Ultrasonic Drilling and Coring for Planetary Astrobiological Applications

行星探索是21世纪最激动人心的科学努力之一的关键；寻找地球外的生命地表探测车在行星探测中的主要作用是外太空生物勘探。自主探测车是寻找以前或现存的益生元或生物物种证据的关键。为此目的，需要开发可靠和有效的仪器，可以采样和进行现场天体生物学分析。目前，钻井需要较大的轴向力、保持力矩和大功率。这限制了传统的司钻/井盖应用于非常稳定的大型平台。常规钻具耗能大，钻头容易卡钻、断裂和磨铣，难以用于非垂直作业，钻井过程也受到钻井碎屑堆积的阻碍。因此，本研究的目的是建模、设计、建造和测试用于行星天体生物学应用的超声波钻/盖。超声波钻孔的基本原理是在低超声频率范围内振荡切削刀具，以相对较高的速度产生小的轴向运动。工具对岩石表面的冲击会在晶体和矿物结构中产生微裂缝，导致表面被侵蚀和破坏，从而允许在适度的预载荷下实现钻井或切割。该研究将开发一种新的超声钻井/取心方法，通过将弯曲超声换能器作为设备的驱动端，使钻头小型化而不损失振动幅度，并且不再需要旋转钻井。为了比较不同的钻头设计，并预测钻头和工件的振动和温度响应，该设计将依赖于在岩石中超声波钻井的有效有限元模型的发展。工业合作伙伴EADS Astrium为该项目提供了必要的专业知识和支持，该公司在高度专业化的空间科学领域拥有世界知名的专业知识，并拥有多项航天工业第一。EADS Astrium拥有航天工业中最先进的设计、制造和测试设施。设计一种小型、低功率、低预紧力的超声波钻/盖来切割岩石的挑战，同样适用于设计用于焊接过程和食品切割应用的新型超声波设备。目前，超声波焊机是大型组件，但随着电子和医疗设备的小型化，连接不同材料（如金属、陶瓷和玻璃）的能力变得至关重要。食品的超声波切割已被证明是一种有效的技术，在提高切割速度的情况下，大大减少了产品浪费，提高了切割质量。然而，超声波切割机往往是大型工具，只能切割有限范围的食品。对于这两种应用，超声钻/盖的成功设计将为设计新一代低功率超声焊接设备和切割机提供机会，这些设备和切割机适用于更广泛的材料。布兰森超声波公司的英国分部是第二个工业合作伙伴，是超声波焊接的市场领导者，由于与食品行业的密切关系，最近开发了几种超声波切割食品的新创新。因此，布兰森在英国处于独特的地位，可以在这个研究项目中进行合作。

Planetary exploration is the key to one of the most exciting scientific endeavours of the 21st century; the search for life outside planet Earth. A primary role for surface rovers in planetary exploration is exobiological prospecting. Autonomous rovers are the key to finding evidence of former or extant prebiotic or biotic species. For this purpose, reliable and effective instruments that can sample and conduct in-situ astrobiology analysis need to be developed. Currently, drilling requires large axial forces and holding toques and high power. This limits conventional driller/corer applications to very stable and large platforms with solid anchoring. Conventional drillers consume a lot of energy, are subject to drill bit jamming, breaking and dulling, are difficult to use for non-vertical operations and the drilling process is hampered by the accumulation of drilling debris. The aim of this study is therefore to model, design, build and test an ultrasonic driller/corer for planetary astrobiological applications The fundamental principle of ultrasonic drilling is to oscillate a cutting tool in the low ultrasonic frequency range, to produce a small axial motion at a relatively high velocity. The impact of the tool against the surface of the rock produces micro-fractures in the crystal and mineral structure causing the surface to be eroded and broken, thus allowing drilling or cutting to be achieved using a modest preload. The proposed research will develop a novel approach to ultrasonic drilling/coring by adapting flextensional ultrasonic transducers as the driving end of the device, allowing the drill to be miniaturised without loss of vibration amplitude, and to remove the need for rotational drilling. The design will rely on the development of validated finite element models of ultrasonic drilling in rock, in order both to compare different drill designs and to predict the vibration and temperature responses of the drill and workpiece. Bringing essential expertise and support to this project, the industrial partner, EADS Astrium, has world-renowned expertise in the highly specialised field of space science, with several space industry firsts to its credit. EADS Astrium owns some of the best-appointed and most advanced design, manufacture and test facilities in the space industry. The challenges in designing a small, low power, low preload ultrasonic driller/corer to cut through rock, equally apply to the design of novel ultrasonic devices for welding processes and food cutting applications. Currently, ultrasonic welders are large assemblies but, with the move towards miniaturisation of electronic and medical devices, the capability of joining dissimilar materials such as metals, ceramics and glass, has become of paramount importance. Ultrasonic cutting of food products has proved to be an effective technology, achieving substantial reductions in product waste and improved cut quality at increased cutting speed. However, ultrasonic cutters tend to be large tools capable of cutting only a limited range of food products. For both applications, successful design of the ultrasonic driller/corer will provide opportunities for the design of a new generation of low power ultrasonic welding devices and cutters, adaptable to a much wider variety of materials. The UK division of Branson Ultrasonics, the second industrial partner, is the market leader in ultrasonic welding and, as a result of close relationships with the food industry, has recently developed several new innovations for ultrasonic cutting of food products. Branson are therefore in a unique position in the UK to collaborate in this research project.