美国社会学论文代写 人类的手

人类的手可以执行多种不同的任务。根据关节的不同，手的各个成员可以在不同的运动范围内进行一个或两个维度的旋转。例如，手腕可以旋转屈伸和尺侧屈曲。单个关节旋转的组合创造了可以执行圆柱形和球形任务的运动;抓取、尖捏、掌捏、钩、咬等。设计假肢的目的是复制对截肢者最有用的某些动作。假肢能够做出的具体动作需要根据使用者的复杂性、应用应力、实用性和易用性来考虑。在这个应用程序中最有用的动作被定义为被用户高度使用并能最好地提高用户生活质量的动作。当设计一个新的假体时，考虑材料和结构是很重要的。产品应该美观，防水，轻便，但非常耐用和坚固。所有这些设计标准都依赖于为设计所选择的材料，因此了解每一种材料的具体特性尤为重要。抗压、抗拉、抗剪、抗扭以及减震等性能是模拟真实人体肢体运动的重要性能。在设计舒适持久的假肢时，抗疲劳、蠕变和耐腐蚀是重要的性能。最后，假肢设计的生物相容性对截肢者很重要。假肢的生物相容性指的是材料与截肢者皮肤和活组织表面的相容性。与活组织不相容的材料会在截肢区域造成不适和压力。

美国社会学论文代写 人类的手

The human hand can perform a multitude of distinct tasks. Depending on the joint, members of the hand can rotate in one or two dimensions with varying ranges of motion . For example, the wrist can rotate in flexion and extension and ulnar flexion and. The combination of individual joint rotations creates movements that can perform tasks such as cylindrical and spherical; grasping, tip and palmar pinching, hook and snapping etc . The goal when designing a prosthetic is to replicate certain movements that are most useful to an amputee. The specific movements which the prosthetic should be capable of will need to be considered based on complexity, stresses applied, usefulness, and ease of use for the user. Movements that are most useful in this application are defined as movements that are highly used by the user that best improve the user’s quality of life. When designing a new prosthetic, it is important to consider the materials and the structure. The product should be aesthetically pleasing, waterproof and lightweight, yet very durable and strong. All these design criteria rely on the materials chosen for the design, thus it is especially important to understand the specific properties of each material used. Properties such as compressive, tensile, shear and torsional strength as well as shock absorption are important properties to mimic a real human limb’s movement . Fatigue resistance, creep and resistance to corrosion are important properties to possess when designing a comfortable and lasting prosthetic . Lastly, it is important for a prosthetic design to be biocompatible with the amputee. A prosthetic’s biocompatibility speaks to the materials agreeability with the surface of the amputee’s skin and living tissue . A material that is not biocompatible with living tissue will cause discomfort and stress in the amputated area .

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