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In this study, the fluid-solid coupling analysis and the pre-deformation optimisation design method of the radome are proposed for the structural deformation of the thin-shell radome under aerodynamic loading. The flow field and structural deformation of the radome are analysed by the fluid-solid coupling analysis. Based on the simulation results, the pre-deformation optimisation method is used to modify the radome shape to compensate for the deformation caused by the aerodynamic load. The optimal pre-deformation parameters are obtained through continuous iteration so that the geometry of the final radome after elastic deformation under the aerodynamic load of the rated working condition is consistent with the geometry of the initial design. The results show that the optimised radome effectively reduces the total radome deformation while maintaining the aerodynamic performance. This study provides an effective fluidstructure coupling analysis and optimisation idea for radome design, which is applicable to the structural design of radomes in the aerospace field.

Many sheet metal parts go through a bending operation during the manufacturing process. Compared to deep-drawing operations, failure in bending operations cannot be predicted accurately with a forming limit curve from the Nakajima or Marciniak experiment, especially in a pre-deformed state. Due to the small bending radii and the associated strong curvature, the failure only occurs with significantly higher strains for states without pre-deformation. Likewise, the failure is not caused by a localization, but by damage to the outer surface of the sample. The introduction of pre-deformation in the sheet material leads to development of texture and damage, where these mechanisms depend on the loading direction. If such pre-deformed sheet material is subsequently bent, the sample may fail unexpectedly early compared to the initial forming limit curve. The present experimental work aims at investigating the influence of pre-deformation and subsequent loading direction for different materials. Therefore, specimens have been pre-deformed in different orientations, followed by bending tests in different orientations. Different pre-deformation levels and loading directions combinations on three sheet materials were investigated. Based on the experimental results a so called bending forming limit curve (BFLC) can be derived enabling enhanced prediction of failure for bending processes after pre-deformation.

Epithelial tissues act as barriers and, therefore, must repair themselves, respond to environmental changes and grow without compromising their integrity. Consequently, they exhibit complex viscoelastic rheological behavior where constituent cells actively tune their mechanical properties to change the overall response of the tissue, e.g., from solid-like to fluid-like. Mesoscopic mechanical properties of epithelia are commonly modeled with the vertex model. While previous studies have predominantly focused on the rheological properties of the vertex model at long time scales, we systematically studied the full dynamic range by applying small oscillatory shear and bulk deformations in both solid-like and fluid-like phases for regular hexagonal and disordered cell configurations. We found that the shear and bulk responses in the fluid and solid phases can be described by standard spring-dashpot viscoelastic models. Furthermore, the solid-fluid transition can be tuned by applying pre-deformation to the system. Our study provides insights into the mechanisms by which epithelia can regulate their rich rheological behavior.

Through a systematic study involving combined pre-deformation (ranging from 0% to 6%) and aging treatment at 175 °C, the influence of precipitates on intergranular corrosion behavior was investigated. The results indicate that, in the under-aged stage, unpredeformed alloys undergo generalized intergranular corrosion due to the continuous distribution of Cu/Li-rich phases along grain boundaries. During peak aging, the uniform precipitation of the T 1 phase within grains inhibits intergranular corrosion propagation, while in the over-aged stage, the coarsening of grain boundary phases and the formation of the precipitate-free zone (PFZ) lead to a transition to pitting corrosion. Upon introducing pre-deformation at 4%-6%, high-density dislocations promote the uniform and dispersed precipitation of the T 1 phase within grains, inhibiting the aggregation of Cu-rich phases at grain boundaries and significantly reducing the tendency towards intergranular corrosion. As the level of pre-deformation increases, the corrosion mode dynamically shifts from localized intergranular corrosion to pitting corrosion. Pre-deformation improves the susceptibility to intergranular corrosion by optimizing the distribution of precipitates (dense within grains and discontinuous at grain boundaries) and balancing the potential difference between grain boundaries and grains.

The investigation examines the impact of pre-deformation on the regulation of precipitate phases in 2099 Al-Li alloy. A 3% pre-deformation increases elastic modulus (from 77.5 GPa to 79.0 GPa), tensile strength (from 544 MPa to 621 MPa), and yield strength (from 414 MPa to 585 MPa), while reducing elongation (from 10.6% to 6.6%). Microstructural analysis shows that pre-deformation refines and homogenizes the T1 and δ´ phases. These modifications have significantly enhanced the mechanical characteristics of the alloy, offering crucial insights for optimizing the processing of 2099 Al-Li alloy, particularly for its use in aerospace applications.

The theoretical and experimental research results of the new method for polymeric materials turning are presented in the article. The workpiece material preliminary deformation by twisting is the distinctive feature of the developed method. It is theoretically shown that the maximum stresses value during twisting is formed on the workpiece surface layer. It has been experimentally proved that the workpiece deformation by twisting leads to changes in the stress-strain state of the polymer chain. The workpieces pre-deformation by twisting allows obtaining the more qualitative surface layer than in case of the traditional turning.

The effect of quasi-static pre-deformation on the dynamic properties of Ti-6Cr-5Mo-5V-4Al titanium alloy was studied. The results revealed that as the pre-tension deformation increased, the average dynamic flow stress was slightly decreased while the dynamic uniform plastic strain and the maximum absorbed energy were improved obviously and the largest value existed when the deformation reached 6.8%. As the pre-tension deformation progressively increased, the dynamic performance exhibited a marked decline. Conversely, with the increase of the pre-compression deformation, the dynamic flow stress experienced a substantial enhancement, but the dynamic uniform plastic and the maximum absorbed energy significantly declined which showed that the pre-compression deformation did harm to the dynamic mechanical properties of Ti-6Cr-5Mo-5V-4Al titanium alloy.

In this brief review, an introduction of the underlying mechanisms for the shape memory effect (SME) and various shape memory phenomena in polymers is presented first. After that, a summary of typical applications in sensors based on either heating or wetting activated shape recovery using largely commercial engineering polymers, which are programmed by means of in-plane pre-deformation (load applied in the length/width direction) or out-of-plane pre-deformation (load applied in the thickness direction), is presented. As demonstrated by a number of examples, many low-cost engineering polymers are well suited to, for instance, anti-counterfeit and over-heating/wetting monitoring applications via visual sensation and/or tactual sensation, and many existing technologies and products (e.g., holography, 3D printing, nano-imprinting, electro-spinning, lenticular lens, Fresnel lens, QR/bar code, Moiré pattern, FRID, structural coloring, etc.) can be integrated with the shape memory feature.

Threaded connections of downhole oil and gas equipment such as tool joints of drill pipes and sucker rod connections operate under difficult conditions of significant cyclic loading and a corrosive environment. This often leads to material fatigue and parts failure. Therefore, the design of such threaded connections requires accurate methods for calculating fatigue life. Using an improved finite element analysis technique in Abaqus/CAE and fe-safe, which takes into account maximum plastic deformation in the first steps of the simulation, the influence of the mechanical characteristics of the materials of these threaded connections on their fatigue life was investigated. An increase in the ductility of the pin or box material leads to equalization of loads along the thread and an increase in the fatigue safety factor, but only if the fatigue strength of this material is sufficient. An additional increase in fatigue life can be achieved by optimal plastic pre-deformation of the connection under a high axial external load. The results prove that the fatigue life of these threaded connections can be significantly improved without optimizing their geometric parameters.

The manufacturing process of launch vehicle storage tanks requires urgent simplification, which can be improved by forming the local features after artificial aging. Therefore, a new process of warm flanging aluminum alloys with pre-deformation was proposed to meet this requirement. The mechanical properties of 2219 aluminum alloy with pre-deformation were investigated at different temperatures using thermomechanical property testing. The deformation law of warm flanging was analyzed through simulation. The flanging limit of 2219 aluminum alloy with pre-deformation was obtained through experiments. Results showed that the ductility of 2219 aluminum alloy with pre-deformation increased then decreased with the increasing temperature, a maximum strain of 0.65 was obtained at 200°C. The equivalent strain gradually rose from the corner zone to the straight wall zone during flanging. The maximum equivalent strain is located at the edge of the straight wall, which gradually decreases with the increasing flanging coefficient. A flanging coefficient of 0.60 can be obtained at 200°C without splitting or seriously thinning. These results guide the local flanging of the integral bottom of 2219 aluminum alloy.