scholarly journals Introduction of Compressive Residual Stress by Means of Cavitation Peening into a Titanium Alloy Rod Used for Spinal Implants

2013 ◽  
Vol 04 (07) ◽  
pp. 23-28 ◽  
Author(s):  
Osamu Takakuwa ◽  
Amrinder S. Gill ◽  
Gokul Ramakrishnan ◽  
Seetha R. Mannava ◽  
Vijay K. Vasudevan ◽  
...  
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Compressive Residual Stress ◽  
Spinal Implants

Effect of the Type of Grinding Wheel on the Surface Characteristics of a Titanium Alloy with Internal Coolant Supply

2019 ◽  
Vol 825 ◽  
pp. 92-98
Author(s):  
Nakatsuka Nagatoshi ◽  
Sumito Toyokawa ◽  
Atsushi Kusakabe ◽  
Shinya Nakatsukasa ◽  
Hiroyuki Sasahara
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Silicon Carbide ◽  
Titanium Alloy ◽  
Aluminum Oxide ◽  
Compressive Residual Stress ◽  
Surface Characteristics ◽  
Grinding Wheel

The objective of this paper is to clarify the effect of grinding surface characteristics in the grinding of a titanium alloy with a coolant supply from the inner side of the grinding wheel. In this paper, we selected a white aluminum oxide (WA) vitrified bonded grinding wheel and a green silicon carbide (GC) vitrified bonded grinding wheel, and compared their grinding characteristics. As a result, in the case of the GC vitrified bonded grinding wheel, the surface roughness decreased by about 54% and the compressive residual stress increased by about 128%.

A Comparison of Fluids Used to Superabrasively Machine a Titanium Alloy

1991 ◽  
Author(s):  
James D. Campbell
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Specific Energy ◽  
Compressive Residual Stress ◽  
Water Soluble ◽  
Depth Of Cut ◽  
Grinding Wheel ◽  
Fluid Type ◽  
Power Flux ◽  
Screening Design

The objective of this paper was to compare the creep feed superabrasive machining of an alpha-beta structural titanium alloy, using a water-soluble and a straight oil grinding fluid, in terms of residual stress, specific energy, power flux and microstructure. The statistical effect of process variables on these criteria was investigated using a Taguchi screening design of experiment. Grinding wheel peripheral velocity, abrasive size and fluid type were the most important factors contributing to compressive residual stress. After the depth of cut, fluid type contributed the most variation to specific energy and power flux. Both fluids produced testpieces that were microstructurally sound, and were essentially stress free or had favorable compressive residual stress.

Peripheral milling-induced residual stress and its effect on tensile–tensile fatigue life of aeronautic titanium alloy Ti–6Al–4V

2019 ◽  
Vol 123 (1260) ◽  
pp. 212-229 ◽  
Author(s):  
Dong Yang ◽  
Xiao Xiao ◽  
Yulei Liu ◽  
Jing Sun
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Surface Energy ◽  
Compressive Residual Stress ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Stress Profile ◽  
Peripheral Milling ◽  
Residual Stress Profile

ABSTRACTThe special application environment puts forward the higher requirement of reliability of parts made from titanium alloy Ti–6Al–4V, which is closely related to the machining-induced residual stress. For the fact of the non-linear distribution of residual stress beneath the machined surface, distribution of peripheral milling-induced residual stress and its effect on fatigue performance of titanium alloy Ti–6Al–4V are still confusing. In the present study, residual stress profile induced by peripheral milling of Ti–6Al–4V is first studied. And then, energy criteria are proposed to characterise the whole state of the residual stress field. Finally, the effects of residual stress profile and surface energy on tensile–tensile fatigue performance of titanium alloy Ti–6Al–4V are discussed. The conclusions were drawn that the variation trend of surface residual stress (σr,Sur), maximum compressive residual stress (σC,ax), location (hr0) and response depth (hry) of residual stress profile with cutting parameters showed a similar pattern for both measure directions those parallel (σ1) and perpendicular (σ3) to the cutting direction. Cutting speed and feed rate have a main effect on surface residual stress, and the depth of cut has little effect on all the four key factors of residual stress profile. With the increase of cutting speed and feed rate, machining-induced surface energy tends to become larger. But increasing the depth of cut caused the strain energy stored in unit time to decrease. Furthermore, the effect of depth of cut on surface energy was weakened when the value of cutting depth becomes larger. Both the surface compressive residual stress and the maximum compressive residual stress are beneficial for prolonging the fatigue life, while large value of machining-induced surface energy leads to a decrease of fatigue life. Analysis of variance result shows that maximum residual compressive stress has a greater impact on fatigue life than other residual stress factors.

scholarly journals Effect of Residual Stress on S–N Curves and Fracture Morphology of Ti6Al4V Titanium Alloy after Laser Shock Peening without Protective Coating

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3799 ◽  
Author(s):  
Xinlei Pan ◽  
Xiang Li ◽  
Liucheng Zhou ◽  
Xiaotai Feng ◽  
Sihai Luo ◽  
...  
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Fatigue Life ◽  
Compressive Residual Stress ◽  
Fracture Morphology ◽  
High Amplitude ◽  
Laser Shock ◽  
Ti6al4v Titanium Alloy ◽  
Before And After ◽  
Shock Peening

In this paper, the effect of residual stress on the stress–life (S–N) curve and fracture morphology characteristics of Ti6Al4V titanium alloy after laser shock peening (LSP) without protective coating was experimentally investigated. The fatigue test and residual stress measurement were conducted on specimens before and after the LSP process. It was shown that LSP produced a high-amplitude compressive residual stress field on the surface of the specimen. After the LSP process, the fatigue life limit was increased by 16%, and the S–N curve shifted upward. Then, based on the theory of mean stress, the mechanism whereby the compressive residual stress improves the fatigue life of Ti6Al4V titanium alloy was analyzed. It indicated the improvement in fatigue life was because of the high-amplitude compressive residual stress on the surface and in depth induced by LSP to reduce the tensile stress produced by external loading. In addition, the scanning electron microscope (SEM) pattern of fatigue fracture demonstrated distinct differences in the fracture morphology before and after LSP. After LSP, the crack initiation sites of the samples moved to the subsurface where it was difficult for fatigue cracks initiating here. Moreover, after the LSP process, there were high density of fatigue striations and many secondary cracks on the fracture of the treated specimen.

Experimental Study on Prestressed Cutting of Alloy Ring Parts

2016 ◽  
Vol 836-837 ◽  
pp. 71-76
Author(s):  
Rui Tao Peng ◽  
Yang Ge Li ◽  
Xin Zi Tang ◽  
Zhuan Zhou
Keyword(s):  
Residual Stress ◽  
Titanium Alloy ◽  
Stress Distribution ◽  
Cutting Force ◽  
Surface Integrity ◽  
Compressive Residual Stress ◽  
Machining Process ◽  
Residual Tensile Stress ◽  
Machined Surface ◽  
Cutting Method

In order to solve the poor cutting performance for the titanium alloy and the serious residual tensile stress distribution on the machined surface in cutting titanium alloy, the utilization of prestressed cutting method is proposed to actively control the residual stress distribution status on the machined surface in machining process. Titanium alloy ring parts were pre-stretched at different condition by a lathe-specific pretension device respectively. By the cutting experimental, the cutting force ,chip formation and surface integrity indexes are compared and studied. The results show that in suitable compressive residual stress on machined surface are achieved by utilizing the prestressed cutting method ,meanwhile procedures of residual stress adjustment after machining could be omitted. Furthermore, the magnitude of compressive residual stress could be actively controlled by adjusting the magnitude of prestressed force in certain extent. And uniform saw-tooth chip are generated in prestressed cutting, meanwhile there’s no significant increment of cutting force. Prestressed cutting method could generate good surface integrity.

Monitoring of mechanical properties of prestressed glass fiber epoxy composites over 12 months after fabrication

2021 ◽  
pp. 002199832110047
Author(s):  
Mahmoud Mohamed ◽  
Siddhartha Brahma ◽  
Haibin Ning ◽  
Selvum Pillay
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Flexural Strength ◽  
Compressive Residual Stress ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Epoxy Composites ◽  
Flexural Properties ◽  
Initial Increase ◽  
Fiber Volume

Fiber prestressing during matrix curing can significantly improve the mechanical properties of fiber-reinforced polymer composites. One primary reason behind this improvement is the generated compressive residual stress within the cured matrix, which impedes cracks initiation and propagation. However, the prestressing force might diminish progressively with time due to the creep of the compressed matrix and the relaxation of the tensioned fiber. As a result, the initial compressive residual stress and the acquired improvement in mechanical properties are prone to decline over time. Therefore, it is necessary to evaluate the mechanical properties of the prestressed composites as time proceeds. This study monitors the change in the tensile and flexural properties of unidirectional prestressed glass fiber reinforced epoxy composites over a period of 12 months after manufacturing. The composites were prepared using three different fiber volume fractions 25%, 30%, and 40%. The results of mechanical testing showed that the prestressed composites acquired an initial increase up to 29% in the tensile properties and up to 32% in the flexural properties compared to the non-prestressed counterparts. Throughout the 12 months of study, the initial increase in both tensile and flexural strength showed a progressive reduction. The loss ratio of the initial increase was observed to be inversely proportional to the fiber volume fraction. For the prestressed composites fabricated with 25%, 30%, and 40% fiber volume fraction, the initial increase in tensile and flexural strength dropped by 29%, 25%, and 17%, respectively and by 34%, 26%, and 21%, respectively at the end of the study. Approximately 50% of the total loss took place over the first month after the manufacture, while after the sixth month, the reduction in mechanical properties became insignificant. Tensile modulus started to show a very slight reduction after the fourth/sixth month, while the flexural modulus reduction was observed from the beginning. Although the prestressed composites displayed time-dependent losses, their long-term mechanical properties still outperformed the non-prestressed counterparts.

scholarly journals Influence of Preaging Temperature on the Indentation Strength of 3Y-TZP Aged in Ambient Atmosphere

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2767
Author(s):  
Ki-Won Jeong ◽  
Jung-Suk Han ◽  
Gi-Uk Yang ◽  
Dae-Joon Kim
Keyword(s):  
Residual Stress ◽  
Phase Transformation ◽  
Low Temperature ◽  
Compressive Residual Stress ◽  
Yttria Stabilized Zirconia ◽  
Ambient Atmosphere ◽  
Aged Specimen ◽  
Stabilized Zirconia ◽  
M Phase ◽  
The Relationship

Yttria-stabilized zirconia (3Y-TZP) containing 0.25% Al2O3, which is resistant to low temperature degradation (LTD), was aged for 10 h at 130–220 °C in air. The aged specimens were subsequently indented at loads ranging from 9.8 to 490 N using a Vickers indenter. The influence of preaging temperature on the biaxial strength of the specimens was investigated to elucidate the relationship between the extent of LTD and the strength of zirconia restorations that underwent LTD. The indented strength of the specimens increased as the preaging temperature was increased higher than 160 °C, which was accompanied by extensive t-ZrO2 (t) to m-ZrO2 (m) and c-ZrO2 (c) to r-ZrO2 (r) phase transformations. The influence of preaging temperature on the indented strength was rationalized by the residual stresses raised by the t→m transformation and the reversal of tensile residual stress on the aged specimen surface due to the indentation. The results suggested that the longevity of restorations would not be deteriorated if the aged restorations retain compressive residual stress on the surface, which corresponds to the extent of t→m phase transformation less than 52% in ambient environment.

Sign in / Sign up

Export Citation Format

Share Document