Study on Safety Performance of Building Finish Layer under Thermomechanical Coupling Condition

The building finish layer is a comprehensive structural system including the building exterior insulation system and building exterior finish. Combining with buildings has the advantage of reducing wall heat loss and building deformation caused by large temperature differences. Since the building finish layer is prone to cracking, hollowing, and peeling, during the application process, its safety needs to be studied and certified. This study prepares 20 groups of specimens, 15 anchor bolts in each group. The anchor bolt pull-out strength test is carried out. Anchoring damage evolution law and failure mode of anchor bolts are investigated. And the influence of anchoring methods on the pull-out bearing capacity is analyzed. In addition, ABAQUS finite element data simulation is carried out. The stress state of finish in thermomechanical coupling condition and without the effect of temperature are compared and analyzed. The influence factors of anchor bolt pull-out strength and the influence of temperature load on the long-term performance of building finish layer are obtained. The durability of the building finish layer is analyzed. The results show that the anchoring strength of the anchor bolt is positively correlated with the anchoring depth. The anchoring strength is influenced significantly by anchoring construction sequence and temperature. The stress under the coupled effect of temperature and load is greater than that of the single effect of load, and the stress distribution changes significantly. Due to thermal expansion and contraction, the anchor bolt would loosen, which is more prone to damage the building finish layer in a low temperature environment. The weight relationship of each influencing factor of the building finish layer is proposed. A systematic evaluation index system is established. The results of this study provide a basis for subsequent related research work and engineering applications.

Thermomechanical Coupling of a Hyper-viscoelastic Truck Tire and a Pavement Layer and its Impact on Three-dimensional Contact Stresses

A thermomechanical coupling between a hyper-viscoelastic tire and a representative pavement layer was conducted to assess the effect of various temperature profiles on the mechanical behavior of a rolling truck tire. The two deformable bodies, namely the tire and pavement layer, were subjected to steady-state-uniform and non-uniform temperature profiles to identify the significance of considering temperature as a variable in contact-stress prediction. A myriad of ambient, internal air, and pavement-surface conditions were simulated, along with combinations of applied tire load, tire-inflation pressure, and traveling speed. Analogous to winter, the low temperature profiles induced a smaller tire-pavement contact area that resulted in stress localization. On the other hand, under high temperature conditions during the summer, higher tire deformation resulted in lower contact-stress magnitudes owing to an increase in the tire-pavement contact area. In both conditions, vertical and longitudinal contact stresses are impacted, while transverse contact stresses are relatively less affected. This behavior, however, may change under a non-free-rolling condition, such as braking, accelerating, and cornering. By incorporating temperature into the tire-pavement interaction model, changes in the magnitude and distribution of the three-dimensional contact stresses were manifested. This would have a direct implication on the rolling resistance and near-surface behavior of flexible pavements.

Mathematical Analysis of Two Phase Saturated Nanofluid Influenced by Magnetic Field Gradient

Nanofluids are composed of nano-sized particles dispersed in a carrier liquid. The present investigation’s aim is to examine theoretically the magneto-thermomechanical coupling phenomena of a heated nanofluid on a stretched surface in the presence of magnetic dipole impact. Fourier’s law of heat conduction is used to evaluate the heat transmission rate of the carrier fluids ethylene glycol and water along with suspended nanoparticles of a cobalt–chromium–tungsten–nickel alloy and magnetite ferrite. A set of partial differential equations is transformed into a set of non-linear ordinary differential equations via a similarity approach. The computation is performed in Matlab by employing the shooting technique. The effect of the magneto-thermomechanical interaction on the velocity and temperature boundary layer profiles with the attendant effect on the skin friction and heat transfer is analyzed. The maximum and minimum thermal energy transfer rates are computed for the H2O-Fe3O4 and C2H6O2-CoCr20W15Ni magnetic nanofluids. Finally, the study’s results are compared with the previously available data and are found to be in good agreement.

Laser-induced layers peeling of sputtering coatings at 1064 nm wavelength

Large-scale layers peeling after the laser irradiation of dual ion beam sputtering coatings is discovered and a model is established to explain it. The laser damage morphologies relate to the laser fluence, showing thermomechanical coupling failure at low energy and coating layers separation at high energy. High-pressure gradients appear in the interaction between laser and coatings, resulting in large-scale layer separation. A two-step laser damage model including defect-induced damage process and ionized air wave damage process is proposed to explain the two phenomena at different energy. At relatively high energies (higher than 20 J/cm2), ionization of the air can be initiated, leading to a peeling off effect. The peeling effect is related to the thermomechanical properties of the coating materials.

Coupled Thermomechanical Responses of Zirconium Alloy System Claddings under Neutron Irradiation

Zirconium (Zr) alloy is a promising fuel cladding material used widely in nuclear reactors. Usually, it is in service for a long time under the effects of neutron radiation with high temperature and high pressure, which results in thermomechanical coupling behavior during the service process. Focusing on the UO2/Zr fuel elements, the macroscopic thermomechanical coupling responses of pure Zr, Zr-Sn, and Zr-Nb binary system alloys, as well as Zr-Sn-Nb ternary system alloy as cladding materials, were studied under neutron irradiation. As a heat source, the thermal conductivity and thermal expansion coefficient models of the UO2 core were established, and an irradiation growth model of a pure Zr and Zr alloy multisystem was built. Based on the user material subroutine (UMAT) with ABAQUS, the current theoretical model was implemented into the finite element framework, and the consequent thermomechanical coupling behavior under irradiation was calculated. The distribution of temperature, the stress field of the fuel cladding, and their evolution over time were analyzed. It was found that the stress and displacement of the cladding were sensitive to alloying elements due to irradiated growth.

A Thermomechanical Coupling Constitutive Model of Concrete Including Elastoplastic Damage

The thermomechanical coupling constitutive model of concrete is a critical subject for the theoretical investigation and numerical simulation of the mechanical behaviors of concrete members and structures at high temperature. This paper presents a thermomechanical coupling constitutive model for the description of the mechanical behaviors of concrete at different temperatures. The expression of the elastic strain increment is derived with the free energy function including the temperature variable. The expression of the plastic strain increment is derived from the yield function based on the Drucker–Prager strength criterion. The elastoplastic damage effect is included in this constitutive model. The damage variable is included in the yield function to consider the effect of the damage on the elastoplastic mechanical behaviors of concrete. The proposed constitutive model is validated by the comparison of the simulation results of the uniaxial compression tests of concrete at different temperatures with the corresponding test results. The simulation results accord well with the test results at different temperatures. This indicates that the proposed constitutive model can characterize the mechanical behaviors of concrete at different temperatures with considerable accuracy. The proposed constitutive model was applied to simulate an axially compressive concrete column. The simulation results are consistent with the essential mechanical response behaviors of concrete members at different temperatures.