Conditional Generative Adversarial Network Enabled Localized Stress Recovery of Periodic Composites

Structural damage in heterogeneousmaterials typically originates frommicrostructures where stress concentration occurs.Therefore,evaluating the magnitude and location of localized stress distributions within microstructures under external loading is crucial.Repeating unit cells(RUCs)are commonly used to represent microstructural details and homogenize the effective response of composites.This work develops a machine learning-based micromechanics tool to accurately predict the stress distributions of extracted RUCs.The locally exact homogenization theory efficiently generates the microstructural stresses of RUCs with a wide range of parameters,including volume fraction,fiber/matrix property ratio,fiber shapes,and loading direction.Subsequently,the conditional generative adversarial network(cGAN)is employed and constructed as a surrogate model to establish the statistical correlation between these parameters and the corresponding localized stresses.The stresses predicted by cGAN are validated against the remaining true data not used for training,showing good agreement.This work demonstrates that the cGAN-based micromechanics tool effectively captures the local responses of composite RUCs.It can be used for predicting potential crack initiations starting from microstructures and evaluating the effective behavior of periodic composites.

Calculation of Electrostatic/Magnetic Adhesion Force Between Adjacent Objects Considering Thin Gap Effect

This paper presents a new approach to evaluating the electrostatic/magnetic adhesion force between two adjacent objects separated by a thin gap.In this approach,instead of generating mesh for the gap,a contact boundary is introduced in the finite element modeling to obtain a reasonable field distribution;then the field in the gap is approximated based on the continuity condition at their interface,so that the adhesion force can be properly calculated.Moreover,a simple equivalent circuit model is introduced to explain how the thin gap influences the adhesion force significantly.Numerical experiments are given to demonstrate the validity of the proposed method and the significance of the thin gap.

Self-powered wireless environmental monitoring system for in-service bridges by galloping piezoelectric-triboelectric hybridized energy harvester

The energy harvesting technology for the ubiquitous natural wind enables a desirable solution to the issue of distributed sensors in the bridge environmental sensing Internet of Things(Io T)system being restricted to conventional energy supply.In this work,a self-powered system based on a compact galloping piezoelectric-triboelectric energy harvester(GPTEH)is developed to achieve efficient wind energy harvesting.The GPTEH is constructed on the prototype of a cantilever structure with piezoelectric macro-fiber composite(MFC)sheets and a rectangular bluff body with triboelectric nanogenerators(TENGs).Through a special swing-type structural design with iron blocks inside the bluff body,the GPTEH exhibits preferable aerodynamic behavior and excellent energy conversion efficiency,compared to conventional cantilever kind of piezoelectric wind energy harvester(PWEH).The GPTEH also demonstrates the capability of high output power density(PEH of 23.65 W m^(-2)and TENG of 1.59 W m^(-2)),superior response wind speed(about 0.5 m s^(-1)),and excellent long-term stability(over 14000 cyclic tests).Furthermore,a power management system is developed to efficiently utilize the output energy from GPTEH to power the sensors and wirelessly transmit environmental data to the terminals.The proposed GPTEH-powered system exhibits a great potential for the bridge environmental monitoring and Io T technologies.

Precast system and assembly connection of cement concrete slabs for road pavement: A review

Prefabricated pavement is increasingly applied worldwide due to the rapid construction on-site.This paper presents a state-of-the-art review of the precast systems and assembly connection of concrete slabs,as well as the precast pavement features.The previous research indicates that:(1)both super-slab and Michigan systems are recommended with the satisfied road performance close to the cast-in-place;(2)flexible base material is suggested for the fabricated pavement for the satisfied leveling and stress distribution;(3)to prevent the voiding phenomenon of the fabricated pavement,the sand cushion course,dry mixed mortar or self-leveling mortar,and other flowable materials could be used for the secondary leveling of the base after the pavement splicing;(4)two-direction dowel bars are recommended for slab connections of the fabricated pavement,which helps to improve the load transfer capacity of the joints and enhance the durability of the fabricated pavement structure;(5)the sealing treatment of precast slab joints needs strengthening to reduce the impact of surface runoff on the base course;(6)the further research focuses are designing with functional,composite,mechanized,intelligent,lightweight,and flexible pavement slabs.Besides,pavement mechanical properties induced by temperature overlapping traffic loads need to be revealed.