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In large equivalent explosion tests, the method of calculating blast wave parameters by the plastic deformation angle of a cantilever beam can effectively avoid the problem of power supply, storage, communication, and low survival rate of conventional blast wave sensors. In this paper, by means of theoretical analysis and numerical simulation, the deformation response of a pure aluminum cantilever beam with different scaled distances is calculated, and the relationship between the plastic bending angle and blast wave parameters is obtained, which provides a novel and effective method for the measurement of blast wave parameters. The experimental results show that the deformation of the cantilever beam is mainly dominated by the impulse load and the error of this measurement method is within 15%. This method can provide a complementary approach to more precise but complex sensor measurement and can effectively evaluate the impulse in the explosion accident outside. [ABSTRACT FROM AUTHOR]

Extensible or expandable garden hoses have become popular. However, their behavior may be surprising to physicists. In this paper, the stress–strain equations that explain this behavior are derived and compared with experiments. The results clearly demonstrate that, since deformation is very large, conventional definitions of strain and stress are not useful and so-called real definitions are needed instead. [ABSTRACT FROM AUTHOR]

Acoustic metamaterials (AMMs) are designed with complex geometrical shapes to obtain unconventional sound-absorbing performances. As additive manufacturing is particularly suited to print complex structures in a more straightforward and controllable way, AMMs often exploit three-dimensional (3-D) printing techniques. However, when exposed to different temperature conditions, such structures can be affected by geometrical deformations, especially when they are polymer-based. This can cause a mismatch between the experimental data and the expected theoretical performance; therefore, it is important to take thermal effects into account. The present paper investigates the influence of thermal deformations on the sound absorption of three geometries: a coplanar spiral tube, a system with double coiled resonators, and a neck-embedded resonator. Measurements were performed on each 3-D printed specimen in the impedance tube after the samples had been placed in a climate chamber to modify the temperature settings (T = 10–50 °C). Numerical models, validated on the measurements, were employed to quantify the geometrical deformation of AMM structures through a multiphysics approach, highlighting the effects of thermal stress on the acoustic behavior. The main outcomes prove that the frequency shifts of sound absorption peaks depend on temperature configurations and follow exponential regressions, in accordance with previous literature on polymeric materials. [ABSTRACT FROM AUTHOR]

Feldspar vein-intrusive metagabbro is a special geological structure, and different stress angles have an important influence on the fracture mode and deformation characteristics of metagabbro. A Brazilian splitting test on feldspar vein-intrusive metagabbro was performed using three distinct stress angles (0°, 45°, and 90°), and acoustic emission signals and strain characteristics were monitored synchronously during the test. The results showed that the damage pattern of the feldspar vein-intrusive metagabbro was related to the feldspar mineral perforation damage on the main rupture surface. With the increase in stress angle, the percentage of high peak frequency increased gradually. The phenomenon of strain lagging stress appeared in the rock samples before the peak damage. The feldspar minerals played a controlling role in the expansion of microcracks in the feldspar vein-intrusive metagabbro. Significant differences in the local deformation coordination of rocks under different stress angles were observed. The deformation coordination of rock samples with a stress angle of 0° was much lower than that of other rock samples. This study is of great significance for the understanding of the deformation and damage laws of similar geological structures and also provides an important theoretical basis for the stability of deep chambers. [ABSTRACT FROM AUTHOR]

The present article has utilized the WIEN2k computational code to examine the structural, elastic, electronic, magnetic, thermoelectric, and dynamic aspects of the CoCrS Half-Heusler (HH) compound. In this work, calculations have been performed by utilizing the full-potential linearized augmented plane wave method using density functional theory. The electronic bandgap was better interpreted by using the modified Becke–Johnson exchange–correlation functional. We evaluated various electronic properties of the CoCrS HH compound, including band structure plots and density of states. Furthermore, we examined the magnetic characteristics through the computation of magnetic moments and the examination of the spin-polarized electronic state behavior. We also determined the elastic properties of the CoCrS HH compound. These properties, which include stiffness, resilience, and general stability, provide important information about how the material responds to mechanical deformation. Moreover, we explored the electronic structure and found that type 5 of CoCrS exhibits a metallic behavior. In addition, we examined the compound's thermoelectric properties. Finally, the dynamical properties indicate that type 5 of CoCrS is dynamically stable. [ABSTRACT FROM AUTHOR]

Microfluidic phenotyping methods have been of vital importance for cellular characterization, especially for evaluating single cells. In order to study the deformability of a single cell, we devised and tested a tunable microfluidic chip-based method. A pneumatic polymer polydimethylsiloxane (PDMS) membrane was designed and fabricated abutting a single-cell trapping structure, so the cell could be squeezed controllably in a lateral direction. Cell contour changes under increasing pressure were recorded, enabling the deformation degree of different types of single cell to be analyzed and compared using computer vision. This provides a new perspective for studying mechanical properties of cells at the single cell level. HIGHLIGHTS: • A microfluidic chip with pneumatic PDMS membrane was proposed to achieve tunable lateral deformation of single cells. • Controllable cell squeezing was realized to study the deformation degree of single cells. • Computer vision was applied to exact cell contours and the deformation degrees of two cell types were compared. [ABSTRACT FROM AUTHOR]

Numerous mechanically strong and tough soft materials comprising of polymer networks have been developed over the last two decades, motivated by new high-tech applications in engineering and bio-related fields. These materials are characterized by their dynamic complexities and large deformation behaviors. In this Review, we focus on how chain dynamics affects the large deformation and fracture behaviors of soft materials. To favor readers without a rheology background, first we review the linear rheology behaviors of several simple networks. We show that, by playing with the physical entanglement, chemical cross-linking, and physical association of the building polymers, a very rich panel of dynamic responses can be obtained. Then, we show examples of how chain dynamics affects the deformation and fracture behaviors of dually cross-linked hydrogels having chemical cross-linkers and physical bonds. We also provide examples on the unique deformation behavior of physical double-network gels made from triblock polymers. Thereafter, examples of the influence of chain dynamics on the crack initiation and growth behaviors are presented. We show that even for chemically cross-linked double-network hydrogels that exhibit elastic behaviors in a common deformation window, the chain dynamics influences the damage zone size at the crack tip. Finally, we conclude this Review by proposing several directions for future research. [ABSTRACT FROM AUTHOR]

This article presents the design, analysis, and simulation for the klystron coaxial radio frequency (RF) output windows. Three new RF windows (Type-2, 3, and 4) are proposed based on the coaxial RF window with a doorknob structure (Type-1) to improve its performances. The proposed RF windows are simulated in high frequency simulator structure. At the operating frequency, the return loss are obtained as −49, −60, −56, and −52 dB, and the insert loss as −0.003 62, −0.002 51, −0.002 74, and −0.003 dB, respectively, for Type1, 2, 3, and 4. Moreover, for Type-1, the E-field near the short-circuit surface is significantly greater than that near the output port side due to the asymmetrical structure of RF window. However, this phenomenon has been greatly improved in the proposed RF windows. The heat load because of RF power absorption over the ceramic has been calculated. The distribution of heat load in three new windows is more uniform and less than that in Type-1, and the heat load in Type-2 is about half of that in Type-1. The thermal and structural analyses of RF windows predict the lower temperature and less mechanical deformation for the three new RF windows. Multipactor analysis is carried out to determine the safety at the operating power level. [ABSTRACT FROM AUTHOR]

A three-dimensional lattice Boltzmann method, which couples the color-gradient model for two-phase fluid dynamics with a lattice diffusion-advection scheme for the elastic stress tensor, is developed to study the deformation and breakup of a Newtonian droplet in the Giesekus fluid matrix under simple shear flow. This method is first validated by the simulation of the single-phase Giesekus fluid in a steady shear flow and the droplet deformation in two different viscoelastic fluid systems. It is then used to investigate the effect of Deborah number De , mobility parameter α , and solvent viscosity ratio β on steady-state droplet deformation. We find for 0.025 < α < 0.5 that as De increases, the steady-state droplet deformation decreases until eventually approaching the one in the pure Newtonian case with the viscosity ratio of 1 / β , which is attributed to the strong shear-thinning effect at high De. While for lower α , the droplet deformation exhibits a complex nonmonotonic variation with De. Under constant De , the droplet deformation decreases monotonically with α but increases with β. Force analysis shows that De modifies the droplet deformation by altering the normal viscous and elastic stresses at both poles and equators of the droplet, while α mainly alters the normal stresses at the poles. Finally, we explore the roles of De and α on the critical capillary number C a cr of the droplet breakup. By establishing both Ca – De and Ca – α phase diagrams, we find that the critical capillary number increases with De or α except that a plateau critical capillary number is observed in Ca – De phase diagram. [ABSTRACT FROM AUTHOR]

Early detection and monitoring of heavy load induced plastic deformation in the structure is crucial for timely intervention before cracking occurs and the material completely fails. Ultrasound can be used for detecting plastic deformation provided the mechanical modulus, which can be probed via changes in velocities. This work presents a measurement scheme that makes use of optically detected, laser-induced surface acoustic waves (SAWs) for remote, real-time, online monitoring of the wave velocity during the elastic–plastic transition occurring in an aluminum plate undergoing a uniaxial tensile test and a dynamic fatigue test. Monochromatic SAWs were photoacoustically generated in a wavelength-controlled way through a transient thermal grating based laser ultrasonics excitation scheme. The SAWs were detected by a home-built photorefractive interferometer. The results reveal both regions of acceleration and slowing down, indicating that the material first stiffens and then starts to form microcracks that make it behave effectively softer for propagating SAWs. [ABSTRACT FROM AUTHOR]

A key parameter for the performance of ceramic topcoats in a thermal barrier coating is the porosity, which is sensitive to many growing conditions. In the present work, molecular dynamics simulations are performed to investigate the microscopic mechanism for the dependence of the porosity on several experimental conditions in the atmospheric plasma spraying deposition process, including temperature, substrate roughness, and the thickness-to-radius ratio of the yttrium-stabilized zirconia shell. These factors can significantly modify the porosity through changing the buckling mode of the yttrium-stabilized zirconia shell. Our findings provide some microscopic mechanisms for improving the deposition quality of the atmospheric plasma spraying thermal barrier coatings. [ABSTRACT FROM AUTHOR]

Hailstorms cause significant economic losses every year all over the world. Roofs and many other exposed installations can be affected by the impact of hailstones. However, steel resistance to hail impact has not been sufficiently investigated. Predicting the result of hailstone impact is difficult. This can result in significant permanent deformation of the roof. This study aims to develop plastic deformation prediction models for plate structures investigating the plausibility of an equation predicting the dent depth as a function of kinetic energy and yield strength while also addressing the shortcomings of its testing scheme. Causes, results, and solutions to be implemented in the future are also addressed in this work. The proposed equation aims to provide an approximate value for the ratio of dent diameter to dent depth as an input to simplify the solution for the dent depth. For this goal, a new method of making artificial hailstones has been successfully conducted based on the characteristics of natural hailstones. The outcomes of the empirical model were further validated using experimental observations in this study. It was found that within the range of steel sheets tested, the theory gave accurate estimates of the dent depth before the impact. The proposed equation provides insights into the effect of hail impacts on roofs and enables the use of new design methods for the hail resistance of steel sheeting. [ABSTRACT FROM AUTHOR]