- Award ID(s):
- Publication Date:
- NSF-PAR ID:
- Journal Name:
- NDE 4.0 and Smart Structures for Industry, Smart Cities, Communication, and Energy
- Page Range or eLocation-ID:
- Sponsoring Org:
- National Science Foundation
More Like this
HIGH TEMPERATURE CHARACTERIZATION OF FIBER BRAGG GRATING SENSORS EMBEDDED INTO METALLIC STRUCTURES THROUGH ULTRASONIC ADDITIVE MANUFACTURINGEmbedded fiber Bragg grating (FBG) sensors are attractive for in-situ structural monitoring, especially in fiber reinforced composites. Their implementation in metallic structures is hindered by the thermal limit of the protective coating, typically a polymer material. The purpose of this study is to demonstrate the embedding of FBG sensors into metals with the ultimate objective of using FBG sensors for structural health monitoring of metallic structures. To that end, ultrasonic additive manufacturing (UAM) is utilized. UAM is a solid-state manufacturing process based on ultrasonic metal welding that allows for layered addition of metallic foils without melting. Embedding FBGs through UAM is shown to result in total cross-sectional encapsulation of the sensors within the metal matrix, which encourages uniform strain transfer. Since the UAM process takes place at essentially room temperature, the industry standard acrylate protective coating can be used rather than requiring a new coating applied to the FBGs prior to embedment. Measurements presented in this paper show that UAM-embedded FBG sensors accurately track strain at temperatures higher than 400 C. The data reveals the conditions under which detrimental wavelength hopping takes place due to non-uniformity of the load transferred to the FBG. Further, optical cross-sectioning of the test specimensmore »
Detection of Crack Initiation and Growth Using Fiber Bragg Grating Sensors Embedded into Metal Structures through Ultrasonic Additive ManufacturingStructural health monitoring (SHM) is a rapidly growing field focused on detecting damage in complex systems before catastrophic failure occurs. Advanced sensor technologies are necessary to fully harness SHM in applications involving harsh or remote environments, life-critical systems, mass-production vehicles, robotic systems, and others. Fiber Bragg Grating (FBG) sensors are attractive for in-situ health monitoring due to their resistance to electromagnetic noise, ability to be multiplexed, and accurate real-time operation. Ultrasonic additive manufacturing (UAM) has been demonstrated for solid-state fabrication of 3D structures with embedded FBG sensors. In this paper, UAM-embedded FBG sensors are investigated with a focus on SHM applications. FBG sensors embedded in an aluminum matrix 3 mm from the initiation site are shown to resolve a minimum crack length of 0.286 ± 0.033 mm and track crack growth until near failure. Accurate crack detection is also demonstrated from FBGs placed 6 mm and 9 mm from the crack initiation site. Regular acrylate-coated FBG sensors are shown to repeatably work at temperatures up to 300 ∘ C once embedded with the UAM process.
Additive manufacturing (AM) of complex three‐dimensional (3D) metal oxides at the micro‐ and nanoscales has attracted considerable attention in recent years. State‐of‐the‐art techniques that use slurry‐based or organic–inorganic photoresins are often hampered by challenges in resin preparation and synthesis, and/or by the limited resolution of patterned features. A facile process for fabricating 3D‐architected metal oxides via the use of an aqueous metal‐ion‐containing photoresin is presented. The efficacy of this process, which is termed photopolymer complex synthesis, is demonstrated by creating nanoarchitected zinc oxide (ZnO) architectures with feature sizes of 250 nm, by first patterning a zinc‐ion‐containing aqueous photoresin using two‐photon lithography and subsequently calcining them at 500 ºC. Transmission electron microscopy (TEM) analysis reveals their microstructure to be nanocrystalline ZnO with grain sizes of 5.1 ± 1.6 nm. In situ compression experiments conducted in a scanning electron microscope show an emergent electromechanical response: a 200 nm mechanical compression of an architected ZnO structure results in a voltage drop of 0.52 mV. This photopolymer complex synthesis provides a pathway to easily create arbitrarily shaped 3D metal oxides that could enable previously impossible devices and smart materials.
Experimental Investigation on Forming Limit Curve at Elevated Temperature Through Dome and Biaxial TestThe characteristics of metal and materials are very important to design any component so that it should not fail in the life of the service. The properties of the materials are also an important consideration while setting the manufacturing parameters which deforms the raw material to give the design shape without providing any defect or fracture. For centuries the commonly used method to characterize the material is the traditional uniaxial tension test. The standard has been created for this test by American Standard for Testing Materials (ASTM) – E8. This specimen is traditionally been used to test the materials and extract the properties needed for designing and manufacturing. It should be noted that the uniaxial tension test uses one axis to test the material i.e., the material is pulled in one direction to extract the properties. The data acquired from this test found enough for manufacturing operations of simple forming where one axis stretching is dominant. Recently a sudden increase in the usage of automotive vehicles results in sudden increases in fuel consumption which results in an increase in air pollution. To cope up with this challenge federal government is implying the stricter environmental regulation to decrease air pollution. Tomore »
Purpose Ultrasonic additive manufacturing (UAM) is a solid-state joining technology used for three-dimensional printing of metal foilstock. The electrical power input to the ultrasonic welder is a key driver of part quality in UAM, but under the same process parameters, it can vary widely for different build geometries and material combinations because of mechanical compliance in the system. This study aims to model the relationship between UAM weld power and system compliance considering the workpiece (geometry and materials) and the fixture on which the build is fabricated. Design/methodology/approach Linear elastic finite element modeling and experimental modal analysis are used to characterize the system’s mechanical compliance, and linear system dynamics theory is used to understand the relationship between weld power and compliance. In-situ measurements of the weld power are presented for various build stiffnesses to compare model predictions with experiments. Findings Weld power in UAM is found to be largely determined by the mechanical compliance of the build and insensitive to foil material strength. Originality/value This is the first research paper to develop a predictive model relating UAM weld power and the mechanical compliance of the build over a range of foil combinations. This model is used to develop a toolmore »