High Impact Resistance Research Articles

Drilling process of indexable drill bit based on Coupled Eulerian-Lagrangian method: A simulation study

42CrMo steel has the characteristics of high strength, high wear resistance, high impact resistance, and fatigue resistance. Therefore, drilling 42CrMo steel has always been a challenging task. The indexable drill bit has the advantages of high processing efficiency and low processing cost and has been widely used in the field of aerospace hole processing. To better understand the machining mechanism of the indexable drill bit, this paper uses the Coupled Eulerian-Lagrangian method (CEL) to simulate the three-dimensional drilling model for the first time. The simulation results of the drilling force obtained by the CEL method and Lagrangian method are compared with the experimental results. It is verified that the CEL method is easy to converge and can avoid the problem of program interruption caused by mesh distortion, and the CEL simulation value is more consistent with the actual value. Secondly, the simulation results of cutting force and blade cutting edge node temperature under different process parameters are extracted. The variation of time domain cutting force, frequency domain cutting force and tool temperature with process parameters are obtained. This study provides a new method for the prediction of cutting performance and the optimization of process parameters of indexable drills.

Experimental investigation of perforated multi-layered composite armor subjected to ballistic impact

Ballistic protection of vehicles has become an important endeavor, as it is concerned with how occupants can possess a comfortable feeling together with a high level of protection during a shooting incident. In recent years, numerous forms of armor have employed several kinds of distinct materials to produce a new generation of panels to address the crucial issues in the structure of armor, such as how to provide high protection with reduced density combined with further increasing the stacking and bond strength between the layers of the panel. This study attempts to use a different approach represented by engineering design to combine with the high impact resistance and low weight, moreover high bonding between the laminate of structure. The structure of the suggested armor consists of five main layers made of different materials, FRP composite materials, then two perforated layers of steel, followed by one perforated layer of rubber, and finally one layer of aluminum. These layers were tested via 9 mm caliber to specify the ability of each layer to absorb the energy of the projectile and then the configuration of the layers depending on the function of each layer. However, the results offer a significant ballistic performance with reasonably reduced mass and excellent bonding strength between the layers of the structure.

On the feasibility and the impact resistance of a 3D cross-based fractal produced by powder bed fusion additive manufacturing

Designers have been fascinated by exploring new geometries made by high-performance structures. In more specific terms, biological systems have always been proven to be characterised by sophisticated structures with adapting properties to nature challenges. Insightful analyses have shown how these natural structures are dominated by characteristics such as high energy absorption and elevated strength-weight proportion. Fractal geometries are examples of bio-inspired mathematical objects whose complex 3D structures can be obtained only by advanced manufacturing systems, such as additive manufacturing (AM). This study investigates the feasibility and energy absorption properties of a novel fractal structure based on a 3D Greek cross (3D-CFS). The structure was designed with different volume fractions and produced by powder bed fusion (PBF) AM processes in polyamide (PA12) and thermoplastic polyurethane (TPU). The 3D-CFS properties are investigated under quasi-static and dynamic compression tests. The analysis revealed that for certain geometrical parameters, the manufacturing of the structures is constrained by the sintered powder entrapped in the structure. However, in the case of powder-free structures, the results showed a high impact resistance and cushioning capability. Overall, in terms of specific energy absorption (SEA), the TPU structures showed values between 2.5 and 3.5 kJ/kg, while PA12 ones are between 7.5 and 17.4 kJ/kg, making the 3D-CFS structure compatible with personal protective equipment (PPE) applications. Compared to the literature data on cellular structures made by AM, 3D-CFS performs considerably better. Also, PA12 3D-CFS is better, with a SEA value up to 170% higher than that of a typical material employed for head PPE (e.g. EPS-60 SEA equal to 2.76 kJ/kg). In contrast, TPU 3D-CFS looks more promising in the case of multiple impact conditions.

Nonlinear low-velocity impact analysis of sandwich plates with titanium face sheets and porous aluminum core reinforced by GPLs

This study examines the nonlinear dynamic response of sandwich plates under low-velocity impacts (LVIs), which consist of a porous aluminum foam core with functionally graded (FG) graphene platelets (GPLs) reinforcement and two titanium alloy face sheets. The finite element method is employed to perform the numerical simulations and the Hertz contact theory is used to model the impact behavior. The generic Halpin-Tsai model, which incorporates the porosity effect, is adopted to estimate the mechanical properties of core made of the FG-GPLRC, based on the experimental data of the closed-cell aluminum alloy foam. The simulation results reveal that the FG-X configuration has the highest impact resistance, and that the addition of GPLs improves the impact performance. Moreover, a thicker core can reduce both the first contact time and the vibration period of plates, while a looser boundary condition can prolong the vibration time after the first impact. Additionally, a higher impactor velocity, mass and radius lead to a higher deflection and contact force. The oblique impact decreases the impact energy. This work provides a lighter and stiffer design for structure engineers when components suffer low-velocity impact.

Preparation and properties of hybrid specific length carbon fiber thermoplastic composites by suspension method

AbstractCarbon fiber reinforced thermoplastic composites have such advantages as low density, high strength, high temperature resistance, impact resistance, and good ductility, but due to the density difference between carbon fibers and resin fibers, it is difficult to mix them uniformly. Hence, it is difficult to prepare the composites with the uniform properties. In order to solve this problem, a preparation process based on solid phase mixing of carbon and resin fibers by suspension method is proposed in this paper. The carbon fiber reinforced thermoplastic composites (CFRTPs) can be prepared by dispersing carbon fibers of a certain length (~50 mm) and resin fibers in suspension through ultrasound‐assisted and churn‐combing methods. The effects of carbon fiber length, content and molding process on the mechanical properties of the CFRTPs were studied. The results show that the carbon fiber content and length are the main factors affecting the mechanical properties as well as void ratio of CFRTP. The performance of composites is significantly improved with the increase of carbon fiber length. While the length of carbon fiber is 50 mm and the content is 30 wt%, the prepared CFRTP has the best performance, with the tensile strength of 182.1 MPa, the bending strength of 354.3 MPa, the impact strength of 67.2 KJ·m−2, and the material void ratio of 0.65%. The study shows that the suspension method is feasible for the preparation of the CFRTPs. It is beneficial to improve production efficiency and decrease cost of production for the CFRTPs.Highlights Carbon fiber reinforced thermoplastic composites can be prepared by dispersing carbon fibers of a certain length (~50 mm) and resin fibers in suspension through ultrasound‐assisted and churn‐combing methods. Through the cooling‐high pressure molding process, the porosity of CFRTP is reduced and the mechanical properties of CFRTP are improved. The tensile strength, bending strength, and notch‐free impact strength properties of CFRTP are best when the carbon fiber content is 30% and the CF length is 50 mm. The method is characterized by simple process, low cost and high mechanical properties.

Sound insulation enhancement of polyvinyl butyral film by blending polyurethane and its laminated safety glass

Laminated glass based on PVB film is widely used in military industry and life depending on its excellent safety performance. However, the insufficient sound insulation performance of PVB film restricts its practical application and has gained much more attention. In this work, a PVB-TPU composites with high strength and excellent sound insulation acoustic performance was designed by melt blending method which is attributed to their molecular entanglement and hydrogen bonding interactions between PVB and TPU molecule chains. It has been showed that the maximum tensile strength and elongation at break of the PVB-TPU blending film reached 34 MPa and 235 % respectively when 10 wt% content of TPU in the system. In addition, 20–41 dB of the sound transmission loss (TL) for the composite film with 1 mm thickness in the range of 2000–6000 Hz was achieved, which was obvious enhanced compared with the existing laminated glass intermediate film. The high impact resistance of the laminated glass based on the PVB-TPU film was confirmed by the falling ball impact test. The high sound insulation and safety laminated glass prepared here will be widely used in more fields.

Impact Resistance Enhancement of GLARE Composite Laminates Reinforced with Shape Memory Alloy Wires

This study investigates the impact resistance of Glass Laminate Aluminum Reinforced Epoxy (GLARE) composite laminates by incorporating shape memory alloy (SMA) wires. The influence of varying percentages of pre-strain (0%, 1%, 3%, and 5%) on the SMA wires embedded in the GLARE composites was examined. Laminate composites were made by hand lay-up method using 1100 series aluminum, glass laminate, epoxy resin, and nitinol wire. Impact testing was carried out using the Charpy (un-notched) method. The results demonstrate that the presence of SMA wires significantly enhances the impact resistance of the laminates. The energy absorption capacity of the laminates was found to increase with increasing pre-strain percentage. The highest impact resistance was observed in the specimens with 3% pre-strain, which exhibited a 35.2% increase in energy absorption compared to the specimens without SMA wires. However, a further increase in pre-strain to 5% resulted in a 21.5% decrease in energy absorption due to the higher fraction of stress-induced martensite, limiting the shape memory effect. Additionally, the damage analysis revealed that the absence of SMA wires led to severe debonding and delamination in the GLARE laminates. Conversely, specimens with 3% pre-strain exhibited the least damage, with limited debonding observed only in the front interface of the aluminum and epoxy-laminated fiberglass layers. The higher damage resistance of these specimens is attributed to their optimal energy absorption capability. Based on the findings, it is recommended to further investigate alternative shape memory alloy materials to determine their impact resistance enhancement potential compared to the current SMA wires. Additionally, conducting experiments with pre-strain percentages in the range of 3-5% would provide a better understanding of the maximum achievable performance. Furthermore, microscale observations should be conducted to gain more detailed insights into the damage mechanisms of the tested specimens.

Infill strategies for improving the impact behavior of polymer composites utilizing statistical and thermal analysis

The emergence of additive manufacturing has enabled scientists to efficiently construct complex geometric forms, facilitating the creation of robust structures with enhanced resistance to external forces. Fused filament fabrication (FFF) enables the attainment of personalization, enhanced design flexibility, waste reduction, expedited prototyping, and the generation of intricate profiles. In this study, an impact test was conducted to measure the energy absorption of polymer composites fabricated through fused filament deposition. Specifically, the composites investigated were poly-lactic acid reinforced with multi-walled carbon nanotubes, carbon fibers, and graphene. The study examined the effects of different infill patterns and infill densities on the energy absorption capabilities of these composites. The utilization of a gyroid infill pattern with a 100% infill density has been found to demonstrate the highest level of energy absorption in the context of graphene-reinforced poly-lactic acid. In order to examine the relationship between the given process parameters and the energy-absorbing behavior, an analysis of variance using Taguchi’s approach is employed on the impact test findings. The examination of fractured surfaces using scanning electron microscopy (SEM) unveiled several types of voids, exhibiting enhanced interlayer adhesion in distinct composite materials. The thermal characteristics of the composite material were determined by the utilization of differential scanning calorimetry (DSC) analysis. The experimental results demonstrate that polymer composites have future potential to be employed in automotive parts that necessitate high impact resistance, such as the fabrication of bumpers and body panels.

Strength-toughness matching mechanisms of a boride-reinforced Ti6Al4V compositionally graded material fabricated using spark plasma sintering

In this work, an in-situ boride-reinforced Ti6Al4V compositionally graded material was prepared successfully by spark plasma sintering (SPS), and exhibited a good potential for military application because of its stepwise transition properties from a high-toughness end to a high-strength end along the thin-thickness direction. Microstructure characterization shows the chemical gradient ranged from 0 to 30 wt% TiB2 along the thickness direction, which was correlated with increasing micro-hardness values ranging from 565±5HV to 1270±5HV, respectively. The strength-toughness matching mechanisms of the gradient composites with different compositional gradients were discussed based on the static compression experiments and the dynamic Hopkinson compression rod experiments. The primary phases of the gradient composites included the α-Ti phase, β-Ti phase, remained TiB2 and in-situ formed whisker-like TiB phases. The composites with a compositional gradient of G84 (0, 0, 15, 30 wt%) exhibited the best impact resistance which achieved a good balance of high toughness and strength, and exhibited a compressive strength of 2148±5 MPa and a good elongation of 20 ± 0.5%. The strength-toughness matching mechanisms can be explained by the dispersion strengthening effect due to the presence of the in-situ formed TiB phase, and the consumption of more fracture energy by dislocation defects, which can prevent the crack propagation. Moreover, the pull-out of the whisker-like TiB phases toughened the gradient composites furthermore. This research demonstrated a reliable method for preparing TiB2/Ti–6Al-4Vgradient composites with high-impact resistance.

Finite element analysis of the effect of crystallinity on low-velocity impact performance of poly (aryl ether ketone) composites

A new copolymer poly (aryl ether ketone) (PAEK) resin was used as a matrix to prepare carbon fiber (CF) reinforced composites with different crystallinity by slow and rapid cooling. Finite element (FE) models were constructed according to micromechanics, and the progressive damage method based on the three-dimensional (3D) PUCK damage criterion was used to analyze the low-velocity impact damage mechanism of the CF/PAEK composites. The experimental results show that the composites with lower crystallinity have higher impact resistance and smaller impact damage area. In the FE simulated impact damage evolution process, the damage of the impact side is mainly compressive damage of the matrix and the fiber, while that of the impact back side is mainly tensile damage of the matrix. Moreover, due to their high interfacial bonding strength, the main damage modes of rapid-cooled composites with lower crystallinity are severe matrix tensile damage and slight fiber tensile damage in the impact back side. However, the slow-cooled composites show more delamination. In addition, for the damage evolution of compression after impact, the FE simulation shows that fiber compression, matrix tension, matrix compression and delamination expand along the transverse to the compression load. Furthermore, the in-plane damage expansion occurs earlier in the rapid-cooled composites, which also have graver interlaminar damage.

Numerical simulation on dynamic compression properties of sandstone under axial static preload

In this study, through a series of static mechanical tests and split Hopkinson pressure bar (SHPB) dynamic impact tests, the static and dynamic mechanical parameters of yellow sandstone are determined, and the Holmquist–Johnson–Cook model parameters of the rock are determined by the test data and theoretical calculation. The feasibility of a numerical model is verified, based on which the SHPB impact process under different axial pressure is subjected to numerical analysis. The results show that with increasing impact load, the degree of rock breakage increases, and the dynamic compressive strength and dynamic elastic modulus increase continuously. With the application and increase of axial pressure, the dynamic compressive strength and dynamic elastic modulus of the rock decrease gradually under the same impact load, and the maximum cumulative strain keeps increasing, indicating that under the influence of axial pressure, micro-cracks in the rock have initially developed and expanded. With increasing axial pressure, the rock is more vulnerable to breakage, and its weakening degree keeps increasing. The energy utilization rate of one-dimensional dynamic and static combined loading is affected by the axial compression ratio and impact load. At low axial compression ratio, the rock has high impact resistance but high energy utilization rate; at high axial compression ratio, the rock has low impact resistance but low energy utilization rate. Therefore, the combination of axial compression ratio and impact velocity can improve the crushing effect and energy utilization rate on the premise of clear crushing form requirements.

Unraveling the effects of geometrical parameters on dynamic impact responses of graphene reinforced polymer nanocomposites using coarse-grained molecular dynamics simulations.

Nacre plays an important role in bionic design due to its light weight, high strength, and structure-function integration. The key to elucidate its reinforcing and toughening mechanisms is to truly characterize its multi-layer structure and properties. In this work, the dynamic impact responses of graphene reinforced polymer nanocomposites with a unique brick-and-mortar structure are investigated using coarse-grained molecular dynamics simulations, in which the interfacial coarse-grained force field between graphene and the polymer matrix is derived by the energy matching approach. The influences of various geometrical parameters on dynamic impact responses of the nanocomposites are studied, including the interlayer distance, lateral distance, and number of graphene layers. The results demonstrate that the impact resistance of the nacre-like structure can be significantly improved by tuning the geometrical parameters of graphene layers. It is also found that the chain scission and interchain disentanglement of polymer chains are the main failure mechanisms during the perforation failure process as compared to the stretching and breaking of bonds. In addition, the microstructure analysis is performed to deeply interpret the deformation and damage mechanisms of the nanocomposites during impact. This study could be helpful for the rational design and preparation of graphene reinforced nacre-like nanocomposites with high impact resistance.

Numerical investigation of the low velocity impact behavior of CFRP laminates

The impact response and failure mechanism of carbon fiber reinforced composite laminates under low velocity impact was investigated using ABAQUS®. A finite element model was developed based on the progressive damage theory to study the impact response of CFRP laminates with hemispherical impactor. The impact tests were conducted on cross-ply (0/90)2s and quasi-isotropic, QI (0/45/-45/90)s laminates with different impact velocities. From the numerical simulation, the damage initiation and propagation in the CFRP laminates were found in terms of damage location, size and shape. The intra-laminar damages such as fiber and matrix damages were predicted using in-built Hashin criterion of ABAQUS®. The traction separation based cohesive surface modelling approach was utilized for capturing the inter-laminar failure initiation and propagation induced by impact loading. The numerical results of different impact energy levels were analysed for different failure modes for varying impact force, displacement and kinetic energy. The total volume of fiber damage and the total area of delamination were calculated for each laminate sequence. From numerical simulations, it was observed that the delamination was less on cohesive surfaces above the mid-thickness plane due to high compression through the thickness. The fiber damage was found at 65 J of impact energy. The first load drop was observed in the cross-ply laminates due to the delamination between lamina 5 and 6. The study revealed that the QI laminates had higher impact resistance and smaller damage zone than the cross-ply laminates.

Effects of aging temperature on microstructure and mechanical properties of PH 13-8Mo stainless steel

Precipitation hardening stainless steel (PHSS) possesses high strength, impact resistance, and corrosion resistance, making it extensively employed in aerospace, nuclear power equipment, and petrochemical industries. The precipitates and reversed austenite (RA) generated during heat treatment significantly influence the properties of PHSS. This study investigates the impact of aging temperature (480–620 °C) on PH 13-8Mo stainless steel. As the aging temperature increased from 480 °C to 620 °C, the yield strength (YS) and ultimate tensile strength (UTS) initially increased and then decreased, while the impact energy initially decreased and then increased. At an aging temperature of 510 °C, the strength and hardness reach their maximum values, indicating peak aging conditions. The microstructure after aging treatment is lath martensite, RA and NiAl. With increasing aging temperature, the size of NiAl precipitates increases, accompanied by a rise in RA content. The quantitative analysis assessed the contributions of various strengthening mechanisms (precipitation strengthening, solid solution strengthening, grain refinement strengthening, dislocation strengthening, etc.) to YS. Quantitative calculations revealed that the precipitation strengthening effect was most pronounced at an aging temperature of 510 °C.

Destruction of reinforced concrete structures of sewage systems

Composites materials are artificially created materials that consist of two or more components that differ in composition and are separated by a pronounced boundary. The development of modern composite materials is associated with the discovery of high-strength whiskers, with the study and use of aluminides and high-strength alloys. At present, various composite materials have been developed and used: fibrous; reinforced with whiskers and continuous crystals and fibres of refractory compounds and elements; dispersion-hardened materials; layered materials; alloys with directional crystallization of eutectic structures; alloys with intermetallic hardening. There are many technologies for producing composites: imbibition of reinforcing fibres with matrix (base) material; cold pressing of components followed by sintering; sediment of the matrix by plasma spraying on the hardener, followed by compression; batch diffusion welding of multilayer tapes of components; joint rolling of reinforcing elements with a matrix, and etc. The use of composites makes it possible to reduce the weight of aircraft, cars, ships, increase the efficiency of engines, and create new constructions with high performance and reliability. The development of composites with high impact resistance is an important direction in the industry. The strength characteristics of a layered composite material are decisive under shear loads, loading of the composite in directions other than the orientation of the layers, and cyclic loading. In this paper, we study the non-stationary interaction of an absolutely rigid body on a two-layer reinforced composite material. The action of the striker is replaced by a non-stationary vertical even distributed load, which changes according to a linear function, in the area of initial contact, which is assumed to be unchanged over time.
 In contrast to the previous articles (Parts I and II), in this papers there is an investigation of the strain-stress state, the fields of the Odquist parameter and normal stresses depending on the material of the first (upper) layer.

Experimental investigation and numeric modelling of the impact performance of basalt fiber reinforced geopolymer concrete

Geopolymer concrete (GC) has been found to have better results than Portland cement concrete (PCC), including lower carbon dioxide emissions, higher compressive strength, and greater durability. The study aims to determine the effects of basalt fiber on GC due to the impact caused by the sudden loading effect. Samples were prepared with different mixing ratios for the experimental process, with PCC used as the control sample. Basalt fibers were added to the samples in three different ratios based on optimal mixing ratios determined through physical and mechanical tests, such as UPV (Ultrasonic Pulse Velocity), compressive strength, and flexural strength. Subsequently, fibrous samples were analyzed using SEM (scanning electron microscopy) and EDS (energy dispersive spectroscopy). A drop-weight experiment was conducted on GC plates measuring 50×50×5 cm, which contained two different fiber ratios that yielded the best mechanical and physical properties. The results were analyzed using numerical modeling methods. No changes in content were made. The sample with the highest impact resistance was found to be the 2% basalt fiber-reinforced GC, with a displacement value 21.21% lower than PCC. The language used is clear, concise, and objective, with a formal register and precise word choice. The text follows a logical structure with causal connections between statements and adheres to conventional academic formatting and citation styles. The ANSYS modeling results indicated an 89.63% similarity with the experimental data regarding the displacement values. Additionally, the study demonstrated that the inclusion of basalt fiber additives enhances the impact resistance of geopolymer concrete. Furthermore, numerical modeling can predict the impact behavior of concrete to a significant extent, eliminating the need for experimental processes.

Gorilla Glass Cutting Using Femtosecond Laser Pulse Filaments

Due to high durability, scratch resistance, and impact resistance, Gorilla glasses are a popular choice for protective screens of smartphones, tablets, and laptops. Precise cutting of Gorilla glasses is very important to maintain the overall aesthetics and user experience, which is very challenging. We demonstrated for the first time the cutting of Gorilla glass by means of femtosecond laser filamentation technique. To achieve laser filamentation, a femtosecond laser beam was focused and irradiated in different depths of the sample Gorilla glasses. The filament length varied with the change in the focus position of the laser beam. The effective numerical aperture of the objective lens rises due to the presence of dielectric material (i.e., the Gorilla glass itself) before the focus position of the femtosecond laser beam inside the glass samples. As a consequence, the focal distance of the incident laser beam was prolonged and focused in a very tiny spot with extremely high energy density. Consequently, filaments (i.e., high aspect ratio micro-voids) were evident inside the Gorilla glass samples. The filament length is controllable by changing the irradiation parameters of the laser beam, including magnification and numerical aperture of the lens, laser energy, and thickness of the Gorilla glass before the target focal point. The filament-engraved Gorilla glass samples go through mechanical cleaving process with 400 MPa pressure on both sides of the laser scanning line for smooth cutting of Gorilla glass. The proposed glass cutting technique show promises for commercial application.

Formation of microstructure in rail steel grinding balls depending on quenching medium parameters

Studies of the formation of microstructure of grinding balls from the rejects of rail steel were carried out during their quenching in various polymer media. At the first stage, based on studies of the cooling capacity of solutions of polymers PCM and Thermovit with varying concentrations and temperatures, the authors constructed the cooling curves of grinding balls made of K76F rail steel. It was found that at concentration of these polymers in an aqueous solution of 2 and 4 %, cooling rate of grinding balls made of K76F steel is almost identical at solution temperatures of 20 and 30 °C and significantly decreases when the temperature of the polymer solution increases to 40 °C. At the same time, the most noticeable decrease in the cooling rate is characteristic of PCM polymer with its concentration at the level of 2 %. At the second stage, the authors carried out metallographic studies of the microstructure of grinding balls made of K76F rail steel, which were quenched in laboratory conditions using polymers PCM and Thermovit with concentrations of 2 – 4 % and temperature of 20 – 40 °C. As a result, it was determined that the use of the PCM solution for quenching balls provides a significantly higher quality of microstructure and hardness of heat-treated balls compared to the use of the Thermovit polymer. At the same time, varying the concentration and temperature of the PCM polymer quenching medium allows one to obtain grinding balls with different performance characteristics that determine the potential areas of their application. Thus, quenching of balls in a solution of the specified polymer with concentration of 2 % and temperature of 20 – 30 °C ensures the production of balls with high hardness (corresponding to the IV hardness group according to the state standard GOST 7524 – 2015), and the use of a solution of the same polymer with concentration of 4 % and temperature of 20 – 30 °С for quenching creates the possibility of producing balls with lower hardness, but potentially high impact resistance.

The Influence of Curing System on the Macroscopic Performance and Microstructure of Anti-Abrasive UHPC

In a previous study, we utilized saturated prewet high titanium heavy slag sand to produce UHPC (ST-UHPC). ST-UHPC has high impact and abrasion resistance. For better ST-UHPC applications, we investigate the mechanism of ST-UHPC under different curing systems from the microstructure and macroscopic perspective in this paper. We prepared ST-UHPC under four maintenance conditions: 20 °C standard curing, 90 °C steam curing, 90 °C dry curing and 210 °C 2 MPa pressure steam curing. Then, we analyzed the hydration product composition, the degree of cement hydration, the C-A-S-H gel microstructure and the substitution of Al3+ for Si4+ in relation to these prepared ST-UHPCs. Compared with standard curing, dry curing at 90 °C accelerated the water evaporation and reduced the hydration degree of ST-UHPC cementite. However, pressure steam curing significantly improved the hydration degree of ST-UHPC cementing material, and increased the MCL and Al[4]/Si of C-A-S-H gel. In addition, pressure steam curing reduced the Ca/Si and promoted the conversion of C-A-S-H cementing to tobermorite. Compared with dry curing at 90 °C, pressure steam curing significantly improved the macroscopic properties of ST-UHPC. The macro-performance difference of ST-UHPC under standard curing and 90 °C steam curing is small. The reason is that steam curing caused the water to be rapidly released in the internal aggregate of ST-UHPC. This resulted in the increase of the interface between the internal aggregate of ST-UHPC and the ST-UHPC cementate. The harmful pores in the ST-UHPC matrix under steam curing were also increased. To sum up, compared with standard curing, dry curing at 90 °C weakened the mechanical properties and microstructure of ST-UHPC, but steam pressure curing increased them. The single steam curing had no significant effect on the mechanical properties and microstructure of the ST-UHPC. Therefore, non-steam and room-temperature moisturizing maintenance should be adopted for anti-abrasive UHPC.

Poly(Ionic Liquid) Double-Network Elastomers with High-Impact Resistance Enhanced by Cation-π Interactions.

With the continuous development of impact protection materials, lightweight, high-impact resistance, flexibility, and controllable toughness are required. Here, tough and impact-resistant poly(ionic liquid) (PIL)/poly(hydroxyethyl acrylate) (PHEA) double-network (DN) elastomers are constructed via multiple cross-linking of polymer networks and cation-π interactions of PIL chains. Benefiting from the strong noncovalent cohesion achieved by the cation-π interactions in PIL chains, the prepared PIL DN elastomers exhibit extraordinary compressive strength (95.24 ± 2.49MPa) and toughness (55.98 ± 0.66MJ m-3) under high-velocity impact load (5000 s-1). The synthesized PIL DN elastomer combines strength and flexibility to protect fragile items from impact. This strategy provides a new research idea in the field of the next generation of safety and protective materials.