Free‐Standing and Eco‐Friendly Polyaniline Thin Films for Multifunctional Sensing of Physical and Chemical Stimuli

Multifunctional flexible sensors that are sensitive to different physical and chemical stimuli but remain unaffected by any mechanical deformation and/or changes still present a challenge in the implementation of flexible devices in real‐world conditions. This challenge is greatly intensified by the need for an eco‐friendly fabrication technique suitable for mass production. A new eco‐friendly and scalable fabrication approach is reported for obtaining thin and transparent multifunctional sensors with regulated electrical conductivity and tunable band‐gap. A thin (≈190 nm thickness) freestanding sensing film with up to 4 inch diameter is demonstrated. Integration of the freestanding films with different substrates, such as polyethylene terephthalate substrates, silk textile, commercial polyethylene thin film, and human skin, is also described. These multifunctional sensors can detect and distinguish between different stimuli, including pressure, temperature, and volatile organic compounds. All the sensing properties explored are stable under different bending/strain states.     

A numerical investigation of creep-fatigue life prediction utilizing hysteresis energy as a damage parameter

This paper explores the hypothesis that there exists an intrinsic material property, hysteresis damage energy at failure, which could be used as a creep-fatigue life prediction parameter. The connection between hysteresis energy and fatigue damage was introduced in the 1920’s by Inglis, but the use of hysteresis energy as a measure of damage was first presented by Morrow and Halford. Hysteresis energy shows promise in bridging the gaps associated with life prediction when the combination of both creep and fatigue scenarios are present. Numerical simulations which replicate experimental test configurations with 9Cr–1Mo steel were performed from which the hysteresis energy failure density (HEFD) could be calculated for each experiment. Taking the average of the HEFD values calculated for all of the experimental data as the parameter for failure (E_Intrinsic), creep-fatigue life predictions were made using a simplistic hysteresis energy based method as well as the time fraction/cycle fraction method endorsed by ASME Code and compared to experimental results. A good correlation with experimental results was obtained for life predictions using hysteresis energy density as a damage parameter. An investigation of the interaction between creep damage and fatigue damage based on the hysteresis energy method was also performed and compared with the damage interaction diagram utilized by the ASME and RCC-MR design codes. The hysteresis energy based method proved easy to implement and gave improved accuracy over the time fraction/cycle fraction method for low cycle creep-fatigue loading.     

A simplified ratcheting limit method based on limit analysis using modified yield surface

Two effective approaches for obtaining ratchet boundaries of a structure undergoing cyclic loads are presented. The approaches use limit analysis of a structure whose yield surface is modified according to the cyclic load. In the first approach, Uniform Modified Yield (UMY) surface is used. UMY approach reduces the Mises-based cylindrical yield surface by Mises stress of the cyclic stress amplitude. UMY method was slightly conservative, and sometimes overly conservative, especially at high ratio of cyclic load to primary steady load. Conservatism, caused by the assumption that the modified yield surface remains isotropic, is eliminated by considering anisotropic Load Dependent Yield Modification approach, LDYM. This approach reduces yield strength based on relative orientation of steady primary and cyclic stress tensors. This work assumed elastic perfect plastic material behavior, with no strain hardening for both original and modified yield surfaces. Ratchet boundaries of several structures, published in literature, were obtained using UMY and LDYM approaches and verified against published data and results of conventional methods. Numerical procedures for UMY and LDYM approaches are extremely fast relative to conventional numerical schemes, and are not restricted by complex geometry or loading.     

The role of trust in government in crisis management: Fear of COVID-19 and compliance with social distancing

This study examines the mediating role of trust in government on the relationship between fear of coronavirus disease 2019 (COVID-19) and compliance with social distancing. A cross-sectional survey was conducted among 740 Jordanian citizens, and path analysis (SmartPLS 2.0) was conducted to analyze the data. Results show that fear of COVID-19 has a positive effect on both compliance with social distancing (t = 6.777, p = .000) and trust in government (t = 7.968, p = .000); trust in government has a positive effect on compliance with social distancing (t = 8.502, p = .000); and trust in government partially mediates the relationship between fear of COVID-19 and compliance with social distancing (Sobel test = 6.17, p = .000). The effect of fear of COVID-19 on compliance with social distancing, with trust in the government as a mediating variable, is greater than the direct effect without the mediating variable. Therefore, it is suggested that for social distancing measures imposed by the government on citizens to be effective, policymakers must work to enhance citizens' trust in the government and its measures aimed at curbing the outbreak of COVID-19. Limitations, implications, and suggestions for future research are discussed.