Ultrasonic Drilling and Coring for Planetary Astrobiological Applications

行星探索是21世纪最令人兴奋的科学努力之一的关键，那就是寻找地球外的生命。表面漫游车在行星探测中的主要作用是外部生物勘探。自主漫游车是寻找以前或现存的益生生物或生物物种证据的关键。为此，需要开发可靠和有效的仪器，能够现场采样和进行天体生物学分析。目前，钻探需要很大的轴向力，需要支撑扭矩和高功率。这限制了常规钻机/取心器的应用，使其只能用于非常稳定和具有坚固锚固的大型平台。常规钻机耗能大，易卡钻、断钻、钝化，难以用于非垂直作业，钻屑堆积阻碍了钻井过程。因此，这项研究的目的是为行星天体生物应用建立、设计、制造和测试超声波钻头/取样器。超声波钻孔的基本原理是在较低的超声波频率范围内振动刀具，以相对较高的速度产生微小的轴向运动。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碎，从而允许使用适度的预紧力进行钻孔或切割。这项拟议的研究将开发一种新的超声钻井/取心方法，采用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，并消除旋转钻井的需要。该设计将依赖于开发经过验证的岩石超声钻探有限元模型，以便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。工业合作伙伴EADS Astrium为该项目带来了必要的专业知识和支持，在高度专业化的空间科学领域拥有世界知名的专业知识，并获得了几项空间行业第一。EADS Astrium拥有一些航天行业设备最齐全、最先进的设计、制造和测试设施。设计小型、低功率、低预载的超声波钻孔机/取样器以切割岩石所面临的挑战同样适用于焊接工艺和食品切割应用的新型超声波设备的设计。目前，超声波焊接机是大型组件，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)的能力已变得至关重要。超声波切割食品已被证明是一种有效的技术，在提高切割速度的同时，大幅减少了产品浪费，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，超声波钻孔机/取样器的成功设计将为新一代低功率超声波焊接设备和刀具的设计提供机会，使其适用于更广泛的材料。第二个工业合作伙伴布兰森超声波公司的英国分公司是超声波焊接领域的市场领先者，由于与食品行业的密切关系，该公司最近开发了几项用于食品超声波切割的新创新。因此，布兰森在英国处于一个独特的地位，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.