Pub Date : 2022-01-21DOI: 10.22541/au.164277431.14120940/v1
D. Hattingh, Sheldyn Botha, D. Bernard, M. James, A. Plessis
Titanium is a versatile biocompatible metal that is desirable in additively manufactured medical implant devices. However, additively manufactured parts have particular microstructures, porosity, residual stress and surface conditions which can have a strong impact on fatigue performance. Implants have an added complexity from the saline operating environment and the associated impact on the safe design life. Equally, direct energy deposition induces a complex thermal history which, if not carefully controlled, can significantly alter the mechanical/material properties of the component. This study investigates the decrease in fatigue life, in an in-vitro body fluid simulation using Ringer’s solution, observed in Ti-6Al-4V specimens extracted from coupons manufactured by directed energy deposition. An interrupted deposition strategy was employed to control build regularity, which appeared to influence certain mechanical properties, including corrosion fatigue life. An ≈50% decrease in fatigue life was observed in Ringer’s solution at 6 Hz loading frequency, clearly important in designing implants.
{"title":"Corrosion-Fatigue of Ti-6Al-4V Coupons Manufactured by Directed Energy Deposition","authors":"D. Hattingh, Sheldyn Botha, D. Bernard, M. James, A. Plessis","doi":"10.22541/au.164277431.14120940/v1","DOIUrl":"https://doi.org/10.22541/au.164277431.14120940/v1","url":null,"abstract":"Titanium is a versatile biocompatible metal that is desirable in\u0000additively manufactured medical implant devices. However, additively\u0000manufactured parts have particular microstructures, porosity, residual\u0000stress and surface conditions which can have a strong impact on fatigue\u0000performance. Implants have an added complexity from the saline operating\u0000environment and the associated impact on the safe design life. Equally,\u0000direct energy deposition induces a complex thermal history which, if not\u0000carefully controlled, can significantly alter the mechanical/material\u0000properties of the component. This study investigates the decrease in\u0000fatigue life, in an in-vitro body fluid simulation using Ringer’s\u0000solution, observed in Ti-6Al-4V specimens extracted from coupons\u0000manufactured by directed energy deposition. An interrupted deposition\u0000strategy was employed to control build regularity, which appeared to\u0000influence certain mechanical properties, including corrosion fatigue\u0000life. An ≈50% decrease in fatigue life was observed in Ringer’s\u0000solution at 6 Hz loading frequency, clearly important in designing\u0000implants.","PeriodicalId":127256,"journal":{"name":"Fatigue & Fracture of Engineering Materials & Structures","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122151395","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}
Pub Date : 2021-12-01DOI: 10.22541/au.163832788.81209893/v1
Jingwu Bu, Huiying Xu, Xinyu Wu, Xudong Chen, Bo Xu
In order to study the fracture properties of dam concrete under post-peak cyclic loading, wedge splitting tests with three loading rates (0.001 mm/s, 0.01 mm/s, 0.1 mm/s) were performed on notched cubic dam concrete specimens. Meanwhile, the acoustic emission (AE) and digital image correlation (DIC) technologies were used to record the crack propagation process of specimens. Test results show that the fracture of dam concrete has a significant rate effect: with the loading rate increases, the peak load increases, the slope of the post-peak P-CMOD curve gradually decreases and the stiffness degradation of dam concrete becomes more serious. The cumulative AE count shows a step increasing trend and has a Kaiser effect. The Kaiser effect decreases with the post-peak cyclic loading procedure, and with the loading rate increases, the Kaiser effect increases. With the increasing of loading rate, AE energy fluctuates violently and b value fluctuates frequently, indicating the damage of dam concrete becomes more serious. As the loading procedure, the damage of the specimen accumulates gradually, and the strain recovery rate decreases gradually. With the loading rate increases, the strain recovery rate decreases and the permanent crack increases. Based on the fictitious crack model, the effective crack length shows a gradual and steady rising trend. As the loading rate increases, the growth rate of the effective crack length becomes large.
{"title":"Experimental study on fracture properties of dam concrete under post-peak cyclic loading based on DIC and acoustic emission techniques","authors":"Jingwu Bu, Huiying Xu, Xinyu Wu, Xudong Chen, Bo Xu","doi":"10.22541/au.163832788.81209893/v1","DOIUrl":"https://doi.org/10.22541/au.163832788.81209893/v1","url":null,"abstract":"In order to study the fracture properties of dam concrete under\u0000post-peak cyclic loading, wedge splitting tests with three loading rates\u0000(0.001 mm/s, 0.01 mm/s, 0.1 mm/s) were performed on notched cubic dam\u0000concrete specimens. Meanwhile, the acoustic emission (AE) and digital\u0000image correlation (DIC) technologies were used to record the crack\u0000propagation process of specimens. Test results show that the fracture of\u0000dam concrete has a significant rate effect: with the loading rate\u0000increases, the peak load increases, the slope of the post-peak P-CMOD\u0000curve gradually decreases and the stiffness degradation of dam concrete\u0000becomes more serious. The cumulative AE count shows a step increasing\u0000trend and has a Kaiser effect. The Kaiser effect decreases with the\u0000post-peak cyclic loading procedure, and with the loading rate increases,\u0000the Kaiser effect increases. With the increasing of loading rate, AE\u0000energy fluctuates violently and b value fluctuates frequently,\u0000indicating the damage of dam concrete becomes more serious. As the\u0000loading procedure, the damage of the specimen accumulates gradually, and\u0000the strain recovery rate decreases gradually. With the loading rate\u0000increases, the strain recovery rate decreases and the permanent crack\u0000increases. Based on the fictitious crack model, the effective crack\u0000length shows a gradual and steady rising trend. As the loading rate\u0000increases, the growth rate of the effective crack length becomes large.","PeriodicalId":127256,"journal":{"name":"Fatigue & Fracture of Engineering Materials & Structures","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115313369","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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