{"title":"A Study on the Unification of the Threshold Stress Intensity Factor for Micro Crack Growth","authors":"K. Ando, R. Fueki, K. Nam, K. Matsui, Koji Takahashi","doi":"10.5346/trbane.2019.39","DOIUrl":"https://doi.org/10.5346/trbane.2019.39","url":null,"abstract":"1. 緒 言 近年の線形破壊力学の進歩により,き裂問題のかなり の事象を応力拡大係数(K値) で定量的に取り扱えるように なった.すなわち,ぜい性き裂発生条件1), 2),疲労き裂3), 水素ぜい性き裂4)および応力腐食割れ5), 6)などのき裂成長 速度は解明された.また,それらの知見を活用して,欠陥 評価を行う規格が制定され,実用に供されている5)~9). しかし,線形破壊力学では,等方・均質・弾性体を仮定 しているために,き裂先端部に形成される非線形領域の寸 法がき裂長さに比べて,十分小さくないときには,長いき 裂の下限界K値に比し,それよりかなり小さいK値(疲労の 場合にはΔK)でき裂の成長が起こる.非線形領域の例 としては,金属では塑性域や粗大結晶粒が,セラミックス では,ごく微細なき裂の分散域や結晶粒の影響が指摘され ている11)~13).この問題は,微小き裂の下限界値問題と呼 ばれており,金属の疲労限度の場合には,早くからその特 性がほぼ解明され,有意義な提案が行われている10),14)~17). 金属のぜい性破壊に関しては,疲労限度に比べてやや遅れ たが,微小き裂の下限界値問題に関して,非線形領域の影 響を正視した先駆的研究がおこなわれている1). 一方,構造用セラミックスは,典型的なぜい性材料と考 えられていたが,微小き裂に対しては,平面ひずみ破壊じ ん性値KICが適用できないことが示されている.そ の結果を勘案し,プロセスゾーン破壊基準が提案され,そ の特性を良く説明できることが示されている11),12). 上述のごとく,疲労限度やぜい性破壊の微小き裂の下限 界値問題に関しては,多くの研究が実施10)~12), 14)~17)され ているが,ぜい性破壊,疲労破壊,水素ぜい性及び応力腐 食割れなどのき裂を統一した考えによる微小き裂問題の解 明は実施されていない.そこで,筆者らは,ぜい性破壊, 疲労破壊,水素ぜい性及び応力腐食割れ等のき裂を統一的 に取り扱える微小き裂の下限界値問題を検討することとし た.","PeriodicalId":406647,"journal":{"name":"Transactions of Japan Society of Spring Engineers","volume":"606 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116386383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effect of Compression Holding Time to Anelastic Residual Displacement of Steel Compression Coil Spring","authors":"S. Kotake, Y. Sano","doi":"10.5346/trbane.2019.53","DOIUrl":"https://doi.org/10.5346/trbane.2019.53","url":null,"abstract":"","PeriodicalId":406647,"journal":{"name":"Transactions of Japan Society of Spring Engineers","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128197734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The shape memory alloy (SMA) is expected to be applied as intelligent materials since it shows the unique characteristics of the shape memory effect and superelasticity. In the growing number of TiNi SMA applications, these materials should fulfill high requirements of fatigue, corrosion and wear resistance. On the other hand, the application of SMA has some limitations, particularly in thermomechanical cyclic loading cases. In these cases, fatigue of SMA is one of the important properties in view of evaluating functional characteristics as SMA elements. The study on enhancement of the fatigue life for TiNi SMA by ultrasonic-shot peening (USP) has not been investigated till now. In particular, since impressions appear little by USP in the region of superelasticity, the influence of USP on the fatigue life is not clear. In this paper, we report and discuss the influence of USP shot media diameter d and coverage c on the bending fatigue life of TiNi SMA tape which shows superelasticity.
{"title":"Influence of Ultrasonic Shot Peening on Fatigue Life of TiNi Shape Memory Alloy Wire","authors":"K. Takeda, Daiki Uemura, K. Hattori","doi":"10.5346/trbane.2019.33","DOIUrl":"https://doi.org/10.5346/trbane.2019.33","url":null,"abstract":"The shape memory alloy (SMA) is expected to be applied as intelligent materials since it shows the unique characteristics of the shape memory effect and superelasticity. In the growing number of TiNi SMA applications, these materials should fulfill high requirements of fatigue, corrosion and wear resistance. On the other hand, the application of SMA has some limitations, particularly in thermomechanical cyclic loading cases. In these cases, fatigue of SMA is one of the important properties in view of evaluating functional characteristics as SMA elements. The study on enhancement of the fatigue life for TiNi SMA by ultrasonic-shot peening (USP) has not been investigated till now. In particular, since impressions appear little by USP in the region of superelasticity, the influence of USP on the fatigue life is not clear. In this paper, we report and discuss the influence of USP shot media diameter d and coverage c on the bending fatigue life of TiNi SMA tape which shows superelasticity.","PeriodicalId":406647,"journal":{"name":"Transactions of Japan Society of Spring Engineers","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129089896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"An Innovative Large Deformation Method for Measuring Young’s Modulus in a Thin Flexible Multi-layered Material (Own-weight Multi-layered Circular Ring Method)","authors":"A. Ohtsuki, G. Sho","doi":"10.5346/TRBANE.2018.53","DOIUrl":"https://doi.org/10.5346/TRBANE.2018.53","url":null,"abstract":"1. 緒 言 大きなたわみ変形を示す薄肉材料(金属系の薄板/細線, 高分子材料など)がばね用部材あるいは機械構造用部材と して広く使用され,しかもばね性能の向上のために積層化 されて使われることも多い.ばねなどにおいては,防錆の みならず強度改善のため施されるめっき処理材などが代表 例である.こうした薄肉積層材料の強度設計においては, 積層を構成する各層の個々のヤング率(縦弾性係数)を知る ことが工業的に極めて重要であって,積層材料全体を単一 体と見做して近似的,平均的なヤング率で充当するのは適 切でないといえる.また,構成薄肉積層材料のヤング率自 体も成形プロセスに起因しバルク材のそれとは異なること が多く,バルク材のヤング率をそのまま利用して積層時の ヤング率を推定するにはいささか懸念がある.したがって, こういった積層材料の実測のヤング率が必要なのである が,これらの薄い,細い積層材料は低剛性のため, 微小変 形を基礎とする従来の規格化された材料試験法(引張試験 円リングにおける自重大たわみ変形を利用した薄肉積層材料の 新ヤング率測定法(自重大変形積層円リング法)*","PeriodicalId":406647,"journal":{"name":"Transactions of Japan Society of Spring Engineers","volume":"2018 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125565468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fatigue Property of High Strength Steel with Artificial Defects under Cyclic Torsion with a Shear Stress Ratio of 0.1","authors":"M. Hayakawa, S. Teramoto, S. Kozawa, Y. Neishi, T. Makino","doi":"10.5346/TRBANE.2018.5","DOIUrl":"https://doi.org/10.5346/TRBANE.2018.5","url":null,"abstract":"ここで,τwはせん断疲労限度[MPa],HVは母材のビッカー ス硬さ, area は最大主応力方向に投影した欠陥寸法の面 積の平方根[μm],Fは応力特異場の形状補正係数で表面 欠陥のアスペクト比 b/a の関数である.この予測式は,簡 便に疲労限度を見積もることができるため,コイルばねの 疲労強度設計に広く適用可能である. また,疲労強度に及ぼす微小欠陥寸法の影響について, Haddadらの提唱した潜在き裂長さによるモデル化がなさ れている3),4).これは平滑材には材料組織固有の潜在き裂 が存在すると仮定したモデルである.この潜在き裂の物理 的な意味については不明確であるものの,実験事実を良く 整理でき,曲げや軸力負荷に対しては材料特性を定量的に 評価できる長所がある.しかし,式(1)のモデル,Haddad らのモデルのいずれも主に回転曲げ疲労試験の結果を基に 回帰して構築された経験式であり2),3),5)~7),微小欠陥を有 する高強度鋼を対象とした片振りせん断繰返し負荷条件へ の適用には議論の余地があり,実験的検証が必要である. 本研究では,高強度鋼のねじり疲労限度に及ぼす欠陥 寸法の影響を明らかにすることを目標に,丸棒表面に異 なる寸法の人工微小欠陥を導入した試験片を用いて,片 振りねじり疲労試験を実施した.疲労試験後の破面SEM 観察から欠陥寸法を測定し,欠陥寸法と疲労限度の関係 を評価した.さらに,き裂長さを欠陥寸法投影面積に修 正したHaddadらのモデルを用いて,試験結果を整理し た. 人工欠陥を有する高強度鋼の片振りねじり疲労特性 *","PeriodicalId":406647,"journal":{"name":"Transactions of Japan Society of Spring Engineers","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116286804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
is an important phenomenon for spring technology, since it affects the size and restoring force of a spring during its operation. Although this property has been known more than a half-century ago, its mechanism has not been clarified yet. In this study we have evaluated the effects of magnetic treatments to the anelasticity of steel compression coil springs during elastic deformation in experiments. We measured the temporal change of recovery lengths of the specimens after unloading with or without magnetic stirring under 180mT, since free length change of the coil spring is the summation of the faint twist modification in the steel wire. Each spring of 20mm long showed about 20 μ m length of recovery in 2 hours from the point of 90 second after the unloading. It indicates some bowing-out dislocations during the compression were interrupted with certain disturbances. The length of recovery was increased in 10 ％ for the magnetic stirring specimens. Since alternatively changed external magnetic field expands the length of magnetic domain walls in steel, it suggests the walls might play the role of obstacles, such as weak pinning sites, against the recovery movement of the dislocations in anelasticity.
{"title":"Effect of Magnetic Stirring to Anelasticity of Steel Compression Coil Spring (Role of magnetic domain walls for weakly pinning dislocations)","authors":"S. Kotake, Takuro Murata","doi":"10.5346/TRBANE.2018.41","DOIUrl":"https://doi.org/10.5346/TRBANE.2018.41","url":null,"abstract":"is an important phenomenon for spring technology, since it affects the size and restoring force of a spring during its operation. Although this property has been known more than a half-century ago, its mechanism has not been clarified yet. In this study we have evaluated the effects of magnetic treatments to the anelasticity of steel compression coil springs during elastic deformation in experiments. We measured the temporal change of recovery lengths of the specimens after unloading with or without magnetic stirring under 180mT, since free length change of the coil spring is the summation of the faint twist modification in the steel wire. Each spring of 20mm long showed about 20 μ m length of recovery in 2 hours from the point of 90 second after the unloading. It indicates some bowing-out dislocations during the compression were interrupted with certain disturbances. The length of recovery was increased in 10 ％ for the magnetic stirring specimens. Since alternatively changed external magnetic field expands the length of magnetic domain walls in steel, it suggests the walls might play the role of obstacles, such as weak pinning sites, against the recovery movement of the dislocations in anelasticity.","PeriodicalId":406647,"journal":{"name":"Transactions of Japan Society of Spring Engineers","volume":"84 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114659123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A non-circular wire helical spring generally has a high spring constant and reduces the spring height at fully compressed condition, although the energy absorption decreases during deformation. For improving this energy absorption, we have applied Fe-Mn-Si based alloy （ FMS ） to the spring. FMS that is one of the shape memory alloys （ SMA ） have more reasonable and workable than any other type of the SMAs, e.g. Ti-Ni alloy. Its shape memory effect and super elasticity that are caused with the stress-induced γ（ Austenite ）⇔ ε martensitic transformation have been studied for. The cycled tensile tests are conducted on the springs made of FMS, S45C and SUS304. The load-displacement curve of FMS obtained by the cycled tensile test indicates a reversible large hysteresis loop. This is caused by deformation in two different processes of stress-induced martensitic transformation at loading, and reverse transformation at unloading. The non-circular wire helical spring of FMS is able to absorb more energy in early stage during large deformation than of S45C and SUS304.
{"title":"Large Deformation Behavior of Non-circular Wire Helical Spring with the Fe-based Shape Memory Alloy","authors":"Satoru Manzaki, Tomoaki Niwa, M. Notomi","doi":"10.5346/TRBANE.2018.63","DOIUrl":"https://doi.org/10.5346/TRBANE.2018.63","url":null,"abstract":"A non-circular wire helical spring generally has a high spring constant and reduces the spring height at fully compressed condition, although the energy absorption decreases during deformation. For improving this energy absorption, we have applied Fe-Mn-Si based alloy （ FMS ） to the spring. FMS that is one of the shape memory alloys （ SMA ） have more reasonable and workable than any other type of the SMAs, e.g. Ti-Ni alloy. Its shape memory effect and super elasticity that are caused with the stress-induced γ（ Austenite ）⇔ ε martensitic transformation have been studied for. The cycled tensile tests are conducted on the springs made of FMS, S45C and SUS304. The load-displacement curve of FMS obtained by the cycled tensile test indicates a reversible large hysteresis loop. This is caused by deformation in two different processes of stress-induced martensitic transformation at loading, and reverse transformation at unloading. The non-circular wire helical spring of FMS is able to absorb more energy in early stage during large deformation than of S45C and SUS304.","PeriodicalId":406647,"journal":{"name":"Transactions of Japan Society of Spring Engineers","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116772420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Sumi, K. Yokota, Mototsugu Osaki, H. Takabayashi, Gou Toyoda, Takayuki Akizuki, T. Omori, K. Ishida
Recently, the demand for improved efficiency of combustion engines is rising with the strict emission constraint. Therefore the requirement for heat resistance is increasing for materials used for springs in automobile exhaust system because the exhaust gas temperature becoming higher. Co-W-Al alloys precipitation-strengthened with the γ’ phase have good high temperature strength and considered to have potential for higher temperature application than conventional Ni base super-alloys. However, for coil spring application, materials must have enough workability in hot and cold roll to make coil wire. In order to enhance hot workability and high temperature mechanical properties, Ni and Cr were added and the optimization was performed in the chemical composition of Co-Ni-Cr-W-Al alloy. In this article, optimization of chemical composition, and relaxation property of coil spring of the developed “ COWALOY ® ” are reported.
{"title":"Development of Co-Ni-Cr-W-Al Alloy for Heat Resistant Springs","authors":"Y. Sumi, K. Yokota, Mototsugu Osaki, H. Takabayashi, Gou Toyoda, Takayuki Akizuki, T. Omori, K. Ishida","doi":"10.5346/TRBANE.2018.1","DOIUrl":"https://doi.org/10.5346/TRBANE.2018.1","url":null,"abstract":"Recently, the demand for improved efficiency of combustion engines is rising with the strict emission constraint. Therefore the requirement for heat resistance is increasing for materials used for springs in automobile exhaust system because the exhaust gas temperature becoming higher. Co-W-Al alloys precipitation-strengthened with the γ’ phase have good high temperature strength and considered to have potential for higher temperature application than conventional Ni base super-alloys. However, for coil spring application, materials must have enough workability in hot and cold roll to make coil wire. In order to enhance hot workability and high temperature mechanical properties, Ni and Cr were added and the optimization was performed in the chemical composition of Co-Ni-Cr-W-Al alloy. In this article, optimization of chemical composition, and relaxation property of coil spring of the developed “ COWALOY ® ” are reported.","PeriodicalId":406647,"journal":{"name":"Transactions of Japan Society of Spring Engineers","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124215069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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