Mechanical Engineering Commons^™

Simultaneous Actuation And Sensing Of Electrostatic Mems, Jacob E. Song

Theses and Dissertations

Micro-Electro-Mechanical Systems (MEMS) are devices that play important roles of sensing and actuation in many different industries including automation, electronics, medical, communications, and defense. In order to make full use of these devices, it is important to understand the peripherals that enable these devices. Simultaneous actuation and control of MEMS devices is an important area of research as it enables feedback control of these device and allows devices to maintain performance as devices depreciate over their lifetime. The aim of this thesis is to perform a design space analysis on an electrostatic MEMS simultaneous actuation and sensing circuit that is ...

Preparation And Wear Properties Of High-Vanadium Alloy Composite Layer, Fangfang Wang, Liujie Xu, Shizhong Wei, Xi Wang, Chong Chen, Yucheng Zhou

Friction

A high-vanadium alloy composite layer was prepared on the surface of a carbon steel using cast composite technology, and the wear properties of the composite layer were investigated. The results showed that the microstructure of the composite layer was composed of primary vanadium carbides (VC), flake martensite, residual austenite, and fine VC. The hardness of the cast alloy layer was 63 HRC. The abrasive wear resistance and impact wear resistance were increased by 60% and 26%, respectively, compared with those of high-chromium cast iron. The excellent wear resistance of the cast alloy layer is attributed to the high-hardness primary vanadium ...

An Advanced Efficient Model For Adhesive Wear In Elastic–Plastic Spherical Contact, Haibo Zhang, Izhak Etsion

Friction

A finite element (FE) model combining submodel technique is presented for the adhesive wear in elastic–plastic spherical contact. It consists of a global model, showing the potential location of fracture under combined normal and tangential loading, and a refined mesh submodel covering only the region near the potential fracture. This allows to describe the morphology of wear particle more accurately than that in a previously developed model by the authors. A range of normal loading is studied to show its effect on the shape and volume of wear particles. Two main regimes of mild and severe wear (along with ...

Unlocking The Secrets Behind Liquid Superlubricity: A State-Of-The-Art Review On Phenomena And Mechanisms, Tianyi Han, Shuowen Zhang, Chenhui Zhang

Friction

Superlubricity, the state of ultralow friction between two sliding surfaces, has become a frontier subject in tribology. Here, a state-of-the-art review of the phenomena and mechanisms of liquid superlubricity are presented based on our ten-year research, to unlock the secrets behind liquid superlubricity, a major approach to achieve superlubricity. An overview of the discovery of liquid superlubricity materials is presented from five different categories, including water and acid-based solutions, hydrated materials, ionic liquids (ILs), two-dimensional (2D) materials as lubricant additives, and oil-based lubricants, to show the hydrodynamic and hydration contributions to liquid superlubricity. The review also discusses four methods to ...

Bio-Inspired Smart Surface To Achieve Controllable Locomotion Through Adjustable Anisotropic Friction, Zhongying Ji, Shiyu Qin, Shuanhong Ma, Xin Jia, Xiaolong Wang, Feng Zhou

Friction

Anisotropic friction generated by microstructured surfaces is crucial for performing functions such as directional locomotion and adhesion in biological systems. Hence, an epoxy-based shape memory polymer (SMP) incorporating Fe₃O₄ nanoparticles is used in this study to create a smart surface with oriented structures to mimic anisotropic friction and exploit human-developed controllable locomotion systems. Applying the specific properties of the epoxy-based SMP, fast switching friction can be achieved by adjusting the topography and stiffness of the microstructures on the surface. In addition, the photothermogenesis effect of Fe₃O₄ nanoparticles induces changes in the asymmetric topography and ...

Robust Scalable Reversible Strong Adhesion By Gecko-Inspired Composite Design, Xiaosong Li, Pengpeng Bai, Xinxin Li, Lvzhou Li, Yuanzhe Li, Hongyu Lu, Liran Ma, Yonggang Meng, Yu Tian

Friction

Bio-inspired reversible adhesion has significant potential in many fields requiring flexible grasping and manipulation, such as precision manufacturing, flexible electronics, and intelligent robotics. Despite extensive efforts for adhesive synthesis with a high adhesion strength at the interface, an effective strategy to actively tune the adhesion capacity between a strong attachment and an easy detachment spanning a wide range of scales has been lagged. Herein, we report a novel soft-hard-soft sandwiched composite design to achieve a stable, repeatable, and reversible strong adhesion with an easily scalable performance for a large area ranging from ~1.5 to 150 cm² and a ...

Role Of Capillary Adhesion In The Friction Peak During The Tacky Transition, Tianyan Gao, Jiaxin Ye, Kaisen Zhang, Xiaojun Liu, Yan Zhang, Kun Liu

Friction

The friction peak that occurs in tire–road sliding when the contact changes from wet to dry was previously attributed to capillary cohesion, van der Waals attraction, and surface roughness, but the detailed mechanisms have yet to be revealed. In this study, friction and static contact experiments were conducted using a custom-built in situ optical microtribometer, which allowed us to investigate the evolution of the friction, normal load, and contact area between a polydimethylsiloxane (PDMS) film and a silicon nitride ball during water volatilization. The friction coefficient increased by 100%, and the normal force dropped by 30% relative to those ...

Optimization Of Several Surface Treatment Processes For Alleviating Fretting Damage Of A Locking Pin, Jifan He, Zhenbing Cai, Yanping Ren, Jinfang Peng, Jianhua Liu, Minhao Zhu

Friction

The operational safety and reliability of a variable gauge train are affected by the anti-fretting wear performance of the locking mechanism. The main purpose of this study is to optimize the surface treatment process for a locking pin material under actual service conditions to alleviate fretting damage. Based on the two basic principles of surface strengthening and friction reduction, a substrate (AISI 4135 steel) surface was treated by laser quenching (LQ), plasma nitriding (PN), and bonded MoS₂ coating. Systematic fretting wear tests were conducted, and the wear behavior and damage mechanism of various treated surfaces were comprehensively investigated. The ...

Laser Pattern-Induced Unidirectional Lubricant Flow For Lubrication Track Replenishment, Chenglong Liu, Feng Guo, Patrick Wong, Xinming Li

Friction

Effective oil replenishment to the lubrication track of a running bearing is crucial to its sustainable operation. Reliable practical solutions are rare despite numerous theoretical studies were conducted in the last few decades. This paper proposes the use of surface effect, wettability gradient, to achieve the goal. This method is simple and can be nicely implemented using femtosecond laser ablation. A periodic comb-tooth-shaped pattern with anisotropic wetting capability is devised and its effect on the anisotropic spreading behaviour of an oil droplet is studied. Results show that the comb-tooth-shaped pattern enables the rearrangement of oil distribution, thereby escalating oil replenishment ...

Tribological Performance And Scuffing Behaviors Of Several Automobile Piston Rings Mating With Chrome-Plated Cylinder Liner, Zeyu Ma, Ruoxuan Huang, Xiaoshuai Yuan, Yan Shen, Jiujun Xu

Friction

The friction and wear properties, as well as the scuffing resistance, of different piston-ring coatings mating with a chrome-plated cylinder liner were investigated. Interrupted wear tests under the lubricant starvation condition were conducted to examine the wear behavior of Cr-diamond coating (GDC) and diamond-like coating (DLC). The results indicated that the DLC coating had outstanding tribological properties (small coefficient of friction and wear loss) at 150 °C, while the GDC coating exhibited better performance at an elevated temperature (240 °C). The DLC coating had a better scuffing resistance; no material adhesion occurred for 70 min under the unlubricated condition. The ...

Load Dependent Microstructural Evolution In An As-Cast 26% Cr High Chromium Cast Iron During Unlubricated Sliding, U. Pranav Nayak, Sebastian Suárez, Valentin Pesnel, Frank Mücklich, María Agustina Guitar

Friction

In the current study, an as-cast 26% Cr high chromium cast iron (HCCI) alloy was subjected to dry-sliding linear wear tests, under different loads. The loads were selected based on analytically computing the critical load (P_C) i.e., the load necessary to induce plastic deformation. The P_C was calculated to be 15 N and accordingly, a sub-critical load (5 N) and an over-critical load (20 N) were chosen. The influence of increasing the load during the wear test was investigated in terms of the matrix microstructural behaviour and its ability to support the surrounding carbides. The morphological aspects ...

Effects Of Imu Sensor Location And Number On The Validity Of Vertical Acceleration Time-Series Data In Countermovement Jumping, Dianne Althouse

All Graduate Plan B and other Reports

Many devices are available for measuring the height of a CMJ. An inertial measurement unit (IMU) measures linear acceleration, orientation, and angular velocity. As an alternative to using IMU estimates of flight time, CMJ height could be estimated by integrating the IMU time-series signal for vertical acceleration to derive CMJ take-off velocity in order to track whole-body center of mass (WBCoM) movement, yet this approach would require valid IMU acceleration data. Thus, the purpose of this study was to quantify the effects of IMU sensor location and number on the validity of vertical acceleration estimation in CMJ. Thirty young adults ...

Novel Patterning Techniques To Improve Digital Image Correlation In Challenging Environments, Weston Craig

All Graduate Theses and Dissertations

A camera-based measurement technique called digital image correlation (DIC) is beneficial to measure displacement and strain in challenging environments (such as post-irradiation evaluation and high temperature environments) due to its non-contacting nature and ability to obtain measurements over multiple length scales. This technique requires a surface pattern which influences the measurement resolution and accuracy of the measurements. This thesis explores two novel patterning techniques to allow the use of DIC in more challenging environments:

The first is to determine if a pattern created from printed text can be used as a pattern in DIC. Native patterns are patterns already present ...

Constructing A Biomimetic Robust Bi-Layered Hydrophilic Lubrication Coating On Surface Of Silicone Elastomer, Luyao Gao, Xiaoduo Zhao, Shuanhong Ma, Zhengfeng Ma, Meirong Cai, Yong-Min Liang, Feng Zhou

Friction

Silicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA–Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on ...

Water Lubrication Of Graphene Oxide-Based Materials, Shaoqing Xue, Hanglin Li, Yumei Guo, Baohua Zhang, Jiusheng Li, Xiangqiong Zeng

Friction

Water is as an economic, eco-friendly, and efficient lubricant that has gained widespread attention for manufacturing. Using graphene oxide (GO)-based materials can improve the lubricant efficacy of water lubrication due to their outstanding mechanical properties, water dispersibility, and broad application scenarios. In this review, we offer a brief introduction about the background of water lubrication and GO. Subsequently, the synthesis, structure, and lubrication theory of GO are analyzed. Particular attention is focused on the relationship between pH, concentration, and lubrication efficacy when discussing the tribology behaviors of pristine GO. By compounding or reacting GO with various modifiers, amounts of ...

Mechanochemical Reactions Of Gan–Al2O3 Interface At The Nanoasperity Contact: Roles Of Crystallographic Polarity And Ambient Humidity, Jian Guo, Jian Gao, Chen Xiao, Lei Chen, Linmao Qian

Friction

Mechanochemical reactions of the GaN–Al₂O₃ interface offer a novel principle for scientific and technological merits in the micro-/nano-scale ultra-precision surface machining. In this work, the mechanochemical reactions on Ga- and N-faced GaN surfaces rubbed by the Al₂O₃ nanoasperity as a function of the environmental humidity were investigated. Experimental results indicate that the N-face exhibits much stronger mechanochemical removal over the relative humidity range of 20%–80% than the Ga-face. Increasing water molecules in environmental conditions significantly promotes the interfacial mechanochemical reactions and hence accelerates the atomic attrition on N-face. The hypothesized mechanism ...

Capillary Electroosmosis Properties Of Water Lubricants With Different Electroosmotic Additives Under A Steel-On-Steel Sliding Interface, Bohua Feng, Zhiqiang Luan, Tao Zhang, Jiawei Liu, Xiaodong Hu, Jiju Guan, Xuefeng Xu

Friction

The process of lubricant penetration into frictional interfaces has not been fully established, hence compromising their tribological performance. In this study, the penetration characteristics of deionized water (DI water) containing an electroosmotic suppressant (cetyltrimethylammonium bromide (CTAB)) and an electroosmotic promoter (sodium lauriminodipropionate (SLI)), were investigated using steel-on-steel friction pairs. The results indicated that the lubricant with electroosmotic promoter reduced the coefficient of friction and wear scar diameter, whereas that with an electroosmotic suppressant exhibited an opposite behavior compared with DI water. The addition of SLI promoted the penetration of the DI water solution, thus resulting in the formation of a ...

Influence Of The Cage On The Migration And Distribution Of Lubricating Oil Inside A Ball Bearing, He Liang, Yu Zhang, Wenzhong Wang

Friction

The migration and distribution of lubricant oil in a rolling bearing strongly affect the elastohydrodynamic lubrication performance between the balls and rings. However, oil re-lubrication is highly dependent on the bearing design, which is different from the ball-on-disc model. This study directly observed the distribution of the lubricant film in a custom-made model-bearing rig, with an outer ring replaced by a glass ring to allow full optical access. The influence of the cage type and surface properties were presented. The physical origin of the re-lubrication mechanism, including capillary flow and mechanical redistribution, was discussed.

Effects Of Annealing Treatment On Tribological Behavior Of Tungsten-Doped Diamond-Like Carbon Film Under Lubrication (Part 2): Tribological Behavior Under Modtc Lubrication, Shaojun Zhang, Lina Zhu, Yanyan Wang, Jiajie Kang, Haidou Wang, Guozheng Ma, Haipeng Huang, Guang’An Zhang, Wen Yue

Friction

Molybdenum dialkyldithiocarbamate (MoDTC) is widely used as a friction modifier in engine lubricating oil. Under MoDTC lubrication, the friction and wear behaviors of tungsten-doped diamond-like carbon (W-DLC) films annealed at 100–400 °C were discussed and evaluated using scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. Under (polymerized alpha olefin) PAO + MoDTC lubrication, the coefficient of friction of all samples decreased, but the wear rates of the W-DLC films annealed at 300 °C increased significantly. By interacting with zinc dialkyldithiophosphate (ZDDP), the wear rates of W-DLC films annealed at different temperatures declined significantly owing to the formation ...

Photorheological Fluids Of Azobenzene Polymers For Lubrication Regulation, Shuangxi Tang, Shayu Li, Liran Ma, Yu Tian

Friction

Fluid viscosity is ubiquitous property and is of practical importance in intelligent fluids, industrial lubrication, and pipeline fluid transportation. Recently, there has been a surging interest in viscosity regulation. Here, we have developed a group of photorheological fluids by utilizing azobenzene polymers with a light-induced microstructure transformation. In this work, a photosensitive polymer with 4,4'-bis-hydroxyazobenzene as the main chain was designed and synthesized as a pivotal functional material. The sufficiently large structural difference under ultraviolet and near-infrared light makes it possible to regulate the viscosity of a polyethylene glycol solution. The viscosity of the photosensitive rheological fluids under ...