Venous thromboembolism (VTE) is the leading cause of preventable death in hospitalized patients. Artificial intelligence (AI) and machine learning (ML) can support guidelines recommending an ...individualized approach to risk assessment and prophylaxis. We conducted electronic surveys asking clinician and healthcare informaticians about their perspectives on AI/ML for VTE prevention and management. Of 101 respondents to the informatician survey, most were 40 years or older, male, clinicians and data scientists, and had performed research on AI/ML. Of the 607 US-based respondents to the clinician survey, most were 40 years or younger, female, physicians, and had never used AI to inform clinical practice. Most informaticians agreed that AI/ML can be used to manage VTE (56.0%). Over one-third were concerned that clinicians would not use the technology (38.9%), but the majority of clinicians believed that AI/ML probably or definitely can help with VTE prevention (70.1%). The most common concern in both groups was a perceived lack of transparency (informaticians 54.4%; clinicians 25.4%). These two surveys revealed that key stakeholders are interested in AI/ML for VTE prevention and management, and identified potential barriers to address prior to implementation.
In this study, buckypaper (BP) membranes have been used to introduce self-sensing capability in glass fiber reinforced polymer matrix (GFRP) laminates by embedding them in the interlaminar region of ...the laminates. Piezoresistive characterization studies were conducted by subjecting the self-sensing GFRP (SGFRP) specimens to cyclic loading and high sensitivity to strain was observed. A measurement model for real-time quantification of fatigue crack, developed using in-situ resistance measurements obtained under fatigue loading, was used to quantify fatigue crack length in real time. The fatigue crack growth rates and the nature of crack propagation in baseline and SGFRP specimens were compared. The results show that the introduction of BP reduced the average crack growth rate by an order of magnitude as a result of crack tip blunting during fatigue, while facilitating real time strain sensing and damage quantification. A fully probabilistic prognosis methodology was also developed by combining the in-situ measurement model with a machine learning based prognosis model to accurately predict the real-time fatigue crack propagation using sequential Bayesian techniques.
Display omitted
Reactive compatibilization of immiscible polymer blends using a preferred compatibilizer leaves the following question: How much loading of a compatibilizer is good enough and what maximum properties ...can be achieved? A good understanding of the process can help solve the reutilization of mixed waste plastics. Here, the reactive compatibilization of polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) on polypropylene/polyamide 66 (PP/PA66) blends is quantitatively assessed using thermorheological, microoptical, spectroscopic, and x‐ray scattering‐based characterization tools. The overall compositions of all PP(60%)/PA66(30%)/PP‐g‐MAH(10%) blends are kept constant while systematically controlling the degree of the chemical reaction by varying the sequential addition of PP‐g‐MAH to the melt mixture. The first feeding of PP‐g‐MAH (x%,0≤x≤10) is conducted at 280°C and the second feeding of (10−x)% is at 200°C. During the first step, a larger amount of chemical activity is observed up to 4%–6% addition of PP‐g‐MAH. The constant chemical composition allows a systematic comparison of the compatibilizer‐dependent thermal, rheological, morphological, and mechanical properties. With an increased degree of interfacial reaction, the size of dispersed PA66 domains decreases to register improved interfacial adhesion with the PP matrix, yielding enhanced Young's modulus and absolute failure strength of the isotropic matrix.
In this study, the reactive compatibilization of polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) on polypropylene/polyamide 66 (PP/PA66) blends is quantitatively assessed using thermorheological, micro‐optical, spectroscopic, and x‐ray scattering‐based characterization tools. The overall compositions of all PP(60%)/PA66(30%)/PP‐g‐MAH(10%) blends are kept constant while systematically controlling the degree of the chemical reaction by varying the sequential addition of PP‐g‐MAH to the melt mixture. The constant chemical composition allows a systematic comparison of the compatibilizer‐dependent thermal, rheological, morphological, and mechanical properties.
An investigation into the damage accumulation and propagation behavior in carbon fiber reinforced polymer (CFRP) composites under complex in-phase biaxial fatigue loading has been conducted. The goal ...is to capture early stage damage and obtain an improved understanding of damage propagation and associated degradation in material properties. Both cross ply and quasi isotropic laminate configurations have been studied and the tests were conducted under constant amplitude in-phase biaxial loading. An optimization technique was used to design the cruciform specimens for each stacking sequence. To understand the propagation of damage from the micro-to the macroscale, the fractured surfaces were analyzed, during various stages of fatigue, using electron microscope assisted fractography and a high-resolution camera. Material property degradation was determined by measuring the change in specimen stiffness to analyze the progression of fatigue damage and is correlated to the micro- and macroscale damage mechanisms and the biaxial fatigue loading parameters. The results provide insight into the initiation and propagation of damage mechanisms in CFRP composites which is essential to understanding the fatigue behavior of composite materials under complex multiaxial loadings.
The crack propagation behavior and the governing crack growth micromechanisms in aluminum alloy under in-plane biaxial fatigue loading with single overloads, of different magnitudes and occurring at ...different fatigue crack lengths, is investigated. The microscale fracture mechanisms governing crack growth behavior under these conditions are identified through detailed fractography. Crack growth retardation behavior observed due to the occurrence of single overloads is correlated with overload magnitude, instantaneous fatigue crack length, crack-tip plasticity and fracture surface morphology. The results obtained provide insight into the relationship between macroscale crack growth behavior to microstructural mechanisms, which is essential to understanding the fatigue behavior of metallic materials under variable amplitude biaxial loading scenarios.
Low density, high strength, and high creep and oxidation resistance properties of ceramic matrix composites (CMCs) make them an ideal choice for use in extreme environments in space and military ...applications. This paper presents a detailed characterization study of structural and manufacturing flaws in Carbon fiber Silicon-Carbide-Nitride matrix (C/SiNC) CMCs at different length-scales. Energy-dispersive spectroscopy (EDS) is used for the chemical characterization of the material’s elemental constituents. High-resolution multiscale graphs obtained from scanning electron microscope (SEM) and confocal laser scanning microscope (LSM) are used to characterize the distribution and morphology of defects at different length scales. This is followed by the classification and quantification of the common manufacturing defects. An image processing algorithm based on the image segmentation process is developed to quantify the variability of various scale-dependent architectural parameters. Finally, a three-dimensional stochastic representative volume element (SRVE) generation algorithm is developed to provide precise representations of material textures at multiple length scales. The developed algorithm accurately accounts for material features and flaws based on a range of multiscale structural and defects characterization results.
This paper presents an experimental investigation into the thermomechanical properties and failure modes of toughened epoxy adhesives and composite-to-aluminum bonded joints in high and low ...temperature conditions. First, nondestructive evaluation techniques were utilized to characterize the inherent defect morphology of bulk adhesives and the bonded joint interface. This was followed by quasi-static tensile testing conducted over a temperature range of −37 °C to 57 °C. The damage mechanisms and failure modes were investigated using in-situ digital image correlation (DIC) and high-resolution camera. The information from the morphology characterization studies was also used to reconstruct high-fidelity geometries of the test specimens for finite element (FE) analysis. The elastic properties and tensile strength of bulk adhesive test specimens showed significant deterioration while exhibiting considerable ductility at higher temperatures. DIC and FE analysis revealed the strong influence of size and distribution of defects on the material properties and damage localization. In addition, post-fracture surface characterization of the adhesively bonded specimens revealed failure modes ranging between adherent-dominant to adhesive-dominant modes at low and high-temperature conditions.
AbstractA detailed ultrasonic cycle fatigue study has been presented for aluminum alloy 7075-T6 (AA7075-T6) under fully reversed tension-compression loading to investigate the geometric sensitivity, ...frequency effects, size effects, surface roughness effects, and the corresponding failure mechanisms across different fatigue regimes. The dominating sources of life variability were identified using sensitivity studies conducted using finite-element analysis (FEA)–based modal and harmonic analyses and probability studies for typical ultrasonic fatigue specimens. In contrast to some studies of crack initiation for aluminum alloys under fatigue, subsurface crack initiations were observed for low stress amplitudes. The presence of both surface and subsurface crack initiations was strongly correlated to the surface conditions and loading conditions. Fatigue-fracture behavior was evaluated via detailed scanning electron microscopy (SEM) analysis of fracture surfaces, exhibiting unique features that are not observed under conventional fatigue testing of aluminum alloys.
AbstractA high-speed manufacturing process for multiwalled carbon nanotube (MWNT) buckypaper is presented, and its application as an embedded strain sensor for composite materials is demonstrated. ...This manufacturing method enables the production of sizable carbon nanotube (CNT) membranes with significantly reduced processing time and less manufacturing complexity than other contemporary techniques. The use of surfactants and chemical functionalization of MWNTs was completely avoided in this method because functionality of carbon nanotubes can be hampered by such surface treatments. Microstructure, mechanical properties, and piezoresistive response of the fabricated buckypaper were characterized, and its sensitivity as a strain sensor was analyzed. Stable piezoresistive response could be achieved at low strains, and a high sensitivity to strain was observed when buckypaper was embedded in glass fiber epoxy laminates for strain sensing.
PDF
