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The quarter-wave defect seriously affected the quality of cold rolling products, especially in DP980 dual-phase steel production. The study is the first attempt to use a material model with transverse mechanical properties difference to explore the generation mechanism of DP980 cold rolling quarter-wave. The piecewise function was used to establish a new deformation resistance model of the strip. By this model, the mechanical property can be described in an arbitrary position. A 6-high Universal Crown Control Mill (UCM Mill) implicit FEM model, coupled with the new deformation resistance model was used to complete the research. Analysis based on the simulation results found that the thickness difference between simulation and measure data could be affected by the accuracy of the material model. Based on the multi-stand simulation results, a “local thickness drop” defect was found at 120 mm from the edge of the S3 stand. Through further research of three paths in the elastic–plastic deformation zone of stand S3, it is found that the yield strength (YS) growth rate at 120 mm away from the strip edge is much higher than other locations, which promotes the generation of high-order bending on the work roll surface and lead to the quarter-wave.

An online model is proposed for predicting deformation resistance in the strip tandem cold rolling by combining the back propagation neural network optimized by the mind evolutionary algorithm (MEA-BP) and the deformation resistance analytical model. The real-time collection of hot and cold rolling process data is achieved by constructing a “hot and cold rolling” cross-process data platform. Based on this, a dataset including historical production data of hot and cold rolling is established to train and test the model. The application result of the proposed model shows that the deformation resistance prediction error can be reduced from ±12% to ±5% compared with the traditional analytical model, which demonstrates the model established in this work can effectively improve the prediction accuracy of the deformation resistance in the strip tandem cold rolling.

Crack sealing is an important measure for pavement maintenance. Hot-poured crack sealant is the most utilized material for crack sealing. However, its poor high-temperature and rheological properties seriously weaken the mechanical properties of repaired pavement. Thus, to overcome the disadvantage of the poor high-temperature and rheological properties of sealant, styrene–butadiene–styrene (SBS) and rubber crumb (CR) were utilized for modifying the asphalt-based sealants. Softening point tests, temperature tests, frequency scan tests, and multiple stress creep recovery tests (MSCR) were conducted to evaluate the high-temperature and rheological properties of the modified sealant. Additionally, the influence of SBS and CR on the high-temperature performance of the modified sealant was quantitatively analyzed by the grey relational analysis method. The results reveal that the SBS has a greater enhancement effect on the high-temperature performance of sealant than CR. Increasing the SBS and CR content in the sealant could enhance the sealant’s high-temperature performance, stiffness, and elasticity. Compared with asphalt-based sealant and one-component modified asphalt-based sealant, SBS/CR-modified asphalt sealant has greater viscosity and higher temperature deformation resistance. Additionally, SBS can increase the stress level of the sealant, thereby enhancing the resistance of the sealant to permanent deformation.

Nanoindentation testing using a Berkovich indenter was conducted to explore the relationships among indentation hardness (H), elastic work energy (We), plastic work energy (Wp), and total energy (Wt = We + Wp) for deformation among a wide range of pure metal and alloy samples with different hardness, including iron, steel, austenitic stainless steel (H ≈ 2600–9000 MPa), high purity copper, single-crystal tungsten, and 55Ni–45Ti (mass%) alloy. Similar to previous studies, We/Wt and Wp/Wt showed positive and negative linear relationships with elastic strain resistance (H/Er), respectively, where Er is the reduced Young’s modulus obtained by using the nanoindentation. It is typically considered that Wp has no relationship with We; however, we found that Wp/We correlated well with H/Er for all the studied materials. With increasing H/Er, the curve converged toward Wp/We = 1, because the Gibbs free energy should not become negative when indents remain after the indentation. Moreover, H/Er must be less than or equal to 0.08. Thermodynamic analyses emphasized the physical meaning of hardness obtained by nanoindentation; that is, when Er is identical, harder materials show smaller values of Wp/We than those of softer ones during nanoindentation under the same applied load. This fundamental knowledge will be useful for identifying and developing metallic materials with an adequate balance of elastic and plastic energies depending on the application (such as construction or medical equipment).

In the traditional rolling force model of tandem cold rolling mills, the calculation of the deformation resistance of the strip head does not consider the actual size and mechanical properties of the incoming material, which results in a mismatch between the deformation resistance setting and the actual state of the incoming material and thus affects the accuracy of the rolling force during the low-speed rolling process of the strip head. The inverse calculation of deformation resistance was derived to obtain the actual deformation resistance of the strip head in the tandem cold rolling process, and the actual process parameters of the strip in the hot and cold rolling processes were integrated to create the cross-process dataset as the basis to establish the support vector regression (SVR) model. The grey wolf optimization (GWO) algorithm was used to optimize the hyperparameters in the SVR model, and a deformation resistance prediction model based on GWO–SVR was established. Compared with the traditional model, the GWO–SVR model shows different degrees of improvement in each stand, with significant improvement in stands S3–S5. The prediction results of the GWO–SVR model were applied to calculate the head rolling setting of a 1420 mm tandem rolling mill. The head rolling force had a similar degree of improvement in accuracy to the deformation resistance, and the phenomenon of low head rolling force setting from stands S3 to S5 was obviously improved. Meanwhile, the thickness quality and shape quality of the strip head were improved accordingly, and the application results were consistent with expectations.

With the expanding application of lightweight wooden structures in modern construction, the load-bearing capacity of ordinary triangular single-span wooden trusses limits the applicability of lightweight wooden structures. As a result, triangular multi-span wooden trusses have emerged to replace single-span wooden trusses. In practice, multi-span wooden trusses are composed of multiple single-span lightweight wooden trusses, with connections between members using metal plates, a field that has been relatively well researched. However, connections between spans are primarily made with nails in actual engineering, and there has been little research on the use of wooden pins to connect multi-span wooden trusses. To study the mechanical performance of multi-span wooden trusses connected by wooden pins, this paper innovatively combines existing equipment with a self-designed pulley assembly device to conduct a continuous static full-scale loading test on double-span wooden trusses connected by wooden pins of three different diameters. We comprehensively evaluate which type of wooden pin is more suitable for triangular multi-span wooden trusses. The results indicate that the 16 mm diameter wooden pin provides the best energy dissipation performance for connected beam trusses. The 20 mm diameter wooden pin offers the best performance stability. The 20 mm diameter wooden pin also demonstrates a good load-bearing capacity and resistance to deformation. Overall, the 20 mm diameter wooden pin exhibits the best connection performance in triangular beam trusses.

Materials with structural gradients often have unique combinations of properties. Gradient-structured materials are found in nature and can be engineered. Cheng et al. made a structural gradient by introducing gradients of crystallographic twins into copper. This strategy creates bundles of dislocations in the crystal interiors, which makes the metal stronger than any of the individual components. This method offers promise for developing high-performance metals. Science , this issue p. eaau1925 A structural gradient made of nanotwins improves the strength of copper. Gradient structures exist ubiquitously in nature and are increasingly being introduced in engineering. However, understanding structural gradient–related mechanical behaviors in all gradient structures, including those in engineering materials, has been challenging. We explored the mechanical performance of a gradient nanotwinned structure with highly tunable structural gradients in pure copper. A large structural gradient allows for superior work hardening and strength that can exceed those of the strongest component of the gradient structure. We found through systematic experiments and atomistic simulations that this unusual behavior is afforded by a unique patterning of ultrahigh densities of dislocations in the grain interiors. These observations not only shed light on gradient structures, but may also indicate a promising route for improving the mechanical properties of materials through gradient design.

Glass has outstanding optical properties, hardness, and durability, but its applications are limited by its inherent brittleness and poor impact resistance. Lamination and tempering can improve impact response but do not suppress brittleness. We propose a bioinspired laminated glass that duplicates the three-dimensional “brick-and-mortar” arrangement of nacre from mollusk shells, with periodic three-dimensional architectures and interlayers made of a transparent thermoplastic elastomer. This material reproduces the “tablet sliding mechanism,” which is key to the toughness of natural nacre but has been largely absent in synthetic nacres. Tablet sliding generates nonlinear deformations over large volumes and significantly improves toughness. This nacre-like glass is also two to three times more impact resistant than laminated glass and tempered glass while maintaining high strength and stiffness.

Microstructures that increase metal crystallite size from nanoscale with surface depth are both strong and ductile Steels can be made stronger, tougher, or more resistant to corrosion either by changing composition (adding in more carbon or other elements) or by modifying their microstructures. An extreme microstructural route for strengthening materials is to reduce the crystallite size from the micrometer scale (“coarse-grained”) to the nanoscale. Nanograined aluminum or copper (Cu) may become even harder than high-strength steels, but these materials can be very brittle and crack when pulled (deformed in tension), apparently because strain becomes localized and resists deformation. However, nanograined metals can be plastically deformed under compression or rolling at ambient temperature, implying that moderate deformation can occur if the cracking process is suppressed. Tremendous efforts have been made to explore how to suppress strain localization in tensioned nanomaterials and make them ductile. Gradient microstructures, in which the grain size increases from nanoscale at the surface to coarse-grained in the core, were recently discovered to be an effective approach to improving ductility ( 1 – 4 ).

Nuclear fission of heavy (actinide) nuclei results predominantly in asymmetric mass splits 1 . Without quantum shell effects, which can give extra binding energy to their mass-asymmetric shapes, these nuclei would fission symmetrically. The strongest shell effects appear in spherical nuclei, such as the spherical ‘doubly magic’ (that is, both its atomic and neutron numbers are ‘magic’ numbers) nucleus 132 Sn, which contains 50 protons and 82 neutrons. However, a systematic study of fission 2 has shown that heavy fission fragments have atomic numbers distributed around Z  = 52 to Z  = 56, indicating that the strong shell effects in 132 Sn are not the only factor affecting actinide fission. Reconciling the strong spherical shell effects at Z  = 50 with the different Z values of fission fragments observed in nature has been a longstanding puzzle 3 . Here we show that the final mass asymmetry of the fragments is also determined by the extra stability provided by octupole (pear-shaped) deformations, which have been recently confirmed experimentally around 144 Ba ( Z  = 56) 4 , 5 , one of very few nuclei with shell-stabilized octupole deformation 6 . Using a quantum many-body model of superfluid fission dynamics 7 , we find that heavy fission fragments are produced predominantly with 52 to 56 protons, which is associated with substantial octupole deformation acquired on the way to fission. These octupole shapes, which favour asymmetric fission, are induced by deformed shells at Z  = 52 and Z  = 56. By contrast, spherical magic nuclei are very resistant to octupole deformation, which hinders their production as fission fragments. These findings may explain surprising observations of asymmetric fission in nuclei lighter than lead 8 . Quantum many-body calculations of superfluid fission dynamics reveal that heavy fragments from asymmetric fission of actinides are associated with considerable octupole (pear-shaped) deformation acquired on the way to fission.