoshi UCHIDA, Ryouji KONDOU, Kazuo KUNIYOSHI, Chobin MAKABE
Article type: Article
Session ID: 3548
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The fatigue crack propagation with unstable behavior of local slip deformation in A1050 and A6061 aluminum under the cyclic tensile loading are investigated. Delay and non-propagation mechanisms of fatigue crack under constant stress amplitude are studied in detail. Results of investigation shown that fatigue crack propagate by mode I in A6061 under the cyclic tensile loading. However, modes of crack propagation in A1050 became mixed mode, which combined with mode I and II being dependent on the testing conditions. Under the some experimental conditions, Delay of crack propagation phenomenon was observed in A1050. Difference of fatigue crack propagation are discussed from the viewpoint of unstable behavior of local multiple-slip deformation.
View full abstract
-
Kiyotaka MASAKI, Yasuo OCHI, Takashi MATSUMURA, Yuji SANO, Koichi AKIT ...
Article type: Article
Session ID: 3549
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
To evaluate the effects of laser peening without coating on high cycle fatigue property, rotate-bending fatigue tests were conducted on pre-cracked AC4CH casting aluminum alloy. As the results, fatigue crack propagation was prevented by LP treatment. Apparent maximum stress intensity factor at surface on LP treatment specimen was nearly equivalent to about 4 times of threshold stress intensity factor of long fatigue crack at AC4CH when the surface crack began propagation. The cause of this threshold stress intensity factor increasing was effect of compressive residual stress by LP treatment.
View full abstract
-
Terutoshi YAKUSHIJI, Kenji SAKAE, Yoshio ITSUMI, Tomofumi TANAKA
Article type: Article
Session ID: 3550
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Rotating bending fatigue tests of three kinds of Ti alloy which have different crystal structure were carried out. The results obtained are as follows. (1) Fatigue limit of the Ti alloys decreased with an increase in Mo content. As a result, the fatigue limit of β Ti alloy(non-ageing) was the lowest. This originates from the difference of the critical stress of crack initiation. (2) It became clear that a crack initiate at the boundary of the lath martensite and the boundary of the β grain. In the case of α' and α" Ti alloy, the cracks extend perpendicular to the axis of stress. on the other hand the crack of the β Ti alloy propagated in the grain boundary.
View full abstract
-
Toru HIRASAWA, Kiyotaka MASAKI, Yasuo OCHI, Takashi MATSUMURA, Kenji H ...
Article type: Article
Session ID: 3551
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In order to investigate fatigue property at two-step load conditions, rotate-bending fatigue tests were conducted on AZ31 extruded magnesium alloy with AZ31-30 (Grain size: 29μm) and AZ31-50(Grain size: 47μm). Then, the specific two-step load conditions were (δ_H,δ_L)=(160, 130) and (δ_H, δ_L)=(130, 100). As a result of evaluating with Modified Miner rule, the value of cumulative fatigue damage D of AZ31-50 were about 1.2. However, the value of AZ31-30 was lower than AZ31-50, it was about 1.0 except the case of δ_a=(130→100). Fatigue crack observation with replication technique and fracture observation by SEM were also carried out in order to investigate the results.
View full abstract
-
Masao Sakane, Kazuhiro Itoh, Yutaka Tsukada, Kenji Terada
Article type: Article
Session ID: 3552
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper studies the crack propagation at Sn37Pb-copper interface in push-pull low cycle fatigue. Bonded specimens of Sn37Pb and copper having notch holes with different distances from the interface were fatigued at 313K and the crack propagation paths were observed. Cracks propagated at the interface when the notch hole was near the interface but propagated in the solder when the notch hole was away from the interface. The propagation rate of the interface crack was faster than that of non-interface crack. The crack path and crack propagation rate of the two types of cracks were discussed in relation to J integral range calculated by finite element method.
View full abstract
-
Takeshi TERASAKI, Hisashi TANIE
Article type: Article
Session ID: 3553
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The fatigue life of solder joints can be reduced by voids in the joint. We developed a new crack propagation model for detecting crack propagation in the solder joints. In our model, the fatigue life of a solder joint is estimated based on the amount of damage that accumulates during crack propagation, and the crack paths are automatically calculated. We analyzed the effect of varying the void position on the crack paths and the fatigue life of a ball grid array (BGA) solder joint, which was connected with a solder-mask defined (SMD) pad and a non-solder-mask defined (NSMD) pad. The calculations revealed that a void adjacent to the SMD pad decreased the fatigue life and that a void adjacent to the NSMD pad increased the fatigue life. The crack paths and fatigue lives were found to strongly depend on void position.
View full abstract
-
Takamoto Itoh, Takaei Yamamoto, Masao Sakane, Tomoyuki Horii, Yutaka T ...
Article type: Article
Session ID: 3554
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes the multiaxial low cycle fatigue of Sn-8Zn-3Bi solder. Push-pull and reversed torsion proportional and non-proportional loading tests were carried out using 5 strain paths at a strain rate 0.5%/s on the von Mises basis. The effects of strain multiaxiality and non-proportionality on low cycle fatigue life were discussed. Non-proportional loading reduced the low cycle fatigue life of the solder resulting from the additional hardening by the non-proportional loading. The non-proportional strain, recently proposed by the authors, predicted the fatigue life under non-proportional loading within a factor of two band.
View full abstract
-
Masahiro ISHIBASHI, Yukari KAGA, Kenichi Ohguchi
Article type: Article
Session ID: 3555
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The fatigue and tensile tests were conducted for some lead-free solders (Sn-3Ag-0.5Cu, Sn-9Zn and Sn-8Zn-3Bi) and two types of lead-containing solder (Sn-37Pb, Sn-95Pb) at three temperatures (233K, 298K and 398K). It was found that the relationship between the maximum stress in these fatigue tests and the test temperatures normalized by each melting point are divided roughly into 3 groups. Moreover, for lead-free solders, we proposed a visco-plastic constitutive equation, whose total strain was calculated from the sum of the elastic strain, the plastic strain, and the creep strain. The constitutive equation was incorporated to the finite element method analysis software ANSYS. The simulation result using ANSYS was highly consistent with a result of the fatigue test of Sn-3Ag-0.5Cu solder.
View full abstract
-
Noritake HIYOSHI, Masao SAKANE, Yutaka TSUKADA
Article type: Article
Session ID: 3556
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper describes the creep-fatigue lives of Sn-3.5Ag solder at low temperatures. Push-pull creep-fatigue tests were carried out at 273K to examine the effect of temperature and strain rate on fatigue life. Slow tension-going straining was more detrimental to lifetimes than slow compression-going straining. Strain range partitioning (SRP) method was a suitable parameter for the correlation of creep-fatigue lives. The SRP method using 313K data predicted almost all of the experimental lifetimes within a factor of 2 scatter band. Many small cracks with roughened surface were observed in the specimen after tests.
View full abstract
-
Hiroyuki TAKAHASHI, Minoru MUKAI, Takashi KAWAKAMI
Article type: Article
Session ID: 3557
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Evaluation of reliability for the impact strength of solder joints have been coming an important issue related to the miniaturization, lightweight and multi-functionalization of portable information equipments. However, there are few data about the deformation characteristic and the strength property of lead-free solder at the high strain rate, which can be used as the basic data of stress analysis. In this study, the tensile tests at room temperature and 125℃ were carried out for Sn-3.OAg-0.5Cu lead-free solder, in order to investigate the tensile property in the strain range from low strain rate to high strain rate. As a result, it was found that the tensile strength increases with the increase in strain rate.
View full abstract
-
Ken-ichi OHGUCHI, Katsuhiko SASAKI, Setsuo ASO
Article type: Article
Session ID: 3558
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
To apply the lead-free solder alloys to the electronic equipment, the strength reliability of the lead-free solder joint must be evaluated by the accurate FEM analysis. Since the deformation behavior of lead-free solder alloys shows the time dependency, the FEM analysis often employs the constitutive models of the elasto-plastic-creep type. To conduct the high-accuracy analysis by using the constitutive model, the characteristics of the elastic, plastic and creep deformations of lead-free solder alloys should be evaluated accurately. Moreover, the evaluation should be conducted immediately because taking a long time for the evaluation delays the practical use of the lead-free solder alloys in the electronic equipment. In this study, we propose a method which can evaluate the characteristics of the elastic, plastic and creep deformations of lead-free solder alloys by conducting only one 1 test. The test was conducted under the stepped ramp wave loading which consists of the instantaneous straining parts and maintaining strain parts using Sn-3.OAg-0.5Cu lead-free solder alloys. The stress-strain relations at the instantaneous straining parts in the test are used for evaluating the elasto-plastic deformation, while the stress-time relations during the maintaining strain parts are used for evaluating the creep deformation.
View full abstract
-
Takuji KOBAYASHI, Katsuhiko SASAKI, Yoshihiro NARITA
Article type: Article
Session ID: 3559
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper conducts both experiments and numerical simulations of viscoplastic deformation such as creep and uniaxial ratcheting deformation of solder alloys. The correlation between creep and uniaxial ratcheting deformation is firstly discussed to establish the differences in the time-dependent deformation of lead-free and lead-containing solder alloys. The experiments show that the ratcheting deformation of lead-free solder alloy is much smaller than the lead-containing solder alloy. Especially, there is much difference in the effect of the uniaxial ratcheting on the creep deformation between the two solder alloys. Then numerical simulations are also carried out using the dislocation based constitutive model. There is amoderate agreement between experiment and simulation.
View full abstract
-
Takaaki NAKAMURA, Takeshi OGAWA, Tadasi OHSAWA, Tomio HAYASHI
Article type: Article
Session ID: 3560
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Although mechanical properties of solder have been evaluated by testing of bulk material in tension, applicability of this result is questionable because the in-service solder joints are extremely small. In this study, BGA specimens were made from in-service solder joints and compared with cast specimen from eutectic solder (Sn-37Pb). The mechanical properties were estimated by indentation method. Stress-strain curves were determined by dual indenter method for BGA and cast specimens. The results revealed that mechanical properties of solder joints depended on the size of microstructure. Therefore, when we estimate mechanical properties of in-service solder joints, test specimen should be made from the in-service solder joints itself.
View full abstract
-
Tatsuya NISHIYAMA, Takeshi OGAWA, Tadashi OHSAWA, Hiroo SAKAMOTO
Article type: Article
Session ID: 3561
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Au solders have been used for micro joints of electronic packaging where high reliability is required. However, data on mechanical properties of Au solders is very limited because the material is too expensive to make bulk tensile specimens. Especially, creep properties of Au solders have not been examined. We carried out indentation creep tests at various temperatures at R.T., 323K, 373K, 398K and 423K for Au-20Sn and Au-12Ge solders. It was found that creep deformation existed at room temperature for Au-20Sn, while it was seen above 373K for Au-12Ge. Plastic anisotropy of Au-12Ge was evaluated by dent shape. Nano-indentation tests were performed in order to investigate influence of each phases of Au-20Sn on creep deformation.
View full abstract
-
Daiki SHIOZAWA, Yoshikazu NAKAI, Masaki YOKOTA, Norihiro TERAMOTO
Article type: Article
Session ID: 3601
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The change on magnetic properties of sus304 stainless steel has been investigated in fatigue process. The distribution of magnetic field on the sus304 specimen was measured with MI sensor. It was found that the no change on magnetic field distribution was observed in the initial period of fatigue test. The peak of magnetic field intensity was observed before crack was initiated. The magnitude of this peak increases with increasing number of cycles. The location where peak value was observed at first coincides with the location of crack initiation. It was found that the fatigue damage could be evaluated by the change on measured magnetic field, such as the location, occurrence time and magnitude of peak of magnetic field intensity.
View full abstract
-
Masao HAYAKAWA, Koji YAMAGUCHI, Megumi KIMURA, Kazuo KOBAYASHI
Article type: Article
Session ID: 3602
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Microstructural analyses by FE-SEM and TEM were performed on a ferritic heat-resisting steel that contained 12mass% chromium and 2mass% tungsten to characterize its multi-scale structure, consisting of prior austenite grains, packets, blocks, subgrains and precipitates. The size distributions of the block, subgrains and precipitates were quantitatively evaluated before and after a creep-fatigue test to relate them to their creep-fatigue property. Our results showed that the occupancy of precipitates on prior austenite grain boundaries increased markedly and subgrains near grain boundaries became coarse during the creep-fatigue test, while block size did not change. It is suggested that the growth of grain boundary precipitates and coarse subgrains near grain boundaries plays an important role in the intergranular fracture mechanism caused by creep-fatigue.
View full abstract
-
Kazuo KOBAYASHI, Koji YAMAGUCHI, Masao HAYAKAWA, Megumi KIMURA
Article type: Article
Session ID: 3603
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
We investigated the fatigue properties at high temperatures of fine-grained and coarse-grained iron-base supperalloy A286 and nickel-base Alloy 718 as well as 304L. In the fine-grained alloys, the fatigue strengths were almost the same as the conventional steels, and approximately 0.5 by σ_w/σ_B, σ_W ; fatigue strength at 10^7 cycles, σ_B ; tensile strength. In contrast, the fatigue strength of the coarse-grained alloys decreased to 0.3 by σ_w/σ_B, because the fracture was initiated at the interior flat facets.
View full abstract
-
Nobuo NAGASHIMA, Saburo MATSUOKA
Article type: Article
Session ID: 3604
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Fully reversed total-axial-strain-controlled low cycle fatigue (LCF) tests have been conducted in air at room temperature on fine- and coarse-grain low-carbon steels, SUS304 steel and SUS316L steel. Three types of hardness measurements, namely nano-indentation, micro-indentation and conventional Vickers hardness tests, with the indentation size ranging from several tens of nm to several tens of μm, were performed for both virgin and fatigued specimens to evaluate the mechanical behaviour at different scales of the cyclically deformed steel during LCF. OM and TEM observation showed that the microstructural parameters are the dislocation cell size, d_<cell>, slip spacing, w_<slip>, and austenitic grain size, d_γ. Referring 10 d_<cell> and 10w_<slip>. Vickers hardness, HV, corresponding to macro strength was expressed as HV=Hv^*_<base>+Hv^*_<sol>+Hv^*_<cell>+Hv^*_<slip>. Hv^*_<base> is the base hardness, Hv^*_<sol> is the solid solution strengthening hardness, and Hv^*_<cell> and Hv^*_<slip> are the fine grain strengthening hardness due to the dislocation cell and slip band.
View full abstract
-
Hiroshi MATSUNO
Article type: Article
Session ID: 3605
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Fatigue strength data on metals are picked up from literature, and they are rearranged on the basis of the Equivalent Stress Ratio, which has been proposed by the author. The characteristics of fatigue strength are especially investigated for metals containing inclusions and phase-inhomogeneity. As a result, it is found that the σ_<w2> type fatigue strength is often exhibited even in a specimen without a notch and it leads to a wide range of scattering of fatigue strength of unnotched specimens.
View full abstract
-
Keiji YAMASHITA, Masahiro ENDO
Article type: Article
Session ID: 3606
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
A modified linear-elastic method of analysis proposed by McEvily et al. was used for the determination of fatigue strengths and fatigue lifetimes of biaxially loaded components containing defects. The method assumes that the fatigue strength and the fatigue lifetime are both controlled by small fatigue crack propagation, and that the fatigue cracks propagate as Mode I cracks. The modifications were made considering (1) the effect of elastic-plastic behavior ; (2) the Kitagawa-Takahashi effect ; and (3) the development of crack closure in the wake of a newly-formed crack. Experiments were carried out under combined cyclic loading conditions employing SCM435 steel specimens that contained surface defects of various sizes to check on the accuracy of the predictions. The predicted fatigue strengths as well as the predicted fatigue lives agreed reasonably with the experimental results.
View full abstract
-
Kazuhiko Okuya, Yosiyuki Konndo
Article type: Article
Session ID: 3607
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Earthquakes sometimes give damages to steel structures. The structures which have not been seriously damaged are still used after an earthquake. The fatigue strength of these structures, however, might have been decreased due to the cyclic loads during an earthquake. In order to clarify the effect of seismic loading on the fatigue strength of the welded joint of a steel structure, varying loading fatigue test of welded joint after large straining was performed. However, few researches have been done on the residual fatigue strength after large strain cycling which enters into gross plasticity. The objective of this study is to clarify the integrity evaluation method of steel structures which experienced seismic loading. The varying loading fatigue test of a welded joint which had been subjected to a large cyclic strain as a simulation of a seismic loading was conducted and the residual fatigue strength was investigated.
View full abstract
-
Hitoshi Toda, Kanou Miyao, Kunio Fukuyama
Article type: Article
Session ID: 3608
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The leaf spring has used by suspension for the truck and bus, because of their simple framework and endurance. On one hand, we know that the leaf spring is broken by the fretting fatigue, on the other, we don't know the danger of the leaf spring left on the load. In the present study, we introduce the case of the accident cause for broken leaf spring. And then we analysis the broken leaf springs left on the load. As the results, we confirmed the characteristic of fracture mode of the leaf spring. We hope that people perceive the danger of the leaf spring left on the load.
View full abstract
-
Chobin MAKABE, Anggit MURDANI, Akihide SAIMOTO, Ryouji KONDOU
Article type: Article
Session ID: 3609
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Drilling a hole at crack tip is one of the methods for arresting crack growth. This hole is called stopping hole. Some application studies for arresting crack growth were performed and the improvement of fatigue life of cracked material was shown. In the present study, also, the arresting method of crack growth was investigated with drilling plural holes at crack tips and in the vicinity of the crack tips. In some cases of drilling positions of holes, fatigue life became longer than the case that stopping holes only were drilled. This is related to the decreasing stress concentration at the stopping hole edges.
View full abstract
-
Masayuki AKITA, Masaki NAKAJIMA, Yoshihiko UEMATSU, Keiro TOKAJI
Article type: Article
Session ID: 3610
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Axial fatigue tests have been performed on a ferritic stainless steel type 444 in 3%NaCl solution and the effect of corrosive environment on fatigue behaviour was studied. Three materials with different microstructure were prepared by means of the heat treatments of annealing at 960℃ and 1000℃, and water-cooling at 960℃. In all the materials studied, the fatigue strengths at 10^7cycles in 3%NaCl solution decreased compared with those in laboratory air. In the annealed specimens, intergranular cracks were observed at low applied stresses, while in the water-cooled specimen, intergranular cracks initiated regardless of applied stress level. The crack initiation resistance decreased with increasing annealing temperature and the crack initiation resistance of the water-cooled specimen was lower than that of the annealed specimens. The same tendency was also recognized in crack growth resistance.
View full abstract
-
Fumito KAWAMURA, Masayuki NAKAHIRO, Ryuichiro EBARA
Article type: Article
Session ID: 3611
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Corrosion is a time dependent phenomenon. Therefore, strength of long term used steel structures decreases due to corrosion. Strength of corroded steel plates is evaluated by average thickness. However this method is not well evaluated. In this paper, measurement thickness and tensile tests were conducted by use of corroded steel plates of long term used for more than 50 years. Estimation of residual strength for corroded steel and applicability for actual structures were examined from the relation between section shape and residual strength corroded steel.
View full abstract
-
Satoru ODAHARA, Takayuki FUKUDA
Article type: Article
Session ID: 3612
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Fatigue failure by In-line flow-induced vibration was reproduced under the similar condition of sodium leakage accident in Fast Breeder Reactor MONJU. 0.45% carbon steel test specimen was fixed in acrylic tube of the water flow loop equipment. A drilled small hole was introduced onto the surface of the test specimen. Variation of the natural frequency and strain amplitude was measured at every moment. Due to the corrosion fatigue, specimen failure was occurred by In-line flow-induced vibration. This phenomenon is significant in designing the nuclear power plant.
View full abstract
-
Mitsuru ADACHI, Kouji OKUTANI, Norio KAWAGOISHI, Yoshikazu MAEDA, Eiji ...
Article type: Article
Session ID: 3613
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Rotating bending fatigue tests were carried out for a squeeze cast Al alloy AC4CH-T6, in order to investigate the effect of hydrogen in molten aluminum on fatigue properties. The hydrogen contents were 0.22 and 0.38cc/100gAl. Voids were increased with increase in hydrogen content. However, static strength, ductility and fatigue strength were hardly influenced by hydrogen content. Most fatigue life was occupied by the growth life of a small crack which was evaluated by the small crack growth law.
View full abstract
-
Sotomi ISHIHARA, Hisakimi NOTOYA, Takahito GOSHIMA
Article type: Article
Session ID: 3614
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Corrosion fatigue tests were performed using magnesium alloy with an electroless Ni plating. In laboratory air, effect of surface treatments (deposited, blasted and polished surface treatment) on fatigue life was minimal. While in 3% sodium environment, fatigue life of the specimen with an electroless Ni plating is shorter than those of the polished and blasted specimens.
View full abstract
-
Naoya TADA, Akira FUNAKOSHI, Yusuke ISHII
Article type: Article
Session ID: 3615
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In conventional direct-current potential difference method (DC-PDM), uniform current is supplied far from a crack and the change in the potential difference by the crack is measured. The identification of the crack is done based on it. But in the case of a crack on the back surface, the change is not large enough and the identification is usually difficult. In this study, auxiliary current is supplied in addition to the remote uniform current and the improvement of identification of the crack existing on the back surface is investigated using the finite element method. Based on the analysis results, effect of the location of the auxiliary current and its strength on the measured potential difference is discussed.
View full abstract
-
Takuya HATOU, Kazuya MORI, Masatoshi KURODA, Ippei TORIGOE
Article type: Article
Session ID: 3616
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The relationship between distribution of dynamic modulus of elasticity and frequencies of flexural vibration and longitudinal vibration in freezing and thawing concrete specimen were examined. We know experimentally that the dynamic modulus of elasticity obtained from the frequency of flexural vibration decreases rapidly more than that obtained from the frequency of longitudinal vibration. We assumed that this cause was non-uniform of dynamic modulus of elasticity. The relationship between the distribution of dynamic modulus of elasticity and the frequencies of those vibrations was obtained by finite element method. We proposed the method to determine the distribution of dynamic modulus of elasticity from the frequencies of flexural vibration and longitudinal vibration.
View full abstract
-
Seiichiro TSUTSUMI, Masahiro TOYOSADA
Article type: Article
Session ID: 3617
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In order to describe cyclic plasticity phenomena the plastic stretching within yield surface has to be considered. A subloading surface model categorized in the unconventional plasticity models and describing a smooth elastic-plastic transition would be applicable to non-proportional loading process including cyclic loading behavior of materials with a smooth yield surface. In this study the model is extended for materials exhibiting a purely elastic response under a particular state of stress state, named elastic boundary surface, whilst they also exhibit a smooth elastic-plastic transition. A damage evolution is also described by incorporating damage function for the conventional model.
View full abstract
-
Seiichiro TSUTSUMI, Koji MURAKAMI, Chiaki TOKUDA, Yuichi NAKAYAMA, Dai ...
Article type: Article
Session ID: 3618
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The deformation behaviors of round bars under monotonicand cyclic loading condition are simulated by using FE analysis in which a cyclic plasticity model, so-called initial subloading surface model, is incorporated. The subloading surface model describes a smooth elastic-plastic transition and is applicable to non-proportional loading process including cyclic loading behavior of materials with a smooth yield surface. In this study, several examples of FEM analysis on the cyclic deformation behaviour of round bars are presented to show the potential of the incorporated cyclic plasticity model.
View full abstract
-
Yoshio ARAI, Eiichiro TSUCHIDA, Tomoyuki OOTSUKA, Hiroshi SUZUKI, Tets ...
Article type: Article
Session ID: 3619
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Methods of optimum fatigue design for high pressure composite vessels are investigated through experimental and simulation approaches. Burst tests and cyclic pressure tests were conducted for a specially designed composite vessel. Fatigue behaviors of Al liner were observed and examined through simulated stress and strain state and its low cycle fatigue characteristics. The effects of CFRP layer thickness on the fatigue life of Al liner are presented in the context of optimum design.
View full abstract
-
Hitoshi SOYAMA, Noritaka MIYAMOTO
Article type: Article
Session ID: 3620
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Cavitation normally causes severe damage in hydraulic machinery such as pumps and valves so on. However, cavitation impact can be utilized to surface treatment to improve fatigue strength of metallic materials in the same way as shot peening. Peening using cavitation impact was named as "cavitation peening" or "cavitation shotless peening" as shots are not required. As increase of surface roughness induced by cavitation peening was relatively small comparing with that of shot peening, improvement of fatigue strength of light metallic materials would be better than that of shot peening. In the present paper, the aluminum alloy and the magnesium alloy treated by cavitation peening were tested by a rotating bending fatigue test. It was revealed that the fatigue strength of the aluminum alloy AC4CH and magnesium alloy AM60B were improved 40% and 20%, respectively.
View full abstract
-
Shin-ichi NISHIDA, Nobusuke HATTORI, Yusuke NAKABARU, Akemi TSUCHIYAMA
Article type: Article
Session ID: 3621
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
Rotating bending fatigue tests had been performed in order to investigate the influence of DLC coating on the fatigue properties of Ti-6Al-4V Four types specimen coated by different coating time were prepared for the fatigue test. The result showed that fatigue limit and internal hardness improved as the coating time becomes longer. It is considered that this result was due to compressive residual stress generated on the specimen's surface during the process of the DLC coating.
View full abstract
-
Tetsuya IKEDA, Hiromasa YAMAGUCHI, Kensuke ICHINOSE, Takao YAKOU, Kats ...
Article type: Article
Session ID: 3622
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
In this research, it was investigated that the relation between the material property of an aluminized steel and thickness of an aluminum used for the Aluminizing treatment. To obtain the oxidation resistance and abrasion resistance for steel, aluminizing treatments using aluminum on steel surface are performed. Thickness of a surface condition and alloy layer varied by changing thickness of the aluminums. Subsequently, the mechanical properties are obtained from tension tests. In the results, it was recognized that mechanical properties were improved in aluminized processing.
View full abstract
-
Takashi HONDA, Atsushi YAMAGUTI, Albert S. KOBAYASHI, Mamidala RAMULU
Article type: Article
Session ID: 3623
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The objective of this research was to determine the effect of surface roughness on fatigue strength in peened 7075-T7351 three point bend (TPB) specimens. Surface roughness of as-received and peened specimens (with four Almen scales (4, 8, 12, 16)) was measured with the laser microscope. All specimens were fatigued to failure at various stress levels, and a S-N diagram was constructed. The fatigue strength of 7075-T7351 was improved by shot peening, and the effect of shot peening on fatigue strength was inversely proportional to the shot intensity. Since the surface roughness in peened TPB specimens was proportional to shot intensity, the fatigue limits of peened specimens were evaluated by equivalent defect size √<area_R>, which is applied to irregularly shaped surface roughness. The fatigue limits evaluated by √<area_R> were agreed with experimental results well.
View full abstract
-
Sei UEDA, Toshiaki TAKAKI
Article type: Article
Session ID: 3639
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The thermoelectromechanical fracture problem for a symmetrical functionally graded piezoelectric slab containing a center crack parallel to the free boundaries is considered in this study. It is assumed that the thermoelectroelastic properties of the medium vary continuously in the thickness direction, and that the slab is under thermomechanical loadings. The crack faces are supposed to be insulated thermally and electrically. By using the Fourier transform, the thermal and electromechanical problems are reduced to singular integral equations, respectively, which are solved numerically. Numerical calculations are carried out, and detailed results are presented to illustrate the influence of the crack length and the material nonhomogeneity on the temperature-stress distributions and the stress intensity factor.
View full abstract
-
Mayuko MAEDA, Fumihiro ASHIDA, Sei-ichiro SAKATA
Article type: Article
Session ID: 3640
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
This paper deals with the one-dimensional generalized thermoelasticity in a homogeneous isotropic infinite thin plate exhibiting an inelastic behavior, when a damping effect is taken into account. The plate is initially at zero temperature and subjected to a ramp heating on the top surface. The governing equations for the temperature change, heat flux, particle velocity and axial stress are expressed by a set of first-order partial differential equations. This system of equations has been numerically analyzed by employing the method of characteristics. Finally, the effects of the damping coefficient on time histories of the axial stress and temperature change are illustrated graphically.
View full abstract
-
Toshiaki HATA
Article type: Article
Session ID: 3641
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
CONFERENCE PROCEEDINGS
RESTRICTED ACCESS
The elastodynamic response of the transformation-toughened ceramics under an instantaneous phase transformation by the thermal impact is investigated. Some composite materials, such as Zirconia toughened ceramics, are remarkable material, which has a high strength, a high elastic modulus, and an improved toughness, etc. Most of the good qualities are common in many ceramic composite materials. These good qualities are made possible through the phase transformation of composite particles. The transformation toughening utilizes the stress-induced phase transformation of particles, which is accompanied by a volumetric expansion. In this paper a phenomenological model is proposed to describe the situation, which involves a dynamic phase transformation in a spherical particle embedded in the infinite elastic matrix.
View full abstract
