Design Of Laminated Structures Research Articles

High piezoelectric performance and resistivity through a laminated structure design for BiFeO3–BaTiO3 ceramic

BiFeO3–BaTiO3 (BF–BT) ceramics with high Curie temperature and excellent piezoelectric coefficient are expected to be applied in high-temperature piezoelectric sensors and actuators. However, its resistivity decreases rapidly with temperature and impedes its further applications. Moreover, normal methods such as doping modification cannot address this issue. In the present work, bismuth layered Bi4Ti2.93(Zn1/3Nb2/3)0.07O12 (BIT) and perovskite 0.36BiScO3-0.64PbTiO3 (BSPT) ceramics were selected as insulating layers and were, respectively, sintered with 0.7BF–0.3BT ceramics to form laminated ceramics. The heterojunction structures effectively prevent carrier migration, and both resistivities of BIT and BSPT laminated ceramics were increased from 106 to 108−9 Ω cm at 300 °C. In addition, piezoelectric properties of the BSPT-type laminated ceramics are much higher than that of BF–BT ceramics, in which the bipolar strain was increased from 0.04% to 0.1% (4 kV/mm), and d33 was increased from 140 to 237 pC/N. Therefore, designing the insulating layer may be an effective method to realize the high-temperature application for BF–BT ceramics.

Strong and tough glass composites with a partially segmented micro-architecture

Inspired by the composition of “hard” fin rays and “soft” collagen and the non-segmented and segmented composite structure of fish fins, we propose a partially segmented laminated structure design concept to overcome the brittleness of hard materials. Here, laminated glass composites with a partially segmented micro-architecture are fabricated using a laser engraving approach and a mechanical evaluation of the structure is performed. It is found that the involvement of segmentation enables an incremental cracking mechanism by restraining cracks in segments and a tablet sliding mechanism, thereby producing an unusual combination of strength and toughness. The strength of the partially segmented glass composite is controlled by the depth of segmentation, while the enhancement of toughness is controlled by a superposition of the cracking and sliding mechanisms. The balanced zone involving these mechanisms enables simultaneous improvement of strength and toughness. Additionally, the strength and toughness of partially segmented glass composite can be tuned by varying segment thickness and changing the interlayer materials.

Atomic/Molecular Layer-Deposited Laminated Li2O-Lithicone Interfaces Enabling High-Performance Silicon Anodes.

Silicon-based materials are of long-standing interest as the anodes for next-generation lithium-ion batteries, yet their low initial Coulombic efficiency and poor interfacial stability are lethal limitations. In this work, we used atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques to fabricate a lithium-containing laminated Li2O-lithicone hybrid film (∼5 nm) on a silicon electrode. The laminated film provides an additional surface Li source around silicon cores, which can partially reimburse the Li loss during battery cycling. Characterization of interfacial components shows that such a laminated Li2O-lithicone interface undergoes gentle element changes and participates in a hybrid solid electrolyte interphase with Li2CO3, Li2O, LixPOFy, and LiF species. Finite element model analysis and morphology characterization demonstrate that the laminated structure design can help relieve the interfacial stress and thus retain the integrity and reactivity of the silicon composite anode during cycling. Moreover, the lithium-based laminated film leads to a fast Li+ migration kinetics on the surface of the electrode as revealed by the galvanostatic intermittent titration technique and density functional theory calculation. Benefiting from the above merits, a silicon anode with a 91.2% initial Coulombic efficiency, a rate performance of 1460 mA h g-1 at 2 A g-1, and a reversible capacity over 646 mA h g-1 after 850 cycles was achieved. This work exemplifies the advantages of lithium-based hybrid films precisely engineered by ALD/MLD techniques for improving performances of advanced silicon anode batteries and deepens understandings on the mechanism of interfacial stability and reaction kinetics.

Improvement of SiC/PyC coating on mechanical and anti-oxidation properties through biomimetic laminated structure design

To improve fracture toughness and oxidation resistance of SiC coating, we designed and prepared a SiC/PyC laminated coating with biomimetic laminated structure on carbon/carbon (C/C) composites by chemical vapor deposition (CVD) method. The microstructure, mechanical properties and oxidation resistance of the coating were investigated. The results showed that the laminated structure could effectively improve the toughness of SiC coating and avoid the formation of penetrating cracks, thus improved the oxidation resistance of coating. The weight loss of laminated SiC/PyC coated sample decreased 75.2 % compared with that of single SiC coated sample after oxidation at 1773 K. The good oxidation resistance and mechanical properties of SiC/PyC laminated coating were attributed to the toughening effect of laminated structure including crack deflection and interface debonding. Our work could bring beneficial enlightenment to improve the toughness of ceramic coating.

Bamboo-Inspired Renewable, Lightweight, and Vibration-Damping Laminated Structural Materials for the Floor of a Railroad Car.

It is important for the floor of railroad cars to be fitted with vibration- and noise-reducing, fire-resistant, and durable materials. In this study, inspired by a delicate and ordered bamboo gradient structure and excellent multilevel interfaces, we fabricated a laminated composite with characteristics similar to those of the bamboo structure using a simple and effective "top-down" method by laminating fast-growing wood, waste rubber, and bamboo charcoal plastic sheets made of bamboo processing residues. This composite material combines the unique advantages of a laminated structure design and composite interface bionics. The low density (0.73 g/cm3) of the laminated composite results in a specific modulus of 13.03 GPa cm3/g, a vibration damping ratio of 6.61%, and an impact toughness of 14.16 J/cm2, which is significantly higher than that of other wood-based composites used for high-speed rail floors, such as Birch plywood (BP). In addition, we also investigated the laminated composite bonding property, fire resistance, and fatigue performance. This biomimetic bamboo-wood composite material has great potential for application in fitting the floor of eco-friendly railway cars.

Bicontinuous laminated structure design of polypropylene/reduced graphene oxide hybrid films for thermal management

Bicontinuous laminated structure design of polypropylene/reduced graphene oxide hybrid films for thermal management

Improvement of Sic/Pyc Coating on Mechanical and Anti-Oxidation Properties Through Biomimetic Laminated Structure Design

Improvement of Sic/Pyc Coating on Mechanical and Anti-Oxidation Properties Through Biomimetic Laminated Structure Design

Development of laminated bamboo lumber with high bond strength for structural uses by O2 plasma

To improve the reuse rate of bamboo materials, laminated bamboo lumber (LBL) with high bond strength has been developed for structural use using bamboo residues (BRs). The laminated structure design is an important factor affecting LBL performance, and thus, it is essential to study various LBL blank structures. The major direction is parallel to the panel length, and the minor direction is perpendicular to the panel length. In this study, BRs were cut into A and B units along the major and minor directions, respectively. The LBL with good performance was selected by different forming methods and modified by O2 plasma. It was found that 1) the volumeutilization rate of BRs in LBL is above 85%; 2) the wet bonding strength of LBL products is increased by 58.58% compared to ordinary plywood, when the O2 plasma modification time is 6 min and 12 min respectively, the wet bonding strength is increased by 75.69% and 76.27% compared to ordinary plywood; 3) when bamboo pieces are arranged in parallel, the modulus of rupture in the major direction is ~ 2 times greater than in the minor direction, while a staggered arrangement can effectively reduce the bamboo anisotropic effect; 4) the destruction of LBL mainly occurs at the joints; 5) after O2 plasma modification, the wettability of green bamboo and yellow bamboo was significantly improved, followed by bamboo flesh.

Improvement of CrMoN/SiNx coatings on mechanical and high temperature Tribological properties through biomimetic laminated structure design

CrMoN/SiNx multilayered coatings were fabricated by controlling the shutter-open time of two sputtering guns in a radio frequency magnetron sputtering system. Employing the structure of nacreous shells from nature, nano-crystalline and amorphous monolayers were periodically stacked. CrMoN/SiNx thin films with different bi-layer periods were deposited on Si-wafer and Inconel-718 substrates. The phases of the coatings were examined using a grazing incidence X-ray diffraction (XRD) technique. Information of chemical composition was obtained by field emission electron probe micro-analyzer (FE-EPMA). The confirmation of multilayer structure was observed by transmission electron microscope (TEM). The wear tracks were revealed by scanning electron microscope (SEM). Mechanical and high-temperature tribological properties were evaluated using a nano-indenter and a high-temperature tribometer, respectively.Grain refinement phenomenon was verified using XRD peak broadening at high angles, indicating inhibition in the column structure and the formation of an amorphous phase. CrMoN/SiNx exhibited higher high-temperature wear resistance for a specific bi-layer period, which was attributed to the multilayer strengthening mechanism. Multilayered structure provided tremendous benefit to COF improvement, which was reduced by 50% of the value of CrMoN. Simultaneously, the toughening effect of the biomimetic structure design improved the wear resistance ability of the coating. Especially, the slight amount of SiNx unpredictably enhanced the wearing properties of the system, which is in consistent with the role of chitin in nacre. Moreover, an optimal bi-layer period was identified, resulting in optimal mechanical properties that were consistent with the high-temperature tribological properties. Furthermore, the wear tracks on the specimens were analyzed through field-emission scanning electron microscopy, which support the wearing behavior alteration. Finally, a CrMoN/SiNx multilayer coating with optimal high-temperature characteristics was demonstrated in this study.

Nature-inspired nacre-like Ti6Al4V-(Ti2AlC/TiAl) laminate composites combining appropriate strength and toughness with synergy effects

Nacre, a biomimetic model system with multiscale architectures and adjustable components, has always inspired researchers to create novel materials with advantages such as light-weight, exceptional strength and toughness. Inspired by nature, nacre-like bionic Ti2AlC/TiAl–Ti6Al4V laminated composite sheets had been designed and fabricated by spark plasma sintering technology using commercial Ti6Al4V as the toughening layers and Ti–Al–TiC reaction system as the composite layers. The phase compositions and structural characteristics of the composite sheets were characterized by XRD, SEM and EDS. In addition, the mechanical properties at room temperature were also measured. The results indicated that a Ti3Al interfacial layer was formed between the composite layer and the toughening layer, meanwhile the compositions of the composite layer were composed of TiAl, Ti3Al, Ti2AlC and a small amount of TiC. It's noteworthy that the Ti2AlC/TiAl–Ti6Al4V laminated composite sheets showed a significant increase in toughness while maintaining or improving strength even with holes in the sheets, in comparison with monolithic TiAl. When the loading direction was perpendicular to the laminated structure, the flexural strength and fracture toughness of the composite sheet with 20 wt% Ti2AlC reached good comprehensive values, which were up to 564.86 MPa and 39.15 MPa m1/2, respectively. The particles-reinforced composite layers and laminated structure design not only affected the crack propagation, but also cooperated with each other leading to a complex deflection and expansion behavior, which consumed the fracture energy and improved the overall mechanical properties of the composite sheets.

Effect of laminated structure design on physical and mechanical properties of laminated bamboo sliver lumber

Laminated structure design is one of the significant factors that affect the physical and mechanical properties of laminated bamboo sliver lumber (LBSL). Eight patterns of assembly for 5-ply LBSL (LLLLL, LLVLL, LVLVL, LVVVL, LLV’LL, LV’LV’L, LVV’VL, and LV’VV’L) were prepared in this study; L represents one horizontal layer of the bamboo-sliver veneer, V represents the layer that is vertical to L, and V’ represents the layer at an angle of 45 ° to the L (or V). The objective of this study was to investigate the exclusive effect of the laminated structure design on the performance of the LBSL, rather than the multiple effect of the number of plies, chemical components, matter content, etc. The results indicated that the bending modulus of elasticity (MOE), bending modulus of rupture (MOR), impact strength, tensile strength, and compressive strength decreased with the decrease in number of layers of ply, for the following levels of L-ply: 5-L-ply (LLLLL), 4-L-ply (LLVLL, and LLV’LL), 3-L-ply (LVLVL, and LV’LV’L), and 2-L-ply (LVVVL, LVV’VL, and LV’VV’L). For the LBSL with the same number of L layers, those which had more V’ layers possessed better properties, due to the action of the parallel component of the force of the V’ layer. The values of absorption swelling rate, breaking strength, and displacement indicated that the LBSL with higher structural complexity achieved poorer underwater dimensional stability, but better single-bolted connection performance.

Stochastic optimization of graphite-flax/epoxy hybrid laminated composite for maximum fundamental frequency and minimum cost

Ecological approach in automotive, aerospace and marine industries have stated that natural fibers (especially flax) can be used as alternative reinforcing materials to glass fibers because of their inherent good vibration and cost performances. In this regard, the present paper is an attempt to show the usage of flax fiber as an alternative to E-glass in interply hybrid composite structures in terms of fundamental frequency and cost. Stacking sequences design and optimization of laminated composites based on Differential Evolution (DE), Nelder Mead (NM) and Simulated Annealing (SA) algorithms are considered. The optimization problem is to find the number of high stiffness and less expensive laminates maximizing the fundamental frequency and minimizing the cost by multi objective optimization approach. The results show that the proposed optimum graphite-flax/epoxy interply composite structure give better than the result of graphite-glass/epoxy in terms of maximum fundamental frequency and minimum cost. It is also found that DE, NM and SA algorithms show comparable performance versus Ant Colony Optimization (ACO) for the same laminated structure design problems.

Laminated structure design of wood—Bamboo hybrid laminated composite using finite element simulations

In order to explore competitive bio-products to meet the requirements of the engineering structural member with high-strength, light-weight and low cost, bamboo bundle and wood laminated veneer lumbers (BWLVLs) with well-designed laminated structures have been regarded as potential candidate. Eight different assemble patterns of BWLVLs were designed and their mechanical performances with elastic range and ultimate bearing failure stage including the deflection, stress distribution, and stress transferring between adjacent layers were investigated using finite element simulations. The results showed that the finite element predicting model with a high accuracy could be used to optimize the design of laminated structures for bamboo bundle and wood veneer laminated composites. The relative error of the simulation results from the predicting model and the experimental results for different laminated composite panels was substantially less than 10%. The rank order for the VonMises stress of eight assemble BWLVLs were (7B) > (BBPPPBB) ≈ (BBPBPBB) > (BPBPBPB) > (BPPPPPB) ≈ (BPPBPPB) > (PBPBPBP) > (7P), (P) poplar, and (B) bamboo. The stress in laminated composites was transferred from poplar layers with low modulus to bamboo bundle layer with high elastic modulus.

Effect of laminated structure design on the mechanical properties of bamboo-wood hybrid laminated veneer lumber

The effects of veneer orientation and loading direction on the mechanical properties of bamboo-bundle/poplar veneer laminated veneer lumber (BWLVL) were investigated by a statistical analysis method. Eight types of laminated structure were designed for the BWLVL aiming to explore the feasibility of manufacturing high-performance bamboo-based composites. A specific type of bamboo species named Cizhu bamboo (Neosinocalamus affinis) with a thickness of 6 mm and diameter of 65 mm was used. The wood veneers were from fast-growing poplar tree (Populus ussuriensis Kom.) in China. The bamboo bundles were obtained by a mechanical process. They were then formed into uniform veneers using a one-piece veneer technology. Bamboo bundle and poplar veneer were immersed in water-soluble phenol formaldehyde (PF) resin with low molecular weight for 7 min and dried to MC of 8–12 % under the ambient environment. All specimens were prepared through hand lay-up using compressing molding method. The density and mechanical properties including modulus of elasticity (MOE), modulus of rupture (MOR), and shearing strength (SS) of samples were characterized under loading parallel and perpendicular to the glue line. The results indicated that as the contribution of bamboo bundle increased in laminated structure, especially laminated on the surface layers, the MOE, MOR and SS increased. A lay-up BBPBPBB (B-bamboo, P-poplar) had the highest properties due to the cooperation of bamboo bundle and poplar veneer. A higher value of MOE and MOR was found for the perpendicular loading test than that for the parallel test, while a slightly higher SS was observed parallel to the glue line compared with perpendicular loading. Any lay-up within the homogeneous group can be used to replace others for obtaining the same mechanical properties in applications. These findings suggested that the laminated structure with high stiffness laid-up on the surface layers could improve the performance of natural fiber reinforced composites.

Enhanced fracture toughness of TiBw/Ti3Al composites with a layered reinforcement distribution

The prospect of combining laminated structure design and tailored reinforcement distribution to toughen brittle materials is investigated. TiBw/Ti3Al–Ti3Al laminated composites consisting of alternating TiBw/Ti3Al and Ti3Al layers were fabricated by reaction annealing of stacked, alternating foils of TiBw/Ti and Al. Enhancement in the fracture toughness is experimentally observed, which is attributed to stress redistribution and stress state change in laminated composites. Theoretical prediction of fracture toughness depending on a shear ligament toughening model agrees well with the experimental value. It is expected that the design strategy can be extended to other brittle intermetallic compounds, such as Ni–Al, Fe–Al, and Nb–Al systems.

Fabrication and mechanical properties of laminated HfC–SiC/BN ceramics

Laminated HfC–SiC/BN ceramics were successfully fabricated by tape casting and hot pressing. Fully dense HfC–SiC ultra-high temperature ceramics with homogeneous structure were obtained. The introduction of the weak BN layer resulted in a slight decrease of the flexural strength but significantly improved the fracture toughness compared with monolithic HfC–SiC ceramics. The fracture toughness of laminated HfC–SiC/BN ceramics in the parallel direction peaked at 8.06 ± 0.46 MPa m1/2, which increased by 115% than that of monolithic HfC–SiC ceramics. The composites showed non-catastrophic fracture behaviors in both parallel and perpendicular directions. It indicates that laminated structure design is a promising approach to obtain full density HfC–SiC ceramics with high fracture toughness.

Producing laminated NiAl with bimodal distribution of grain size by solid–liquid reaction treatment

The prospect of combining laminated structure design and grain size tailoring to toughen brittle materials is examined. Laminated NiAl consisting of coarse-grained layers and fine-grained layers was fabricated by solid–liquid reaction treatment of stacking Ni and Al foils. The fracture toughness at ambient temperature has been improved 2–3 times. It is of great potential to extend this approach to other binary alloys, such as Ti–Al, Fe–Al, Nb–Al, etc., where solid–liquid reaction occurs readily at high temperature.

Compaction of mechanically milled pure nanocrystalline tungsten : E.Ivanov, C.E.Wickersham. (Tosoh SMD, Inc, Grove City, Ohio, USA.)

The prospect of combining laminated structure design and grain size tailoring to toughen brittle materials is examined. Laminated NiAl consisting of coarse-grained layers and fine-grained layers was fabricated by solid–liquid reaction treatment of stacking Ni and Al foils. The fracture toughness at ambient temperature has been improved 2–3 times. It is of great potential to extend this approach to other binary alloys, such as Ti–Al, Fe–Al, Nb–Al, etc., where solid–liquid reaction occurs readily at high temperature.