针对焊接锚垫板齿板锚固区配筋,提出了一种锚固区新型拉压杆模型。首先对齿板锚固区6种典型效应、主应力迹线以及力流平衡关系进行分析并建立新型拉压杆模型,其次通过美国国家公路与运输官员协会(American Association of State Highway...针对焊接锚垫板齿板锚固区配筋,提出了一种锚固区新型拉压杆模型。首先对齿板锚固区6种典型效应、主应力迹线以及力流平衡关系进行分析并建立新型拉压杆模型,其次通过美国国家公路与运输官员协会(American Association of State Highway and Transportation Officials,AASHTO)Load-and-resistance Factor Design Bridge Design Specifications、Building Code Requirements for Structural Concrete and Commentary(ACI 318-19)、《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG 3362—2018)和欧洲设计建议Practical Design of Structural Concrete进行拉压杆模型参数定量化设计,根据拉压杆几何关系推导出焊接锚垫板齿板锚固区劈裂力计算式,利用有限元分析,拟合出焊接锚垫板下齿板锚固区劈裂力合力重心计算式。最后通过算例分析,按本文建议的拉压杆方法进行焊接锚垫板齿板锚固区结构配筋设计,能较好地控制锚下典型效应问题,相比《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG 3362—2018)给出的设计方法,拉压杆模型法能较好地反映结构传力机制且具备可行性和可应用性,可为焊接锚垫板齿板锚固区配筋设计提供参考。展开更多
In die casting,the real-time measurement of the stress of the tie-bar helps ensure product quality and protect the machine itself.However,the traditional magnetic-attached strain gauge is installed in the mold and pro...In die casting,the real-time measurement of the stress of the tie-bar helps ensure product quality and protect the machine itself.However,the traditional magnetic-attached strain gauge is installed in the mold and product operating area,which hinders the loading and unloading of the mold and the collection of die castings.In this paper,a method for real-time measurement of stress using ultrasonic technology is proposed.The stress variation of the tie-bar is analyzed,and a mathematical model between ultrasonic signal and stress based on acoustoelastic theory is established.Verification experiments show that the proposed method agrees with the strain gauge,and the maximum of the difference square is only 1.5678(MPa)2.Furthermore,single-factor experiments are conducted.A higher ultrasonic frequency produces a better measurement accuracy,and the mean of difference squares at 2.5 and 5 MHz are 2.3234 and 0.6733(MPa)_(2),respectively.Measurement accuracy is insensitive to probe location and tonnage of the die-casting machine.Moreover,the ultrasonic measurement method can be used to monitor clamping health status and inspect the dynamic pulling force of the tie-bar.This approach has the advantages of high precision,high repeatability,easy installation,and noninterference,which helps guide the production in die casting.展开更多
文摘针对焊接锚垫板齿板锚固区配筋,提出了一种锚固区新型拉压杆模型。首先对齿板锚固区6种典型效应、主应力迹线以及力流平衡关系进行分析并建立新型拉压杆模型,其次通过美国国家公路与运输官员协会(American Association of State Highway and Transportation Officials,AASHTO)Load-and-resistance Factor Design Bridge Design Specifications、Building Code Requirements for Structural Concrete and Commentary(ACI 318-19)、《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG 3362—2018)和欧洲设计建议Practical Design of Structural Concrete进行拉压杆模型参数定量化设计,根据拉压杆几何关系推导出焊接锚垫板齿板锚固区劈裂力计算式,利用有限元分析,拟合出焊接锚垫板下齿板锚固区劈裂力合力重心计算式。最后通过算例分析,按本文建议的拉压杆方法进行焊接锚垫板齿板锚固区结构配筋设计,能较好地控制锚下典型效应问题,相比《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG 3362—2018)给出的设计方法,拉压杆模型法能较好地反映结构传力机制且具备可行性和可应用性,可为焊接锚垫板齿板锚固区配筋设计提供参考。
基金The authors acknowledge the financial support of the Key Project of Science and Technology Innovation 2025 of Ningbo City,China(Grant No.2020Z018)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province,China(Grant No.2022C01069)+1 种基金the National Natural Science Foundation of China(Grant No.51875519)the Project of Innovation Enterprises Union of Ningbo City,China(Grant No.2021H002).
文摘In die casting,the real-time measurement of the stress of the tie-bar helps ensure product quality and protect the machine itself.However,the traditional magnetic-attached strain gauge is installed in the mold and product operating area,which hinders the loading and unloading of the mold and the collection of die castings.In this paper,a method for real-time measurement of stress using ultrasonic technology is proposed.The stress variation of the tie-bar is analyzed,and a mathematical model between ultrasonic signal and stress based on acoustoelastic theory is established.Verification experiments show that the proposed method agrees with the strain gauge,and the maximum of the difference square is only 1.5678(MPa)2.Furthermore,single-factor experiments are conducted.A higher ultrasonic frequency produces a better measurement accuracy,and the mean of difference squares at 2.5 and 5 MHz are 2.3234 and 0.6733(MPa)_(2),respectively.Measurement accuracy is insensitive to probe location and tonnage of the die-casting machine.Moreover,the ultrasonic measurement method can be used to monitor clamping health status and inspect the dynamic pulling force of the tie-bar.This approach has the advantages of high precision,high repeatability,easy installation,and noninterference,which helps guide the production in die casting.
