Wireless sensor offers impressive functionality compared with traditional wired sensor, including straightforward installation, lightweight, low-cost circuits, high-performance microcontroller and sensors, easy maintenance, and flexibility and scalability for projects. While, there are various challenges to be considered in wireless sensors such as energy efficiency, communication rate, reliability, and data loss. And these drawbacks constrain its applications on specific projects, e.g., long-term monitoring for infrastructures. To overcome the aforementioned drawbacks, this study aims to explore a comprehensive solution from two sides: both the hardware achievement and the communication algorithm. Ultralow power Urbano wireless sensing node with a high-performance computational microcontroller is proposed as the backbone of the wireless sensing system. Satellite communication is employed to ensure the proposed wireless sensing node is completely autonomous to suit a wider range of fields without the requirements of additional base stations (that host single-board computers). In addition, this paper advances compressive sampling (CS) framework as an alternative to traditional Nyquist/Shannon sampling for SHM. An embedded CS-based algorithm is developed to compress the acquired time-history signal, save the storage space of Urbano, reduce data rate requirements, and ensure the accuracy of data via ultra-low rate communication.
Aging water transmission systems in the United States urgently require more efficient approaches to risk management to ensure that systems can operate without failure. Water utilities with spatially vast transmission systems collect extensive data related to the operation of the system, including internal fluid pressures. Combined with representative models that describe both the behavior and condition of the transmission system pipes, a reliability framework can be used to quantify the probability of failure of pipe segments. This work adopts transient pressure data to develop a statistical model of the maximum internal fluid pressures present in a transmission system. This data is combined with an analytical multi-layered ring model of the system pipes to estimate the system reliability. The study adopts the transmission system of the Great Lakes Water Authority (GLWA) to illustrate the use of the reliability framework to estimate the probability of failure of prestressed concrete cylinder pipe (PCCP) segments which have previously experienced failures in many systems across the US.
Osseointegration of a prosthesis offers a novel approach to enhancing the quality of life of an amputee because it makes an artificial limb an integral part of their body. While osseointegrated prostheses offer amputees many benefits, long-term health of the prosthesis fixture in the host bone is a concern. In particular, overloading of the fixture can result in damage to the host bone including bone fracture. This study offers a novel sensing strategy implemented on the percutaneous end of an osseointegrated prosthesis. Piezoelectric actuators are used to generate elastic stress waves in the prosthesis to interrogate the integrity of the prosthesis-bone interface. In this study, flexural mode Rayleigh waves are introduced in the prosthesis to identify the existence and location of fracture in the host bone. A prosthetic model consisting of a titanium rod implanted in a synthetic sawbone with piezoelectric wafer elements bonded to the rod surface is used to validate the proposed approach. The work reveals the waveforms associated with flexural wave modes are directly correlated to bone fracture occurring at the prosthesis-bone interface with fracture location identifiable in the reflect wave features.
A novel d36-type piezoelectric wafer fabricated from lead magnesium niobate-lead titanate (PMN-PT) is explored for the generation of in-plane horizontal shear waves in plate structures. The study focuses on the development of a linear phased array (PA) of PMN-PT wafers to improve the damage detection capabilities of a structural health monitoring (SHM) system. An attractive property of in-plane horizontal shear waves is that they are nondispersive yet sensitive to damage. This study characterizes the directionality of body waves (Lamb and horizontal shear) created by a single PMN-PT wafer bonded to the surface of a metallic plate structure. Second, a linear PA is designed from PMN-PT wafers to steer and focus Lamb and horizontal shear waves in a plate structure. Numerical studies are conducted to explore the capabilities of a PMN-PT-based PA to detect damage in aluminum plates. Numerical simulations are conducted using the Local Interaction Simulation Approach (LISA) implemented on a parallelized graphical processing unit (GPU) for high-speed execution. Numerical studies are further validated using experimental tests conducted with a linear PA. The study confirms the ability of an PMN-PT phased array to accurately detect and localize damage in aluminum plates.
Osseointegrated prostheses which integrate the prosthesis directly to the limb bone are being developed for patients that are unable to wear traditional socket prostheses. While osseointegration of the prosthesis offers amputees improvement in their quality of life, there remains a need to better understand the integration process that occurs between the bone and the prosthesis. Quantification of the degree of integration is important to track the recuperation process of the amputee, guide physical therapy regimes, and to identify when the state of integration may change (due to damage to the bone). This study explores the development of an assessment strategy for quantitatively assessing the degree of integration between an osseointegrated prosthesis and host bone. Specifically, the strategy utilizes a titanium rod prosthesis as a waveguide with guided waves used to assess the degree of integration. By controlling waveforms launched by piezoelectric wafers bonded on the percutaneous tip of the prosthesis, body waves are introduced into the waveguide with wave reflections at the boneprosthesis interface recorded by the same array. Changes in wave energy are correlated to changes at the contact interface between the titanium rod and the bone material. Both simulation and experimental tests are presented in this paper. Experimental testing is performed using a high-density polyethylene (HDPE) host because the elastic modulus and density of HDPE are close to that of human and animal bone. Results indicate high sensitivity of the longitudinal wave energy to rod penetration depth and confinement stress issued by the host bone.
This paper proposes a new way for guided wave structural health monitoring using in-plane shear (d36 type)
piezoelectric wafer active sensors phased arrays. Conventional piezoelectric wafer active sensors phased arrays based on
inducing into specific Lamb wave modes (d31 type) has already widely used for health monitoring of the thin-wall
structures. Rather than Lamb wave modes, the in-plane shear piezoelectric wafer active sensors phased arrays induces in-plane
shear horizontal (SH) guided waves. The SH guided waves are distinct with the Lamb waves with simple
waveform and less additional converted wave modes and the zero symmetric mode (SH0) is non-dispersive. In this paper,
the advantage of the shear horizontal wave and the in-plane shear piezoelectric wafers capability to generate SH waves is
first reviewed. Then finite element analysis of a 4-in-plane shear wafer active sensors phased array embedded on a
rectangular aluminium plate is performed. In addition, numerical simulations with respect to creaks with different sizes
as well as locations are implemented by the in-plane shear wafer active sensors phased array. For comparison purposes,
the same numerical simulations using the conventional piezoelectric wafer active sensors phased arrays are also
employed at the same time. Results indicate that the in-plane shear (d36 type) piezoelectric wafer active sensors phased
arrays has the potential to identify damage location and assess damage severity in structural health monitoring.
This paper proposes a novel and effective method in the field of Non-Destructive Evaluation (NDE). Traditional ultrasonic computerized tomography (UCT) is a heavy task to detect the damages in the object for the numerous measuring times and the huge cost of manual labor. However, utilizing the method proposed in this paper can effectively overcome this great disadvantage, the essence of the application of Compressive Sampling(CS) in the detection of the object is to selectively choose a small quantity of measuring path in the huge number of total measurements. Due to the sparsity of damages in concrete structure, the usage of CS is available. Firstly, we divide the object entirely into numerous grids in order to image the internal situation of the object respectively. Secondly, a measurement matrix to massively decline the quantity of the measuring time should be computed. Thirdly, the travel time of each path we selected according to the matrix should be acquired, utilizing these travel time by adopting the l1-minimization program can we consequently obtained the slowness of the elements inside the object, thus reconstruct the internal situation of the object clearly and effectively. Furthermore, by applying this method we proposed in this paper into the simulation we can not only determine the damage location but also figure the size of it out. Because of the massive decline of the measuring times and accurate reconstruction, we substantiate CS method applied into the monitoring of concrete structure proves to be a shortcut in the field of NDE.
This paper proposes a novel and effective method to identify the damage in the 2-D beam via Lamb wave. Two problems in the structural damage identification: damage location and damage severity are solved based on the theory of compressive sampling (CS) which indicates that sparse or compressible signals can be reconstructed using just a few measurements. Because of the sparsity nature of the damage, a database of damage features is established via a sparse representation for damage identification and assessing. Specifically, this proposed method consists of two steps: damage database establishing and feature matching. In the first step, the features database of both the healthy structure and the damaged structure are represented by the Lamb wave which propagates in the 2-D beam. Then in the matching step, expressing the test modal feature as a linear combination of the bases of the over-complete reference feature database which is constructed by concatenating all modal features of all candidate damage locations builds a highly underdetermined linear system of equations with an underlying sparse representation, which can be correctly recovered by ℓ1-minimization based on CS theory; the non-zero entry in the recovered sparse representation directly identifies the damage location and severity. In addition, numerical simulation is conducted to verify the method. This method of identifying damage location and assessing damage severity, using limited Lamb wave features, obtains good result.
In this paper, a new approach to identify the source location is proposed by exploiting the compressive sensing theory, which indicates that sparse or compressible signals can be recovered using just a few measurement. A square grid configuration plate with some piezoelectric actuator and sensor is used to verify the proposed approach. The grid is used to sweep across the plate to identify the location of source. Piezoelectric actuator placed on the plate is used to excite waves, and the signals of waves received at some sensors. The sensor locations are known, however, the source location need not be known. The candidate source locations are suitably chosen grid on the surface of plate. Sensing matrix which is related to the locations of source and sensor can be calculated at each sensor. Then, the proposed approach used the received signal strengths to locate the source by minimizing the ℓ1-norm of the sparse matrix in the discrete spatial domain based on the concept of compressive sensing (CS). The simulation results show the proposed method achieves a high level of localization accuracy.
Basalt fiber reinforced polymer (BFRP) is a structural material with superior mechanical properties. In
this study, unidirectional BFRP laminates with 14 layers are made with the hand lay-up method. Then,
the acoustic emission technique (AE) combined with the scanning electronic microscope (SEM)
technique is employed to monitor the fatigue damage evolution of the BFRP plates in the fatigue
loading tests. Time-frequency analysis using the wavelet transform technique is proposed to analyze
the received AE signal instead of the peak frequency method. A comparison between AE signals and
SEM images indicates that the multi-frequency peaks picked from the time-frequency curves of AE
signals reflect the accumulated fatigue damage evolution and fatigue damage patterns. Furthermore,
seven damage patterns, that is, matrix cracking, delamination, fiber fracture and their combinations, are
identified from the time-frequency curves of the AE signals.
Stainless Steel Metallic Pseudo Rubber (SSMPR) and Shape Memory Alloy Metallic Pseudo Rubber (SMAMPR) are
novel porous materials with high elasticity and large restorable deformation, and they are also ideal material for three
dimensional isolators or Shock Absorber Devices (SADs). However, the theories on the constitutive model of metallic
rubber are seldom studied due to its complicated microstructure. A theory of contact micro-beams with equal section is
presented in this study, in which the friction between the metal wires in metallic rubber is considered according to
Coulomb's friction law. Firstly, the nonlinear rigidity of the micro-beams in the loading process is derived according to
the simplified mathematical model. Then, the parameters in the theoretic model are also determined through establishing
the relationship between the macro-structure and the micro-structure based on the law of mass conservation and the
probability theory. Especially, the number of contact points between the surfaces of the micro-beams is estimated
according to a mathematical function. Finally, combined with the finite element method, the results of normalized stress-strain
relationships under compression are obtained and compared with the experimental data.
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