Mechanics of Materials Commons^™

Ultrasound-Activated Ciliary Bands For Microrobotic Systems Inspired By Starfish, Cornel Dillinger, Nitesh Nama, Daniel Ahmed

Department of Mechanical and Materials Engineering: Faculty Publications

Cilia are short, hair-like appendages ubiquitous in various biological systems, which have evolved to manipulate and gather food in liquids at regimes where viscosity dominates inertia. Inspired by these natural systems, synthetic cilia have been developed and utilized in microfluidics and microrobotics to achieve functionalities such as propulsion, liquid pumping and mixing, and particle manipulation. Here, we demonstrate ultrasound-activated synthetic ciliary bands that mimic the natural arrangements of ciliary bands on the surface of starfish larva. Our system leverages nonlinear acoustics at microscales to drive bulk fluid motion via acoustically actuated small-amplitude oscillations of synthetic cilia. By arranging the planar …

Preperitoneal Insufflation Pressure Of The Abdominal Wall In A Porcine Model, Riley E. Reynolds, Benjamin Wankum, Sean J. Crimmins, Mark A. Carlson, Benjamin S. Terry

Department of Mechanical and Materials Engineering: Faculty Publications

Background Most complications and adverse events during laparoscopic surgery occur during initial entry into the peritoneal cavity. Among them, preperitoneal insufflation occurs when the insufflation needle is incorrectly placed, and the abdominal wall is insufflated. The objective of this study was to find a range for static pressure which is low enough to allow placement of a Veress needle into the peritoneal space without causing preperitoneal insufflation, yet high enough to separate abdominal viscera from the parietal peritoneum.

Methods A pressure test was performed on twelve fresh porcine carcasses to determine the minimum preperitoneal insufflation pressure and the minimum initial …

Tailoring Texture, Microstructure, And Shape Memory Behavior Of Niti Alloys Fabricated By L-Pbf-Am, Sayed Ehsan Saghaian N.E.

Theses and Dissertations--Mechanical and Aerospace Engineering

Laser Powder Bed Fusion (L-PBF) is one of the most promising Additive Manufacturing (AM) methods to fabricate near net-shape metallic materials for a wide range of applications such as patient-specific medical devices, functionally graded materials, and complex structures. NiTi shape memory alloys (SMAs) are of great interest due to a combination of unique features, such as superelasticity, shape memory effect, high ductility, work output, corrosion resistance, and biocompatibility that could be employed in many applications in automotive, aerospace, and biomedical industries. Due to the difficulties with traditional machining and forming of NiTi components, the ability to fabricate complex parts, tailor …

Determination Of Hydrogel Degradation By Passive Mechanical Testing, Avery Rosh-Gorsky

Honors Theses

This paper details a new technique to measure the mechanical properties of ETTMP PEGDA hydrogels using Hertz Contact Theory and simultaneously analyze both the model drug release and gel erosion in situ. This method involves curing a drug loaded hydrogel in a standard cuvette and placing a glass bead and phosphate buffer solution (PBS). Over time, the cross-linked network of the hydrogel breaks down, and, as a result, the ball sinks into the hydrogel. This method provides a macroscopic and inexpensive way to continuously and passively measure properties of the hydrogel as the hydrogel degrades. By plotting both the …

Timber Bridge Pile Splicing With Fiber Reinforced Polymer Wraps, Drew L. Damich

Graduate Theses, Dissertations, and Problem Reports (ETD)

Timber pile repair using splicing is widely used but little research has been done to determine their strength capacity after repair using this method. Current timber pile splicing mechanisms utilize various steel or wooden components. Fiber Reinforced Polymer (FRP) wraps can be utilized as replacement to conventional materials in splicing of timber piles. This study evaluated the strength capacities of traditional splicing mechanisms in relation to FRP wrap splice mechanisms. Traditional splicing mechanisms consisted of flat steel plate, C-channel steel plate, and wooden plate splices. The FRP wrap splice consisted of unidirectional glass/epoxy composite with three layers of fabric as …

Static And Dynamic Analysis Of Composite Plates Using The Monna Finite Element, Mohamed Emadeldin Omar Abdelhadi

Graduate Theses, Dissertations, and Problem Reports (ETD)

Composite materials are replacing metals in many fields due to their favorable qualities such as strength-to-weight ratio, fatigue characteristics, and corrosion resistance. An efficient, versatile, and accurate composite plate element applicable to the dynamic analysis of composite plates would help the advancement of composites tremendously.

The objective of this research is to analyze composite plates using the classical laminated plate theory (CLPT), first-order deformation theory (FSDT), and higher-order deformation theory (HSDT) with the applicable finite element modeling (FEM) for each theory. This thesis investigates which theory is more efficient and accurate and evaluates the benefits of using an h-p-version …

Application Of Laser Assisted Ultrasonic Nanocrystal Surface Modification On Aluminum And 3d Printed Titanium, Eman Hassan, Thomas Crouse

Williams Honors College, Honors Research Projects

A novel surface treatment, laser assisted ultrasonic nanocrystal surface modification (LA-UNSM), has proved effective in increasing surface hardness, and fatigue life. The objective of this research is to determine the effectiveness of this process on components created with additive manufacturing. To accomplish this, we investigated the effectiveness of LA-UNSM treatment on aluminum, a common 3d printed metal, and the effectiveness of LA-UNSM processing on 3d printed titanium. We first conducted our own literature review to assess the practicality of using this same treatment on aluminum. We then treated traditionally manufactured aluminum at varying levels of laser intensity to determine if …

Surface Strengthening Of Single-Crystal Alumina By High-Temperature Laser Shock Peening, Fei Wang, X. L. Yan, Lei Liu, Michael Nastasi, Yongfeng Lu, Bai Cui

Department of Mechanical and Materials Engineering: Faculty Publications

This manuscript reports a novel process of high-temperature laser shock peening (HTLSP) for surface strengthening of single-crystal ceramics such as sapphire and reveals its fundamental mechanisms. HTLSP at 1200°C can induce a high compressive residual stress on the surface of sapphire while minimize the damage of laser-driven shock waves. Transmission electron microscopy characteriza- tions revealed high dislocation densities near the surface, suggesting that plastic deformation at an ultrahigh strain rate was generated by the high shock wave pressure. The HTLSP-induced compres- sive residual stress can significantly improve the hardness and fracture toughness of sapphire, while maintain its outstanding optical transmittance.

Twinning-Assisted Dynamic Adjustment Of Grain Boundary Mobility, Qishan Huang, Qi Zhu, Yingbin Chen, Mingyu Gong, Jixue Li, Ze Zhang, Wei Yang, Jian Wang, Haofei Zhou, Jiangwei Wang

Department of Mechanical and Materials Engineering: Faculty Publications

Grain boundary (GB) plasticity dominates the mechanical behaviours of nanocrystalline materials. Under mechanical loading, GB configuration and its local deformation geometry change dynamically with the deformation; the dynamic variation of GB deformability, however, remains largely elusive, especially regarding its relation with the frequently-observed GB-associated deformation twins in nanocrystalline materials. Attention here is focused on the GB dynamics in metallic nanocrystals, by means of well-designed in situ nanomechanical testing integrated with molecular dynamics simulations. GBs with low mobility are found to dynamically adjust their configurations and local deformation geometries via crystallographic twinning, which instantly changes the GB dynamics and enhances the …

Development Of An Injectable Methylcellulose Hydrogel System For Nucleus Pulposus Repair And Regeneration, Nada A. Haq-Siddiqi

Dissertations and Theses

Low back pain is the most common cause of disability in the world and is often caused by degeneration or injury of the intervertebral disc (IVD). The IVD is a complex, fibrocartilaginous tissue that allows for the wide range of spinal mobility. Disc degeneration is a progressive condition believed to begin in the central, gelatinous nucleus pulposus (NP) region of the tissue, for which there are few preventative therapies. Current therapeutic strategies include pain management and exercise, or surgical intervention such as spinal fusion, none of which address the underlying cause of degeneration. With an increasingly aging population, the socioeconomic …

In-Situ Process Monitoring For Metal Additive Manufacturing (Am) Through Acoustic Technique, Md Shahjahan Hossain

College of Graduate Studies: Theses & Dissertations

Additive Manufacturing (AM) is currently a widely used technology in different industries such as aerospace, medical, and consumer products. Previously it was mainly used for prototyping of the products, but now it is equally valuable for commercial product manufacturing. More profound understanding is still needed to track and identify defects during the AM process to ensure higher quality products with less material waste. Nondestructive testing becomes an essential form of testing for AM parts, where AE is one of the most used methods for in situ process monitoring. The Acoustic Emission (AE) approach has gained a reputation in nondestructive testing …

Direct Numerical Simulation Of A Pulsatile Flow In A Stenotic Channel Using Immersed Boundary Method, Siamak Mirfendereski, Jae Sung Park

Department of Mechanical and Materials Engineering: Faculty Publications

A three-dimensional direct numerical simulation model coupled with the immersed boundary method has been developed to simulate a pulsatile flow in a planar channel with single and double one-sided semicircular constrictions. For relevance to blood flow in large arteries, simulations have been performed at Reynolds numbers of 750 and 1000. Flow physics and resultant wall shear stress (WSS)-based hemodynamic parameters are presented. The instantaneous vortex dynamics, mean flow characteristics, and turbulent energy spectra are evaluated for flow physics. Subsequently, three WSS-based parameters, namely the time-averaged WSS, oscillatory shear index, and relative residence time, are calculated over the stenotic wall and …

Large-Scale Synthesis Of Compressible And Re-Expandable Three-Dimensional Nanofiber Matrices, Alec Mccarthy, Lorenzo Saldana, Daniel Mcgoldrick, Johnson V. John, Mitchell Kuss, Shixuan Chen, Bin Duan, Mark A. Carlson, Jingwei Xie

Department of Mechanical and Materials Engineering: Faculty Publications

Due to their biomimetic properties, electrospun nanofibers have shown great potential in many biomedical fields. However, traditionally-produced nanofibers are typically two-dimensional (2D) membranes limiting their applications. Herein, we report a large-scale synthesis of compressible and reexpandable three-dimensional (3D) nanofiber matrices for potential biomedical applications. The reproducible mass production of such matrices is achieved using a multiple-emitter electrospinning machine with a controlled environment (e.g., temperature, humidity, and air flow rate) followed by an innovative gas-foaming expansion. The modified 20-emitter circular array with 3D-printed needle caps is capable of maintaining stable Taylor cones under extremely high flow rates. The introduction of such …

A Novel Large Animal Model Of Smoke Inhalation-Induced Acute Respiratory Distress Syndrome, Premila D. Leiphrakpam, Hannah R. Weber, Andrea Mccain, Roser Romaguera Matas, Ernesto Martinez Duarte, Keely L. Buesing

Department of Mechanical and Materials Engineering: Faculty Publications

Background: Acute respiratory distress syndrome (ARDS) is multifactorial and can result from sepsis, trauma, or pneumonia, amongst other primary pathologies. It is one of the major causes of death in critically ill patients with a reported mortality rate up to 45%. The present study focuses on the development of a large animal model of smoke inhalation-induced ARDS in an effort to provide the scientific community with a reliable, reproducible large animal model of isolated toxic inhalation injury-induced ARDS. Methods: Animals (n=21) were exposed to smoke under general anesthesia for 1 to 2 h (median smoke exposure=0.5 to 1 L of …

Assembly Of Close-Packed Ferroelectric Polymer Nanowires Via Interface-Epitaxy With Res2, Dawei Li, Shuo Sun, Kun Wang, Zahra Ahmadi, Jeffrey E. Shield, Stephen Ducharme, Xia Hong

Department of Mechanical and Materials Engineering: Faculty Publications

The flexible, transparent, and low-weight nature of ferroelectric polymers makes them promising for wearable electronic and optical applications. To reach the full potential of the polarization-enabled device functionalities, large-scale fabrication of polymer thin films with well-controlled polar directions is called for, which remains a central challenge. The widely exploited Langmuir–Blodgett, spin-coating, and electrospinning methods only yield polymorphous or polycrystalline films, where the net polarization is compromised. Here, an easily scalable approach is reported to achieve poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) thin films composed of close-packed crystalline nanowires via interface-epitaxy with 1T′-ReS₂. Upon controlled thermal treatment, uniform P(VDF-TrFE) films restructure into …

Reducing Corrosion Of Additive Manufactured Magnesium Alloys By Interlayer Ultrasonic Peening, M. P. Sealy, R. Karunakaran, S. Ortgies, G. Madireddy, A. P. Malshe, K. P. Rajurkar

Department of Mechanical and Materials Engineering: Faculty Publications

Additive manufad (AM) magn alloys corrode rapidly due to tensile stress and coarse microstructures. Cyclically combining (hybridizing) additive manufacturing with interlayer ultrasonic peening was proposed as a solution to improve corrosion resistance of additive manufactured magnesium WE43 alloy through strengthening mechanisms and compressive residual stress. Applying interlayer peening work hardened discrete layers and formed a glocal integrity of regional grain refinement and subsurface compressive residual stress barriers. Tensile residual stress that typically accelerates corrosion decreased 90%. Results showed time-resolved control over corrosion was attainable by interlayer peening, and local corrosion within print cells decreased 57% with respect to as-printed WE43.

Ultra-Fast Charging In Aluminum-Ion Batteries: Electric Double Layers On Active Anode, Xuejing Shen, Tao Sun, Lei Yang, Alexey Krasnoslobodtsev, Renat F. Sabirianov, Michael P. Sealy, Wai-Ning Mei, Zhanjun Wu, Li Tan

Department of Mechanical and Materials Engineering: Faculty Publications

With the rapid iteration of portable electronics and electric vehicles, developing high-capacity batteries with ultra-fast charging capability has become a holy grail. Here we report rechargeable aluminum-ion batteries capable of reaching a high specific capacity of 200 mAh g^−1. When liquid metal is further used to lower the energy barrier from the anode, fastest charging rate of 10⁴ C (duration of 0.35 s to reach a full capacity) and 500% more specific capacity under high-rate conditions are achieved. Phase boundaries from the active anode are believed to encourage a high-flux charge transfer through the electric double layers. As …

Electron Microscopy Observation Of Electric Field-Assisted Sintering Of Stainless Steel Nanoparticles, Fei Wang, Qin Zhou, Xing-Zhong Li, Yongchul Yoo, Michael Nastasi, Bai Cui

Department of Mechanical and Materials Engineering: Faculty Publications

The intrinsic role of electrical current on the electric field-assisted sintering (EFAS) process of stainless steel 316L nanoparticles has been revealed by both ex situ and in situ experiments. A novel device on the Si chip has been designed and fabricated to fit into the sample holder of a transmission electron microscope for these experiments. The evolution of nanoparticle morphology and microstructures during the EFAS process has been studied using scanning electron microscopy and transmission electron microscopy, which has been combined with the simultaneous measurement of the electric voltage and current changes. A preliminary four-stage mechanism for the EFAS process …

Nondestructive Evaluation Of Aluminium Foam Panels Subjected To Impact Loading, Gabriella Epasto, Fabio Distefano, Hozhabar Mozafari, Emanoil Linul, Vincenzo Crupi

Department of Mechanical and Materials Engineering: Faculty Publications

Aluminium foam sandwich structures have excellent energy absorption capacity, combined with good mechanical properties and low density. Some of the authors of this paper proposed an innovative Metallic Foam Shell protective device against flying ballast impact damage in railway axles. A closed-cell aluminium foam was chosen for the Metallic Foam Shell device. The main goal of this study was the experimental investigation of the impact responses of aluminium foam panels. Low velocity impact tests were carried out at different energies on different types of aluminium foam panels in order to investigate the effects of some parameters, such as core thickness, …

The Role Of Microenvironmental Cues And Mechanical Loading Milieus In Breast Cancer Cell Progression And Metastasis, Brandon D. Riehl, Eunju Kim, Tasneem Bouzid, Jung Yul Lim

Department of Mechanical and Materials Engineering: Faculty Publications

Cancer can disrupt the microenvironments and mechanical homeostatic actions in multiple scales from large tissue modification to altered cellular signaling pathway in mechanotransduction. In this review, we highlight recent progresses in breast cancer cell mechanobiology focusing on cell-microenvironment interaction and mechanical loading regulation of cells. First, the effects of microenvironmental cues on breast cancer cell progression and metastasis will be reviewed with respect to substrate stiffness, chemical/topographic substrate patterning, and 2D vs. 3D cultures. Then, the role of mechanical loading situations such as tensile stretch, compression, and flow-induced shear will be discussed in relation to breast cancer cell mechanobiology and …