尼丁醇的旋转曲疲劳到十亿个周期
J D Weaver1, G M Sena1, K I Aycock1
1U.S. Food and Drug Administration (FDA), Silver Spring, MD, USA.
概括
尼丁醇疲劳行为被研究到10^9周期. 在108次循环之后,疲劳骨折变得很常见,这表明尼醇植入物中超高循环疲劳的双失败模型.
科学领域:
- 生物材料科学 生物材料科学
- 机械工程 机械工程
- 材料科学 材料科学 材料科学
背景情况:
- 尼丁醇植入物需要超过108个周期的耐用性.
- 尼醇中超高循环疲劳机制尚不清楚.
- 除了10^8周期之外,关于尼提诺疲劳行为的文献很少.
研究的目的:
- 在超高循环状态下 (超过108个循环) 调查尼丁醇疲劳行为.
- 描述尼提诺的疲劳寿命,了解故障机制.
- 为改善尼醇植入物的耐用性提供见解.
主要方法:
- 医学级尼醇线的旋转曲疲劳测试.
- 详细的材料表征.
- 有限元分析和计算模拟.
- 对疲劳寿命数据的后期分析.
主要成果:
- 在10^5周期以下,循环相转换与疲劳失败相关.
- 在10^5和10^8周期之间,骨折很少发生.
- 超过10^8周期后,疲劳骨折变得很常见,受负载水平和非金属含的影响.
- 这项研究是第一个将尼提诺疲劳记录到10^9周期的研究.
结论:
- 两个失效模型可能比Coffin-Manson方程更适合尼丁醇疲劳寿命超过10^8周期.
- 了解超高循环疲劳对于设计耐用的尼醇医疗器械至关重要.
- 这些发现将有助于工程师提高未来尼醇植入物的寿命.
相关概念视频
Fatigue
213
Fatigue occurs when materials rupture under repeated or fluctuating loads, even at stress levels far below their static breaking strength. It typically results in brittle failure, even for ductile materials. It is a critical consideration in designing machines and structural components subjected to repetitive or varying loads. The nature of these loadings can range from fluctuating loads like unbalanced pump impellers causing vibrations to repeatedly bending a thin steel rod wire back and forth...
213
Deformation in a Circular Shaft
391
One of the distinctive characteristics of circular shafts is their ability to maintain their cross-sectional integrity under torsion. In other words, each cross-section continues to exist as a flat, unaltered entity, simply rotating like a solid, rigid slab. To understand the distribution of shearing stress within such a shaft, consider a cylindrical section inside this circular shaft. This section has a length of L and a radius of R, with one end fixed. The radius of the cylindrical section is...
391
Stress Concentrations in Circular Shafts
207
Consider the elastic torsion formula, which applies to a circular shaft with a consistent cross-section. This formula assumes that the shaft's ends are loaded with rigid plates firmly attached. However, in many cases, torques are applied to the shaft through mechanisms like flange couplings or gears, which are connected by keys inserted into keyways. This application method modifies the stress distribution near the point of torque application, causing it to deviate from the distributions...
207
Plastic Deformation in Circular Shafts
210
When materials are subjected to forces that surpass their yield strength, they undergo a process known as plastic deformation. This results in a permanent alteration or strain in their structure. This concept can be specifically applied to circular shafts, where the deformation leads to a change in its shape. The precise evaluation of this plastic deformation requires understanding the stress distribution within the circular shaft, which is achieved by calculating the maximum shearing stress in...
210
Bending of Material: Problem Solving
218
In this lesson, determine the ratio of the maximum bending moments applied to two metal pipes, given that both pipes can withstand a maximum stress of 100 MPa. Both pipes have an outer radius of 1.8 cm. Pipe A has an inner radius of 1.5 cm, and Pipe B has an inner radius of 1 cm. The ratio of the maximum bending moment applied to two metallic pipes, each with a different inner and outer radius, is determined by considering their dimensions. The inner radius of the first pipe is 1.5 cm, and for...
218
Circular Shaft - Stresses in Linear Range
325
Consider a scenario where a circular shaft is subject to torque that remains within the boundaries of Hooke's Law, avoiding any permanent deformation. So, the formula for shearing strain is revisited. This formula is multiplied by the modulus of rigidity, and then Hooke's Law for the shearing stress and strain is applied. As a result, the equation for shearing stress in a shaft can be derived.
325


