Improvement of Random Fatigue Life Prediction in terms of Actual Fatigue Process-Oriented Fatigue Damage Counting Method

基于实际疲劳过程的疲劳损伤计数方法对随机疲劳寿命预测的改进

• 批准号: 06555030
• 负责人: HARADA Shoji
• 金额: $ 4.35万
• 依托单位: Kyushu Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Developmental Scientific Research (B)
• 财政年份: 1994
• 资助国家: 日本
• 起止时间: 1994 至 1995
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06555030/
• 关键词: Random Loading; Fatigue Life; Small Crack Growth; Crack Tip Opening Displacement; Rain Flow Method; ランダム疲労; 変動応力; 過小応力; き裂伝ぱ; き裂開閉口; 疲労寿命予測

To establish highly reliable fatigue life prediction method under random loading the rain flow method(RFM), originally developed as one of the most useful fatigue damage counting method, was re-interpreted by taking into account the actual fatigue process of crack initiation and propagation. Incounting fatigue damage, either cyclic plastic strain(LCF)or cyclic stress amplitude(HCF)has been used so far. Through the fatigue tests in wide fatigue region, CTOD was found to be a most suitable parameter in estimating fatigue damage. In case of LCF loading, the relationship between CTOD and the small crack growth rate corresponds fairly well to the relationship between the equivalent plastic strain and the small crack growth rate. On the other hand, the presence of the crack closure effect in HCF loading resulted in losing one-to-one correspondence found in LCF loading. This means, the crack growth rate should be estimated by using parameters DELTACTOD and DELTAKeff.

为了建立随机载荷下高可靠性的疲劳寿命预测方法，对雨流法（RFM）进行了重新解释，考虑了裂纹萌生和扩展的实际疲劳过程。在疲劳损伤计算中，目前常用的是循环塑性应变（LCF）或循环应力幅（HCF）。通过宽疲劳区的疲劳试验，发现CTOD是估算疲劳损伤最合适的参数。在低周疲劳载荷下，CTOD与小裂纹扩展速率之间的关系与等效塑性应变与小裂纹扩展速率之间的关系具有较好的对应关系。另一方面，在HCF加载中裂纹闭合效应的存在导致在LCF加载中发现的一对一对应关系的丢失。这意味着，裂纹扩展速率应该通过使用参数DELTACTOD和DELTAKeff来估计。

项目成果

Masahiro Miyake: "Growth Rate and Closure of Fatigue Cracks under High-Cycle Fatigue Random Loading" LOCALISED DAMAGE 96にて発表予定. (1996)

Masahiro Miyake：“高周疲劳随机载荷下疲劳裂纹的生长率和闭合”计划在 LOCALIZED DAMAGE 96 上发表。(1996)

Masahiro Miyake, Yoshihito Kuroshima and Shoji Harada: "Evaluation of Fatigue Crack Initiation Life under Random Loading" Proceedings of the 73rd JSME Fall Annual Meeting. Vol.I,No.95-10. 266-267 (1995)

Masahiro Miyake、Yoshihito Kuroshima 和 Shoji Harada：“随机载荷下疲劳裂纹萌生寿命的评估”第 73 届 JSME 秋季年会论文集。

Masahiro Miyake, Yoshihito Kuroshima, Shoji Harada and Masao Takahara: "Growth Rate and Closure of Fatigue Cracks under High-Cycle Fatigue Random Loading" LOCALISED DAMAGE96. (To appear).

Masahiro Miyake、Yoshihito Kuroshima、Shoji Harada 和 Masao Takahara：“高周疲劳随机载荷下疲劳裂纹的增长率和闭合”局部损伤 96。

原田 昭治他2名: "き裂発生・伝ぱに基づくランダム荷重下の疲労被害評価" 第72期全国大会 講演論文集. VoL.I. 235-237 (1994)

Shoji Harada 等 2 人：“基于裂纹萌生和扩展的随机载荷下的疲劳损伤评估”第 72 届全国会议演讲记录 VoL.I.235-237（1994 年）。

原田 昭治他2名: "き裂開閉口変位による変動荷重疲労損傷評価" 第72期通常総会 講演論文集. (発表予定).

原田庄司等2人：“裂纹张开/闭合位移引起的可变载荷的疲劳损伤评估”第72次普通股东大会记录（待提交）。