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Process-induced deformation in composite laminates usually occurs during the curing process and is strongly dependent on the cure parameters. To study the influence of the cure parameters on the warpage deformation, an experimental study was carried out with different heating rates and first dwell times. The full-field process-induced deformation was captured by contactless 3 D scanning system to validate the numerical method. Second, a multi-scale thermo-viscoelastic modeling technique was employed to predict the process-induced deformation. The results showed a good agreement between the simulation and experimental deformation, which demonstrates the effectiveness of the numerical model. The influence of six different cure parameters of the vacuum bagging process on the warping deformation and residual stress were considered in the numerical study. Knee points were found on the curves depicting the influence of cure parameters on the maximum residual deformation. Within the manufacturer’s specified range, a slower heating rate of 1.5°C/min reduced the process-induced deformation by 7%, while the other parameters affected the process-induced deformation by less than 1.4%. Meanwhile, the residual stress was also reduced with a slower heating rate. Consequently, a lower heating rate is suggested to reduce both the process-induced deformation and the residual stress for thin parts or the zero-bleeding process.

An efficient, CO2-tuned and highly selective C–O bond cleavage of N-methylated formanilides with NaBH4 has been achieved. Notably, when using N2 as reaction atmosphere, the reaction gave N-methylaniline as major product via C–N bond hydrogenolysis.

The ballistic impact behavior of hybrid 3-dimentional woven composites (3DWC) is predicted through a novel numerical modeling technique and validated the outcome through experimental data. Continuum shell elements with Hashin failure criterion and cohesive surface contact algorithm with traction separation law are used to predict the damage behavior and failure mechanisms during the impact process at interply and intraply levels. Z-yarns are represented by the connector elements with uniaxial behavior having stress-based failure criterion. The proposed methodology predicted the different damage mechanisms during the impact process in comparison with the experimental data and estimated the residual velocities with acceptable accuracy. Different failure mechanisms incurred due to the hybrid nature of the material are also captured by the numerical simulation and the effect of z-yarns are truly depicted by the use of simple 1D elements over the different phases of perforation process. Overall, the finite element (FE) methodology by using simplest form of the elements, their constitutive and damage behavior gives promising results by sufficiently reducing the computational cost.

To observe the effect of systematic graded rewarming measures on body temperature and prognosis of patients with moderate and severe trauma [revised trauma score (RTS)12] requiring emergency operation.A prospective randomized double-blind controlled study was conducted. From January 2020 to January 2021, 104 patients who underwent emergency trauma surgery in the Second Affiliated Hospital of Wenzhou Medical University were selected as the research object. According to random number table method, the patients were divided into traditional rewarming group and systematic graded rewarming group, with 52 cases in each group. Patients in traditional rewarming group (only record the body temperature without intervention, and start the rewarming process when the body temperature at any time was less than 36 centigrade); the patients in the system graded rewarming group start the preventive measures as soon as they were admitted to the hospital, and record the body temperature. When the body temperature at any time was less than 36 centigrade, start the graded rewarming process. Observe the rewarming effect, coagulation function, blood gas analysis and postoperative anesthesia recovery time of the two groups and final outcome.With the extension of time, the body temperature of the two groups increased gradually. The body temperature of the systematic grade rewarming group was significantly higher than that of the traditional rewarming group at 2 hours after rewarming and at discharge (centigrade: 36.23±0.77 vs. 35.84±0.93 at 2 hours after rewarming, 36.54±0.87 vs. 35.82±0.92 at discharge, both P0.05). The incidence of subsequent hypothermia was significantly lower than that in the traditional rewarming group [7.7% (4/52) vs. 25.0% (13/52), P0.05]. The postoperative activated partial thromboplastin time (APTT) of the two groups was significantly shorter than that at admission (s: 35.74±8.05 vs. 45.55±28.02 in the systematic rewarming group, P0.05; 38.35±6.48 vs. 42.40±13.18 in the traditional rewarming group, P0.05); the intraoperative and postoperative pH values in the systematic rewarming group were significantly higher than those at admission (7.33±0.05, 7.36±0.06 vs. 7.30±0.07, both P0.05), while there was no significant difference between the intraoperative and postoperative pH values in the traditional rewarming group and those at admission (7.31±0.06, 7.33±0.06 vs. 7.31±0.05, both P0.05). The postoperative prothrombin time (PT) and anesthesia recovery time in the systematic graded rewarming group were significantly shorter than those in the traditional rewarming group [PT (s): 15.05±2.44 vs. 17.94±3.48, anesthesia recovery time (hours): 14.40±11.76 vs. 17.35±10.51, all P0.05], and the pH value was significantly higher than that in the traditional rewarming group (7.36±0.06 vs. 7.33±0.06, P0.05). The systematic graded rewarming group had higher improvement rate and lower disability rate than the traditional rewarming group (76.9% vs. 65.4% and 17.3% vs. 25.0%, both P0.05).Systematic graded rewarming measures can improve the hypothermia of emergency trauma patients who received surgery, reduce the incidence of subsequent hypothermia of trauma patients, shorten the time of postoperative resuscitation, improve the coagulation function and blood gas indexes, improve the treatment rate, and reduce the incidence of disability.

The Cretaceous nonmarine sedimentary strata are widespread in Songliao Basin, Northeast China. As the largest oil producer in China, an abundance of data has been generated by the petroleum industry, including sedimentology, seismology, geochemistry, and geochronology in the Songliao Basin. This article reviews the achievements in China Cretaceous Continental Scientific Drilling SK and presents the new results of the China Continental Geothermal Drilling SR1 in stratigraphy and geophysics. The results allow us to establish the relationships among SK-1, SK-2, and SR1, provide some constrains on the tectonic setting of Songliao Basin, and interpret the sedimentary facies and environmental evolution. After stratigraphic correlation of SK and SR boreholes, the result indicates that the geological boundary between the late Cretaceous Mingshui formation and the Paleogene Yi’an formation is at the depth of 115 m. The magnetotelluric sounding anomaly areas are corresponding with the unconformities, which are equivalent to seismic horizon T03, T1, T2, and T3, respectively. In addition, the typical “steer’s-head” geometry in the magnetotellurics indicates that the SLB has experienced five evolution stages.

In this paper, a broadband double-layer metamaterial absorber (MMA) based on carbon fibers (CFs) is proposed, which consists of three basic elements. Firstly, the reflectivity of CFs double-layer MMA in normal incidence is analyzed, and compared to the copper double-layer MMA with same size, the simulated results show that it obtains better absorbing effect. With the increase of incident angle, the multi-frequency resonance is activated, leading to larger effective bandwidth. Moreover, when incident angle is between 55 and 70 degrees, the continuous absorption band above 85% can totally cover X and Ku microwave band. Meanwhile, when the EM frequency is at 6-7.5GHz, the change of incident angle hardly affects the absorbing performances of CFs double-layer MMA. A specimen of the CFs double-layer MMA was fabricated by the vacuum bag molding process to verify its effectiveness and the measured results fitted well with the simulated results. In order to discuss the mechanism of EM absorption, the distribution of E-fields and power loss density were monitored. The results indicate that incident angle effects the distribution of E-fields and the way of absorption to change the absorbing performances. The proposed MMA has potential application prospects in the structural and functional integration design of CFs.

Aluminum honeycombs are widely applied in weight sensitive applications, increasing their specific strength and energy absorption capacity are rather important. Thin-walled metallic tube was used to enhance the mechanical properties of aluminum honeycomb and formed a novel tube-reinforced honeycomb structure. Its compressive and three-point bending performances were studied experimentally and numerically. Due to tube filling, the specific compressive strength, elastic modulus and energy absorption have been increased by 16%, 26% and 73%, and the specific bending load and stiffness increased by 42% and 62% respectively. The strengthen mechanism study indicated that the sum of tube and honeycomb caused the increase of compressive properties, and aluminum tube filling changed the stress distribution and expanded the stress concentration region which led to a transformation of bending failure mode. The present reinforcement method will make honeycomb more competitive in light-weight structure applications.

Lead-free dielectric ceramics with both a high recoverable energy storage density (Wrec) and excellent mechanical performance are highly desirable for practical applications in next-generation advanced pulsed power capacitors (APPCs). However, lead-free dielectric ceramics exhibit low Wrec owing to small breakdown strength (Eb) and poor mechanical properties because of their large pore size and low relative density, which restrict devices miniaturization and operation in severe environments. Here, we propose a new strategy, namely, grain size engineering, to develop K0.5Na0.5NbO3 (KNN)-based ceramics with both an extremely high Wrec and large mechanical properties. Interestingly, a large Wrec of 2 J cm−3 was achieved in 0.9K0.5Na0.5NbO3-0.1BiFeO3 (0.9KNN-0.1BF) ceramics at 206 kV cm−1, which is superior to other lead-free dielectric ceramics under moderate electric fields (

Nomex honeycombs are widely used in lightweight structures due to their unique porous structure. By adding an absorbent agent to Nomex honeycomb wall and filling carbon fiber reinforced polymer (CFRP) tube, a novel tube-reinforced absorbent honeycomb sandwich structure was proposed. Its compressive properties and energy absorption characteristics were studied experimentally and numerically. Compared with empty absorbent honeycomb, the normalized elastic modulus E, peak stress and energy absorption of tube-reinforced absorbent honeycomb can be increased by 55.74%, 621.69% and 327.86% respectively. Moreover, the energy absorption of the tube-reinforced absorbent honeycomb was increased by 30.34%, compared with the sum of empty absorbent honeycomb and CFRP tube tested separately. The interaction effects and enhancement mechanism between absorbent honeycomb and CFRP tube were also discussed. The excellent electromagnetic absorption and mechanical properties make this novel honeycomb sandwich structure much more competitive not only in electromagnetic wave stealth application but also in load-carry structures.

Polylactic acid (PLA) hexagonal honeycomb structures were fabricated by using 3D-printing technology. By filling with absorbent polymethacrylimide (PMI) foam, a novel absorbent-foam-filled 3D-printed honeycomb was obtained. The in-plane (L- and W-direction) and out-of-plane (T-direction) compressive performances were studied experimentally and numerically. Due to absorbent PMI foam filling, the elastic modulus, compressive strength, energy absorption per unit volume, and energy absorption per unit mass of absorbent-foam-filled honeycomb under L-direction were increased by 296.34%, 168.75%, 505.57%, and 244.22%, respectively. Moreover, the elastic modulus, compressive strength, energy absorption per unit volume, and energy absorption per unit mass, under W-direction, also have increments of 211.65%, 179.85, 799.45%, and 413.02%, respectively. However, for out-of-plane compression, the compressive strength and energy absorption per unit volume were enhanced, but the density has also been increased, thus, it is not competitive in energy absorption per unit mass. Failure mechanism and dimension effects of absorbent-foam-filled honeycomb were also considered. The approach of absorbent foam filling made the 3D-printed honeycomb structure more competitive in electromagnetic wave stealth applications, while acting simultaneously as load-carrying structures.

A light-weight sandwich structure is designed in this paper to achieve the broadband reflection reduction based on scattering cancellation. The multifunctional sandwich structure is composed of checkerboard metasurface (MS), foam core and carbon fabric/epoxy composite reflector. The checkerboard MS can redirect the incident waves away from the specular direction to achieve the reflection reduction. In addition, the carbon fabric/epoxy composite has the dual role as the reflection layer of incident waves and load bearing face material of whole structure. A series of simulation and optimization results indicate that the whole structure obtains reflection reduction with the reflectivity less than −10 dB in the frequency of 6.7–19.8 GHz under normal incidence, and the reflectivity less than −15 dB in 9.8–14.0 GHz. The proposed structure is lightweight and the density is 0.58 g/cm3. By fabricating the sample, electromagnetic property has been well demonstrated experimentally.

Aluminum foam was limited when applied as load carrying structures for its lower strength. Therefore, an effective enhancement method of aluminum foam was reported in the present study by filling of 304 stainless steel tube into a pre-perforated hole and fixed by epoxy glue. The experimental results indicate that the novel tube enhanced foam (with equivalent density of foam) can doubled the specific compressive strength and energy absorption of that of aluminum foam, and even larger than that of the sum of tube and foam which were tested separately. The coupling strengthening mechanisms are suggested to be the instability limitation of steel tube due to the lateral supports (external and internal) supplied by aluminum foam.

In this study, a closed-cell aluminum foam was filled into the interspaces of a sandwich panel with corrugated cores to form a composite structure. The novel structure is expected to have enhanced foam-filled cores with high specific strength and energy absorption capacity. An out-of-plane compressive load under low-velocity impact was experimentally and numerically carried out on both the empty and foam-filled sandwich panels as well as on the aluminum foam. It is found that the empty corrugated sandwich panel has poor energy absorption capacity due to the core member buckling compared to that of the aluminum foam. However, by the filling of the aluminum foam, the impact load resistance of the corrugated panel was increased dramatically. The loading-time response of the foam-filled panel performs a plateau region like the aluminum foam, which has been proved to be an excellent energy absorption material. Numerical results demonstrated that the aluminum foam filling can decrease the corrugated core member defects sensitivity and increase its stability dramatically. The plastic energy dissipation of the core member for the foam-filled panel is much higher than that of the empty one due to the reduced buckling wavelength caused by the aluminum foam filling.