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The compressive strength of concrete is not the same in high temperature humid environments and normal temperature dry environments. In this study, quasi-static uniaxial compression experiments of concrete with different temperatures and water contents were carried out to investigate the variation pattern of the compressive strength of concrete under combined heat and moisture conditions. The results showed that the temperature softening effect and water softening effect of the compressive strength of concrete were coupled with each other. The compressive strength exhibited a variation trend from increase to decrease with the increase in both temperature and water content, and the relations among the heat–moisture coupling factor, temperature, and relative saturation ratio were obtained. The water absorption of concrete after immersion had a more significant effect on the compressive strength than the free water content stored inside the specimen before immersion. The “pseudo-temperature strengthening effect” distinguished the thermodynamic response of immersed concrete from that of dry concrete, and the functional relationships among the heat–moisture coupling factor, temperature, and relative water absorption ratio were established. The evolutionary mechanism of the competition between the microcrack expansion and healing of concrete under combined heat and moisture conditions was revealed.

The effects of rock softening and shear dilation in the plastic zone are considered to examine the stability of the surrounding rock in deeply buried and weakly cemented soft rock roadways. An elastic-soft fracture mechanical model of the surrounding rock is developed, from which the analytical solutions for the stress and displacement fields are derived, providing expressions for the radius of the plastic zone. This analysis assesses the impact of initial cohesion, internal friction angle, and support force on the stress field, displacement field, and plastic zone radius. The results indicated that the elastic–plastic mechanical model, which considers the softening and shear dilation effects, more accurately represents the deformation characteristics of the roadway’s surrounding rock across the zones of elasticity, softness, and fragmentation. As initial cohesion and internal friction angle increase, the surrounding rock’s load resistance is enhanced, delaying the emergence and expansion of plastic zones. The elastic–plastic interface moves toward the excavation surface, causing a gradual increase in the circumferential stress at the interface. With increasing initial cohesion and internal friction angle, the radius of the plastic zone exhibits a non-linear decrease, with the plastic fracture zone diminishing first. The influence of initial cohesion and internal friction angle on the various zones of surrounding rock is ranked as follows: radius of plastic fracture zone > plastic softening zone > elastic zone. A joint support scheme, incorporating “anchor net and cable injection” with grouting as the core component, is proposed for a project overview of weakly cemented soft rock roadways in the western mining area. This scheme achieves positive outcomes and enhances the safety of roadway construction.

Functional surface with pattern micro-features of sine waves fabricated by ultra-thin metallic sheet is very useful as a shield charactered by variable curvature to diffusely reflect strong light on the severe condition and reduce weight. However, the shape accuracy is difficult to realize using traditional process for the existence of obvious springback. A novel ultrasonic-assisted embossing is developed to precisely fabricate the complex curved surface using its advantages of “Blaha effect.” Some advantages of ultrasonic such as residual softening effect and eliminating residual stress are accepted to reduce the springback micro-features. Effects of embossing parameters were studied by considering the change of strain states. Improvement of shape accuracy by ultrasonic energy and duration time was investigated in the reducing of the springback and increasing of the amplitude of formed sine waves micro-features. Analysis and discussion of the deformation behaviors and springback were carried out in ultrasonic-assisted embossing from the viewpoint of residual acoustic softening effect and eliminating residual stress. Ultrasonic energy and duration time are the main parameters which affect the amplitude of sine waves. Experimental results indicate that the ultrasonic-assisted embossing process is helpful for precisely manufacturing the complex surface with variable curvature using ultra-thin metallic sheet.

Rubber composites are hyperelastic materials with obvious stress-softening effects during the cyclic loading–unloading process. In previous studies, it is hard to obtain the stress responses of rubber composites at arbitrary loading–unloading orders directly. In this paper, a hyper-pseudoelastic model is developed to characterize the cyclic stress-softening effect of rubber composites with a fixed stretch amplitude at arbitrary loading–unloading order. The theoretical relationship between strain energy function and cyclic loading–unloading order is correlated by the hyper-pseudoelastic model directly. Initially, the basic laws of the cyclic stress-softening effect of rubber composites are revealed based on the cyclic loading–unloading experiments. Then, a theoretical relationship between the strain energy evolution function and loading–unloading order, as well as the pseudoelastic theory, is developed. Additionally, the basic constraints that the strain energy evolution function must satisfy in the presence or absence of residual deformation effect are derived. Finally, the calibration process of material parameters in the hyper-pseudoelastic model is also presented. The validity of the hyper-pseudoelastic model is demonstrated via the comparisons to experimental data of rubber composites with different filler contents. This paper presents a theoretical model for characterizing the stress-softening effect of rubber composites during the cyclic loading–unloading process. The proposed theoretical model can accurately predict the evolution of the mechanical behavior of rubber composites with the number of loading–unloading cycles, which provides scientific guidance for predicting the durability properties and analyzing the fatigue performance of rubber composites.

Considering that the traditional Hoek–Brown model only accounts for strain hardening effects in rock materials, while many rock materials exhibit strain softening effects under large deformation, a modified Hoek–Brown model has been developed to simultaneously describe both material hardening and softening characteristics. This enhancement builds upon the traditional Hoek–Brown model by introducing plastic internal variables that characterize material damage or degradation. To address numerical singularities and convergence difficulties encountered during the implementation of the modified Hoek–Brown model, a function smoothing method is employed. The physical significance of model parameters in the modified model is clarified through theoretical analysis and single-factor variable analysis methods. Finally, the modified Hoek–Brown model is applied to practical engineering calculations. The study results demonstrate that the modified Hoek–Brown model can effectively account for both strain hardening and strain softening effects in materials. The function smoothing method proves to be effective in mitigating numerical singularities and convergence issues encountered in the implementation of the modified Hoek–Brown model. For soft rock tunnels, when significant displacements occur in the surrounding rock, both displacements and stresses around the tunnel calculated using the modified Hoek–Brown model are more consistent with engineering reality than those obtained using the traditional Hoek–Brown model. It is recommended to consider applying the modified Hoek–Brown model in practical engineering calculations.

AerMet100 steel is a typical difficult-to-cut material, and laser-assisted milling (LAM) is a promising machining technology for this kind of material. In LAM process, the material is softened by the thermal effect of laser beam, which improves the machinability of the materials. And finally, the cutting forces are reduced compared with conventional milling (CM). This paper presents an analytical model considering material softening effect to predict the cutting force during LAM. The cutting force is produced by shearing and ploughing action. Both laser source and cutting tool are discretized into elements. Based on the Johnson-Cook (J-C) constitutive model and the thermal model due to laser beam and cutting action, the shear plane temperature and the shear flow stress considering the combined effects of laser heating and plastic deformation are calculated iteratively, and the influence of material softening effect on cutting force coefficients is taken into account. A series of experiments carried out on AerMet100 steel demonstrate the accuracy of the cutting force model, and the results show that the three-axis cutting force in LAM is reduced by up to 33.9%. Besides, the influence of laser parameters related to material softening effect on the cutting force is discussed based on the proposed model.

Water-softening effect has been widely recognized as one of the primary causes triggering large deformation and failure in soft-rock engineering; however, there is still a lack of a full-stage constitutive model for rock considering the water-softening effect and non-linear deformation characteristics at the compaction stage under triaxial stress conditions at present. In this paper, laboratory tests are firstly carried out to estimate the deterioration characteristics of mechanical properties with increase of saturation coefficient for shale samples. And then, a full-stage constitutive model of shale subjected to water-softening effect is proposed, which consists of the pre-yield and the post-yield constitutive relationships. The pre-yield constitutive relationships could well describe the non-linear deformation characteristics of compaction stage, which are derived based on the generalized Hooke’s law considering water-softening effect under anisotropic stress conditions. On the other hand, by introducing correction coefficients to solve the problem of numerical discontinuity at the yield point of the pre-yield and the post-yield constitutive relationships, the post-yield constitutive relationships are derived on the basis of the statistical damage mechanics theory. The comparison results with the experimental data show that the proposed model could well characterize the full-stage stress–strain relationship for shale under triaxial loading considering the water-softening effect.

Although the small-scale effect and the material nonlinearity significantly impact the mechanical properties of nanobeams, their combined effects have not attracted the interest of researchers. The present paper proposes two new nonlinear nonlocal Euler–Bernoulli theories to model mechanical properties corresponding to extensible or inextensible nanobeams. Two new theories consider the material nonlinearity and the small-scale effect induced by the nonlocal effect. The new models are used to analyze the static bending and the forced vibrations for single-walled carbon nanotubes (SWCNTs). The results indicate that the material nonlinearity and the nonlocal effect significantly impact SWCNT’s mechanical properties. Therefore, neglecting the two factors may cause qualitative mistakes.

In this article, a recent formulation for real-time simulation is developed combining the strain energy density of the Spring Mass Model (SMM) with the equivalent representation of the Strain Energy Density Function (SEDF). The resulting Equivalent Energy Spring Model (EESM) is expected to provide information in real-time about the mechanical response of soft tissue when subjected to uniaxial deformations. The proposed model represents a variation of the SMM and can be used to predict the mechanical behavior of biological tissues not only during loading but also during unloading deformation states. To assess the accuracy achieved by the EESM, experimental data was collected from liver porcine samples via uniaxial loading and unloading tensile tests. Validation of the model through numerical predictions achieved a refresh rate of 31 fps (31.49 ms of computation time for each frame), achieving a coefficient of determination R2 from 93.23% to 99.94% when compared to experimental data. The proposed hybrid formulation to characterize soft tissue mechanical behavior is fast enough for real-time simulation and captures the soft material nonlinear virgin and stress-softened effects with high accuracy.

The softening effect, which occurs as an undesirable consequence of microstructural changes in the heat-affected zone as a result of the welding process, is an inherent aspect of welding high-strength low-alloyed steels. One of the recommended ways to minimize these changes is the application of laser beam welding as a lower heat input technology. Hence, this work compares and investigates the effects of laser beam welding on the weld joint properties of S690QL, S960QL, S1100QL, S700MC, S960MC, and S1100MC steels. This research operates on the assumption that the mechanical properties of the zones surrounding the soft zone—base metal and weld metal—affect the mechanical properties of weld joints as well. The work shows that the total value of yield strength, tensile strength, and elongation of welded joints increases when the value of the strength of the weld metal and the soft zone increases and when the width of the soft zone narrows, and vice versa. Furthermore, the study demonstrates that the amount of C, Cr, Mn, Mo, Cu, and Ni in steel as well as the thermal cycle is directly associated to strength in these zones. The findings indicate that although the welded joints’ yield strength and tensile strength values remained over 96% of the base metal’s value, in certain cases the elongation values decreased to a mere 21% of the base metal’s value.