3D printing (3DP) ranks as one of the more advanced methods in the manufacturing sector. All of the industrial sectors, including automobiles, medical services, aviation, athletics, fabrics, apparel, and fashion indus...
详细信息
This study demonstrates that two-and three-dimensional spatially graded,truss-based polymeric-material metamaterials can be designed for beneficial impact mitigation and energy absorption *** a combination of numerica...
详细信息
This study demonstrates that two-and three-dimensional spatially graded,truss-based polymeric-material metamaterials can be designed for beneficial impact mitigation and energy absorption *** a combination of numerical and experimental techniques,we highlight the broad property space of periodic viscoelastic trusses,realized using 3D printing via selective laser *** beyond periodic designs,we investigate the impact response of spatially variant viscoelastic lattices in both two and three *** result reveal that introducing spatial variations in lattice topology allows for redirecting of the impact trajectory,opening new opportunities for engineering and tailoring lightweight materials with target impact *** is achieved through the combined selection of base material and metamaterial design.
Metallic nanoglasses are made of amorphous grains that are separated by lower-density amorphous boundaries,which have been proposed to enhance plasticity through the deflection of cracks and shear bands at *** has bee...
详细信息
Metallic nanoglasses are made of amorphous grains that are separated by lower-density amorphous boundaries,which have been proposed to enhance plasticity through the deflection of cracks and shear bands at *** has been difficult to experimentally control grain size and interfacial structure to understand their roles in plastic ***,we fabricate bulk nanoglasses via compaction and sintering of colloidally synthesized amorphous iron-boride *** nanoglasses have amor-phous grains with diameters from 116 nm to 576 nm and were tested using nanoindentation and mi-cropillar *** nanoglass with a grain size of 576 nm shows the highest elastic modulus and hardness of 101 GPa and 7.4 GPa,*** electron microscopy reveals that nanocrys-tals form within the nanoglasses during *** nanocrystal density correlates with higher nanoparticle crystallization enthalpy,an increase in plasticity,and a decrease in yield *** strain of 5.0%,yield strength of 3.8 GPa,and ultimate compressive strength of 2.7-3.8 GPa were *** show that the compaction of colloidal metallic glass nanoparticles results in robust bulk samples,with mechanical properties similar to that of other iron-based bulk metallic glasses.
The increasing demand for energy absorbent structures,paired with the need for more efficient use of materials in a wide range of engineering fields,has led to an extensive range of designs in the porous forms of sand...
详细信息
The increasing demand for energy absorbent structures,paired with the need for more efficient use of materials in a wide range of engineering fields,has led to an extensive range of designs in the porous forms of sandwiches,honeycomb,and *** achieve an even better performance,an ingenious solution is to learn how biological structures adjust their configurations to absorb energy without catastrophic *** this study,we have attempted to blend the shape freedom,offered by additive manufacturing techniques,with the biomimetic approach,to propose new lattice structures for energy absorbent *** this aim we have combined multiple bio-inspirational sources for the design of optimized configurations under compressive *** lattice structures are fabricated based on the designed unit cell geometries and studied using experimental and computational *** individual effect of each bio-inspired feature has been evaluated on the energy absorbance performance of the designed *** on the design parameters of the lattices,a tuning between the strength and energy absorption could be obtained,paving the way for transition within a wide range of real-life applicative scenarios.
Adhesively Bonded Carbon Fibre Reinforced Plastic(CFRP)and titanium alloy have been extensively used as a hybrid structure in modern aircrafts due to their excellent combination of mechanical properties and chemical *...
详细信息
Adhesively Bonded Carbon Fibre Reinforced Plastic(CFRP)and titanium alloy have been extensively used as a hybrid structure in modern aircrafts due to their excellent combination of mechanical properties and chemical *** study utilised NaOH anodising method to create micro-rough titanium surfaces for enhancing adhesive bonding between titanium alloy and CFRP laminates.A special and simple technique named Resin Pre-Coating(RPC)was also employed to improve the surface wetting of anodised titanium and grinded CFRP *** influences of anodising temperature and duration on the surface morphology,wettability and adhesive bond strength were *** single lap shear test results showed that the bond strength of specimens anodised at 20℃for 15 min improved by 135.9%and 95.4%,respectively,in comparison with that of acid pickled and grinded specimens(without RPC treatment).Although increasing the anodising temperature and duration produced rougher titanium surfaces,the adhesively bonded joints were not strong enough due to relatively friable titanium oxide layers.
Bio-inspired fibrillar adhesives have received worldwide attention but their potentials have been limited by a trade-off between adhesion strength and adhesion switchability, and a size scale effect that restricts the...
详细信息
Bio-inspired fibrillar adhesives have received worldwide attention but their potentials have been limited by a trade-off between adhesion strength and adhesion switchability, and a size scale effect that restricts the fibrils to micro/nanoscales. Here, we report a class of adhesive fibrils that achieve unprecedented adhesion strength(~2 MPa), switchability(~2000), and scalability(up to millimeter-scale at the single fibril level),by leveraging the rubber-to-glass(R2G) transition in shape memory polymers(SMPs). Moreover, R2G SMP fibrillar adhesive arrays exhibit a switchability of >1000(with the aid of controlled buckling) and an adhesion efficiency of 57.8%, with apparent contact area scalable to 1000 mm2, outperforming existing fibrillar adhesives. We further demonstrate that the SMP fibrillar adhesives can be used as soft grippers and reusable superglue devices that are capable of holding and releasing heavy objects >2000 times of their own weight. These findings represent significant advances in smart fibrillar adhesives for numerous applications,especially those involving high-payload scenarios.
In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal *** synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a graphen...
详细信息
In this study,a novel lubricant additive nitrogen-doped carbon quantum dot(N-CQD)nanoparticle was prepared by the solvothermal *** synthesized spherical N-CQD nanoparticles in the diameter of about 10 nm had a graphene oxide(GO)-like structure with various oxygen(O)-and nitrogen(N)-containing functional *** N-CQDs were added to MoS_(2)nanofluid,and the tribological properties for steel/steel friction pairs were evaluated using a pin-on-disk ***-equilibrium molecular dynamics(NEMD)simulations for the friction system with MoS_(2)or MoS_(2)+N-CQD nanoparticles were also *** results showed that friction processes with MoS_(2)+N-CQD nanofluids were under the mixed lubrication *** MoS_(2)nanofluid containing 0.4 wt%N-CQDs could achieve 30.4%and 31.0%reduction in the friction coefficient and wear rate,respectively,compared to those without *** analyzing the worn surface topography and chemical compositions,the excellent lubrication performance resulted from the formation of tribochemistry-induced *** average thickness of tribofilm was about 13.9 nm,and it was composed of amorphous substances,ultrafine crystalline nanoparticles,and self-lubricating FeSO_(4)/Fe2(SO_(4))_(3).NEMD simulation results indicated the interaction between S atoms in MoS_(2)as well as these O-and N-containing functional groups in N-CQDs with steel surfaces enhanced the stability and strength of *** the metal surface was further protected from friction and wear.
Thermal barrier coatings(TBC)on superalloy blade/vane enable an increase in turbine inlet temperature(TIT)and aero-engine ***,the deposition of dust on TBC significantly ablates superalloys and becomes a bottleneck fo...
详细信息
Thermal barrier coatings(TBC)on superalloy blade/vane enable an increase in turbine inlet temperature(TIT)and aero-engine ***,the deposition of dust on TBC significantly ablates superalloys and becomes a bottleneck for advanced engine *** paper presents a comprehensive mod-eling approach,based on an experiment involving dust deposition on a TBC-coated substrate,aimed at understanding the fundamental cause of substrate *** results show that a significant increase in surface roughness is obtained experimentally with dust *** temperature field within the TBC-substrate system is disturbed by surface ***,the film cooling is seriously *** the dust accumulated on the TBC surface also contributes to heat insulation by increas-ing the effective TBC thickness,localized overheating of the substrate occurs and then leads to ablation and premature failure of the *** elucidation of the overheating mechanism could inform the development of strategies to resist dust accumulation in advanced aero engines.
Image-based micromechanical models,necessary for the development of structure-property-response relations,are far from mature for complex microstructures with multi-modal distributions of morphological and crystallogr...
详细信息
Image-based micromechanical models,necessary for the development of structure-property-response relations,are far from mature for complex microstructures with multi-modal distributions of morphological and crystallographic features,such as those occurring with cold spray-formed(CSF)aluminum *** materials have a bimodal polycrystalline microstructure composed of recrystallized ultra-fine grains(UFGs)and deformed coarse grains(CGs)within prior particles.A prime reason is the lack of robust approaches for generating statistically equivalent virtual microstructures(SEVM)capturing the statistics of characteristic morphological and crystallographic features,such as grain size,crystallographic orientations,and *** paper introduces an approach,strategically integrating Generative Adversarial Network-based approaches for producing bimodal CSF AA7050 alloy microstructures,with the synthetic microstructure builder Dream3D for packing prior particles with CGs having statistically equivalent morphological and crystallographic descriptors to electron backscatter diffraction(EBSD)*** efficient finite element(FE)simulation approach is developed for the SEVMs to generate local and overall response functions through the creation of sub-volume elements(SVEs).
Recently, Cu-substituted lead apatite LK-99 was reported to have room-temperature ambient-pressure superconductivity. Here, we utilize density functional theory total energy and harmonic phonon calculations to investi...
详细信息
暂无评论