Light Weight Research Articles

Design of a two-seater seaplane wing spar structure with composite materials

A two-seater, mono-wing seaplane was initially developed for survey and rescue operations, with an empty weight of 470 kg and a maximum takeoff weight of 650 kg. Fiber-reinforced composite materials, consisting of fiber reinforcement and thermosetting polymer, were used in this airframe to reduce weight because the structural properties can be customized by adjusting the orientation of the fiber fabric layup and removing redundant material, which is impossible with metal. This paper presents a comprehensive overview of the design process for the aircraft's primary I-beam wing spar, employing composite material. Before conducting design calculations, it is critical to consider the variability of characteristics of composite materials caused by fabrication conditions such as temperature, humidity, and defects. As a result, it is imperative to conduct thorough testing of carbon fiber-reinforced composites following many different testing requirements. The coupon tests capture critical characteristics such as strength, stiffness, and Poisson's ratio across several orientations. The wing spar I-beam structure was subsequently developed with three primary considerations: stiffness (maximum deflection), strength, and stability (structural buckling). Following preliminary sizing of the I-beam wing spar, a simple initial layup was recommended, with primary loading in each component. The initial design was then subjected to a more detailed calculation using classical lamination theory, which took into account distributed load along the wing, spar taper, ply-drops along the span, and composite layup guidelines in order to reduce structural weight while ensuring the main spar's ability to withstand operational loads effectively. The calculating results show that the spar with an optimized composite design has a lighter weight than the original design by around 43%, while it can withstand the same loads with no analytical failure.

Novel orientation relationships and mechanical properties of in situ synthesized Ti5Si3-reinforced TiAl composite via electron beam-directed energy deposition

Titanium aluminide (TiAl) alloys, known for their light weight and high specific strength, hold promising potential for aerospace applications. Recent studies have focused on improving their properties through composite strengthening. An in situ synthesized Ti5Si3-reinforced TiAl composite with excellent performance was successfully fabricated via a dual-wire electron beam-directed energy deposition (EB-DED) process. The microstructure of the as-deposited Ti5Si3/TiAl composite consisted of primary Ti5Si3 rods, eutectic Ti5Si3 needles, and lamellar TiAl+Ti3Al structures. The phase transformation during the EB-DED process was L→Ti5Si3+L→Ti5Si3+(α+Ti5Si3)Eutectic→Ti5Si3+(Ti3Al+TiAl)Eutectoid. The expanded Blackburn orientation relationships among the ternary phases emerged from the eutectic reaction of L→α+Ti5Si3 with an undercooling exceeding 136°C and the subsequent eutectoid reaction with ordering transformation and were expressed as <112¯0>Ti3Al//<101¯0>Ti5Si3//<11¯0]TiAl and {0001}Ti3Al//{0001}Ti5Si3//{111}TiAl. The Ti5Si3 phase had a greater hardness than did the lamellar structures and enhanced the mechanical properties of the matrix. The compressive yield strengths at room temperature and 750°C were 1221±51 and 1034±34 MPa, respectively, whereas the tensile yield strength was 347.4±12.7 MPa at 950°C, surpassing those of other TiAl alloys. The calculated strength with different strengthening mechanisms was 1056.4 MPa, and the greatest improvement in strength was attributed to the decreased interlamellar spacing. This work provides critical insight into the design of TiAl composites with superior mechanical properties and aids in understanding the microstructural evolution of as-deposited Ti5Si3/TiAl composites.

Lightweight, thermally insulating SiBCN/Al2O3 ceramic aerogel with enhanced high-temperature resistance and electromagnetic wave absorption performance

Owing to tunable dielectric properties, light weight and high porosity, polymer-derived SiBCN ceramic aerogels possess significant application prospects in electromagnetic wave (EMW) absorption and thermal insulation. However, due to inadequate oxidation resistance, the structural collapse and performance deterioration of SiBCN aerogels will easily occur in high-temperature aerobic environments, limiting their application. Herein, to address this issue, a novel and straightforward strategy based on typical polymer-derived-ceramic (PDC) aerogel method and impregnation with boehmite sol was proposed for synthesizing SiBCN/Al2O3 composite ceramic aerogels. The microstructure, phase composition, thermal insulation, oxidation resistance and EMW absorption properties of SiBCN/Al2O3 ceramic aerogels were investigated. The resulting SiBCN/Al2O3 composite aerogel demonstrates superior high-temperature structural stability, exhibiting an ultra-low linear shrinkage of only 6.5 % following heat treatment at 1200 °C for 2 h in air. Additionally, the composite aerogel shows a low thermal conductivity of 0.039 W/mK and a low density of 0.112 g/cm3. The SiBCN/Al2O3 composite aerogel, composed of dielectric SiBCN, conductive free carbon, and insulating alumina, demonstrates outstanding EMW absorption properties with a minimum reflection loss of −48.6 dB and an effective bandwidth of 5.8 GHz. The enhanced microwave absorption performance is mainly attributed to the improved impedance matching, multiple reflection, and enhanced interfacial polarization resulting from the introduction of Al2O3. Given prominent oxidation resistance, thermal insulation and EMW absorption properties, the SiBCN/Al2O3 composite aerogel paves the way for developing microwave absorption and thermal insulation integrated material in high-speed vehicles.

Enhanced piezoelectricity of P(VDF-TrFE) by BN nanosheets doping and leading to high performance laminated magnetoelectric composites

With the development trend of miniaturization, lightweight and portability of electronic equipment, piezoelectric devices have been widely applied to transducers, sensors and energy harvesters. Piezoelectric polymers, like poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), possess the advantages of light weight, good flexibility, and simple preparation methods. However, P(VDF-TrFE) films is not entirely composed of piezoelectric phase (β phase), so increasing the content of β-phase is very important for the piezoelectric property of P(VDF-TrFE) films. Doping nanomaterials with unique properties has been proved to be a feasible way to increase the content of β-phase. In this paper, hexagonal boron nitride (h-BN) nanosheets, a kind of 2-dimensional van der Waals materials with wide bandgap, as filler were doping into poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) piezoelectric films by solution casting method. The composite films as designed, in which h-BN nanosheets were uniformly dispersed in P(VDF-TrFE), achieved higher contents of piezoelectric phase (β phase). Compared with pure P(VDF-TrFE) films, the optimal P(VDF-TrFE)/BN piezoelectric film achieved a much higher piezoelectric coefficient (d33) (∼42 pC/N), also leading to a higher piezoelectric voltage output than that of pure P(VDF-TrFE). By laminating the P(VDF-TrFE)/BN films as designed with FeSiB Metglas, high magnetoelectric voltage coefficients under zero and low DC magnetic bias were achieved. In summary, this paper presents a feasible and potential method for improving PVDF piezoelectricity, which has been successfully applied in high performance magnetoelectric devices.

Study on Ice Temperature Fields and Borehole Closure Rates During Thermal Ice Drilling

Thermal ice drilling technology is extensively used in drilling operations such as temperature measurement holes and subglacial water environment investigations in Antarctica owing to its advantages of compactness, light weight, and ease of operation. However, thermal drilling disturbs the initial temperature of the surrounding ice, making it impossible to obtain the true ice temperature through a borehole within a short period. Meltwater refreezing also causes the borehole to shrink and close, posing a threat to drilling safety. Therefore, obtaining an accurate characterization of the temperature field around the hole and assessing the meltwater refreezing rate are crucial for determining the appropriate temperature measurement duration and optimizing drilling parameters. To address this issue, a temperature measurement platform for the ice surrounding the borehole was developed. Experimental investigations were conducted to analyze the temperature fields during thermal drilling using both small-diameter thermal heads and RECoverable Autonomous Sonde (RECAS) thermal heads. This study clarifies the temperature field changes in the surrounding ice during and after thermal drilling. It also elucidates the effects of parameters such as the ice temperature, thermal head heating power, and thermal head diameter on the temperature field around the hole and estimates the meltwater refreezing rate inside the borehole. The results indicated that the temperature of the surrounding ice peaked approximately 5–7 h after drilling and subsequently decreased and returned to the original temperature within 48 h. The thermal disturbance radius in the surrounding ice was approximately 1.1 to 1.7 times the borehole radius when the thermal head passed through. However, after the thermal head passed, the thermal disturbance radius continued to expand owing to the heat released from meltwater refreezing, reaching 9.7 to 12.5 times the borehole radius. The average meltwater refreezing rate, estimated from temperature measurement tests at −16 °C, was 3.6 mm/h.

Kinetic Process of Graphene Growth from Dual‐Carbon Sources on Alpha Alumina

AbstractAs a new member of the super graphene‐skinned materials family, graphene‐skinned alumina material integrates the excellent characteristics of graphene and alumina, with characteristics like high electrical conductivity and thermal conductivity, light weight, and has broad application prospects in integrated circuits, electric heating, wind power deicing. Based on density functional theory, the cracking, migration of major carbon species, nucleation, and edge growth of ethylene and acetylene on the α‐Al2O3(0001) plane are investigated. The results show that: 1) α‐Al2O3 substrate has metal‐like catalytic activity, the pyrolysis products of C2H2 and C2H4 carbon sources are C2H and C2H2, respectively, and the main active species on the substrate surface are C2H; 2) The adsorption properties and nucleation rate of C2H on the substrate surface are better than C2H2, but C2H is more difficult to migrate than C2H2, and their migration energy barriers are 2.80/0.88 eV, respectively; 3) The microscopic mechanism of the preparation of graphene‐skinned alumina materials by dual‐carbon sources is that: the dual‐carbon sources are cracked into C2H and C2H2, then C2H nucleates to form graphene nuclei on the substrate surface, finally C2H2 participates in the edge growth of graphene on the substrate, and the AC(Armchair) edge growth rate is faster.

Preparation of carboxylated-silk nanofibers by the one-pot method of maleic acid hydrolysis.

In this study, a maleic acid (MA) hydrolysis one-pot method is proposed to prepare carboxylated silk nanofibers (MA-SNFs). The MA concentration, hydrolysis temperature, and processing time were optimized. Combined with high-pressure homogenization, MA-SNFs with a carboxyl content of 0.617±0.019mmol/g and length of 333±116nm were obtained with a yield of 54.90±1.98% at the optimal conditions: 50wt% of MA concentration, 110°C of hydrolysis temperature and 120min of processing time. The morphology, chemical structure, and crystal structure of raw silk fibroin (SF), acid-hydrolyzed silk fibroin and nanofibers were studied. Furthermore, MA was reused several times with a recovery rate of >94% and maintained almost the same treatment effect. Finally, due to the presence of carboxyl groups, MA-SNF hydrogels were successfully prepared by an acetic coagulation vapor bath which exhibited excellent self-supporting ability and mechanical properties as well as a more sensitive pH response compared with regenerated silk fibroin solution and other non-carboxylated silk nanofibers. The MA-SNF aerogels had the characteristics of light weight, high strength and porous with cross-linked nanostructures.

Research on the Performance of Carbon Fiber Composite Railings for Ships

With the development of the shipbuilding industry, the requirements for the safety and corrosion resistance of ship structural components are becoming increasingly high. Most of the components used in traditional ships are made of steel, which cannot meet the requirements of corrosion resistance and safety for existing ships. In order to improve the structural safety and corrosion resistance of ship railings, as well as their lightweight requirements, this article proposes a lightweight design for ship railing structures based on the advantages of carbon fiber composite materials, such as light weight, high strength, and high modulus, on the basis of the existing traditional metal railing structures for ships. Based on the anisotropy of carbon fiber composite fibers, the characteristics of overlapping/weaving structures, and the influence of the interface between carbon fiber composite materials and metal materials on the strength of ship railing structures, a finite element simulation model of carbon fiber composite materials is established. By setting constraints such as volume fraction, stress, strain, displacement,etc.in the given simulation model, the layout of materials in the optimization results is used to guide the design of the structure, and the size parameters of the ship railing barrel are optimized for structural optimization. Thus achieving lightweight design of ship railings and meeting the requirements for lightweight, safety, service life, and corrosion resistance of ship structural components.

Mesoscopic simulation study on density gradient metallic foam sandwich panels under hypervelocity impact

The high stiffness of sandwich panel shield ensures the survival of satellites and spacecrafts, making them extensively utilized in practical aerospace engineering. Metallic foams are exceptionally appropriate for spacecraft debris shields owing to their light weight and superior energy absorption characteristics. The internal mesostructure of a metallic foam plays a crucial role in determining its protective performance. At the mesoscale, the density gradient metallic foam exhibits a greater potential for protection compared to uniform metallic foam under hypervelocity impact. Therefore, this study investigates the behavior of density-gradient foams under hypervelocity impact. By leveraging three-dimensional Voronoi tessellation in conjunction with the background mesh-mapping algorithm, this study constructed mesoscopic finite element models of the layered and continuous-density gradient metallic foam, considering the internal structure of randomness. Subsequently, the Finite Element-Smoothed Particle Hydrodynamics (FE-SPH) adaptive method in LS-DYNA was employed to conduct numerical simulations of the hypervelocity impact. First, the simulation was validated through a comparison with the experiment. Based on the results of the numerical simulations, the characteristics of the debris cloud and the damage within the foam were analyzed. It was determined that the protection mechanism of the density gradient foam sandwich panel under hypervelocity impact involved a coupling effect between the domino and microchannel effects. The different damage characteristics of layered density gradient foam sandwich panels were analyzed. According to this mechanism, foam sandwich panels with different density-gradient configurations were designed and their protective performances were compared to determine the optimal density-gradient configuration to provide valuable insights into the optimal design of protective structures.

Structural-Functional Integrated Graphene-Skinned Aramid Fibers for Electromagnetic Interference Shielding.

Structural-functional integrated polymer fibers with exciting properties are increasingly important for next-generation technologies. Herein, we report the structural-functional integrated graphene-skinned aramid fiber (GRAF) featuring high conductivity, high strength, and light weight, which is weaved for efficient electromagnetic interference (EMI) shielding. Graphene was self-assembled onto the surface of aramid fibers through a dip-coating strategy using an aramid polyanion (APA) as the binder and the etchant. The molecular dynamics (MD) simulation results show that the binding energy of the APA-modified aramid chain and graphene (1.3 J/m2) is superior to that of the aramid chain and graphene (0.2 J/m2). The APA has a higher surface energy (55.2 mJ/m2) and can etch the fiber surface, forming grooves, which enables effective adsorption and self-assembly of graphene onto the fiber surface. The GRAF exhibits a high conductivity of 1062.04 ± 116.78 S/m, along with excellent strength (4.66 ± 0.16 GPa) and modulus (106.33 ± 8.21 GPa), outperforming most reported conductive composite fibers (e.g., natural fibers, polymer-based fibers, inorganic fibers, etc.). The weaved functional fabric using the structural-functional integrated GRAF shows an EMI shielding efficiency (SE) of up to 67.86 dB in the X-band and can rapidly heat up to 200 °C within 40 s at 12 V voltage. In addition, the GRAF fabric can maintain its electrical conductivity after a long-term washing, showing excellent washing resistance. This study demonstrates an effective method to fabricate structural-functional integrated materials and shows the promise of carbonene fibers for EMI shielding.

Launching Graphene into 3D Space: Symmetry, Topology, and Strategies for Bottom-Up Synthesis of Schwarzites.

Schwarzites are hypothetical carbon allotropes in the form of a continuous negatively curved surface with three-dimensional periodicity. These materials of the future attract interest because of their anticipated large surface area per volume, high porosity, tunable electric conductivity, and excellent mechanical strength combined with light weight. A three-decade-long history attempting schwarzite synthesis from gas-phase carbon atoms went without success. Design of schwarzites is both a digital art and the science of placing tiles of sp2-carbon polygons on mathematically defined triply periodic minimal surfaces. The knowledge of how to connect polygons in sequence using the rules of symmetry unlocks paths for the bottom-up synthesis of schwarzites by organic chemistry methods. Schwarzite tiling by heptagons is systematically analyzed and classified by symmetry and topology. For the first time, complete plans for the bottom-up synthesis of many schwarzites are demonstrated. A trimer of heptagons is suggested as the key building block for most synthetic schemes.

Three-channel-switchable coded aperture snapshot multispectral polarization imaging.

An ingenious and compact snapshot multispectral polarization imaging method is proposed based on a new, to the best of our knowledge, three-channel-switchable spectral polarization coded aperture. We utilize the coded aperture to simultaneously select three-channel light components and encode them with specific spectrum-polarization coefficients. It enables easy retrieval of each channel's light component from the mixed information via polarization measurements and linear decoding operations. Distinct three-channel light components can be detected simultaneously, thus achieving either three spectral images or linearly polarized ones per snapshot. The number of detectable light components is unlimited and triple that of snapshot times, showing its superior capability in measuring spectral polarization properties. The resulting prototype is miniaturized, featuring compact dimensions of Φ5.5 cm × 25 cm and a light weight of ∼800 g. This is attributed to its simplistic structure comprising a monochrome polarization detector and an imaging lens integrated with the coded aperture, making it suitable for portable and on-board applications. Furthermore, the absence of advanced or costly production technologies for manufacturing the prototype ensures an affordable price for its acquisition, facilitating widespread adoption and application of the proposed method.

Refined finite element analysis of helical wire ropes under multi-axial dynamic loading

Due to high tensile strength, light weight, and good flexibility, the steel wire ropes with helical structures are widely used as crucial load-bearing components in various industrial sectors such as civil engineering. They are subjected to significant vibrations caused by multi-axial dynamic loading during the service period which may eventually result in premature failures. This paper presents a refined finite element analysis method for helical wire ropes under multi-axial dynamic loading. The proposed method employs multi-directional dynamic excitations extracted from the analysis of the overall engineering systems to consider actual loading conditions. Refined finite element analysis of the entire steel wire rope under multi-axial dynamic loading is carried out for the first time based on the global-local finite element model to obtain detailed mechanical responses. The critical rope segment is represented by solid elements taking into account the helical structure, inter-wire frictional contact, slippage, and material nonlinearity, among others, and non-critical segments are simulated with beam elements in the established global-local model, which can achieve good balance between computational efficiency and accuracy. The refined finite element modeling strategy is validated via three numerical examples with comparisons against the results in the literature. The proposed method is illustrated on the suspender cable used in suspension bridges. Detailed mechanical responses and their influencing factors are examined to acquire new insights into the dynamic mechanical characteristics of typical double-helical wire rope. The present work can provide an efficient tool for the assessment of in-service engineering systems containing helical wire ropes.

The Impact of Reinforcement Ratio on the Punching Shear of CFRP Grid-Reinforced Concrete Two-Way Slabs.

Corrosion of steel reinforcement in concrete slabs undermines structural durability and shortens the lifespan of concrete structures. Carbon Fiber-Reinforced Polymer (CFRP) is a promising material offering benefits such as high strength, corrosion resistance, and light weight. This study aims to investigate the punching shear performance of concrete slabs reinforced with CFRP grids, focusing on the effects of different reinforcement ratios. A series of experiments were conducted on two-way concrete slabs reinforced solely with CFRP grids to assess their punching shear resistance. Experimental results show that the CFRP grid achieves an ultimate tensile strength of 2181 MPa, with the cracking load of CFRP grid-reinforced slabs reaching approximately 20% of the ultimate load, highlighting a strong correlation between the ultimate load and grid reinforcement ratio. The observed punching failure exhibited clear brittle characteristics, characterized by the formation of radial and circumferential cracks on the tensile surface of the slab. The reinforcement ratio significantly influences the failure mode of the slabs; as the reinforcement ratio increases, the ultimate punching loads also increase. Additionally, a mathematical formula is proposed to predict the punching bearing capacity, achieving calculation errors below 20%. These findings contribute valuable insights into using CFRP grids as primary reinforcement, enhancing the design and application of durable concrete slab structures.

The High-Strain-Rate Impacts Behaviors of Bilayer TC4-(GNPs/TC4) Composites with a Hierarchical Microstructure.

Ti matrix composites (TMCs) are promising structural materials that meet the increasing demands for light weight the automobile and aircraft industries. However, the room temperature brittleness in the traditionally homogeneous reinforcement distribution of TMCs limits their application in high-strain-rate impact environments. In the present study, novel bilayer TMCs with hierarchical microstructures were designed by the laminated combination of graphene nanoplatelet (GNPs) reinforced TC4 (Ti-6Al-4V) composites (GNPs/TC4) and a monolithic TC4. Meanwhile, the configuration of the microstructure, impact performance V50, and deformation modes of the bilayered TC4-(GNPs/TC4) plate was investigated. The plates were fabricated via field-assisted sintering technology (FAST). It turned out that the TC4-(GNPs/TC4) plate with a 7.5 mm thickness against a 7.62 mm projectile exhibited greater impact performance (V50~825 m/s) compared to the TC4 and GNPs/TC4 single-layer plates. The plate failure modes were dependent on the microstructure while the failure behaviors seemed to be influenced by the hierarchical configuration. This work provided a new strategy for utilizing TMCs in the field of high-strain-rate impact environments.

Analysis of successful and unsuccessful snatch and clean and jerk lifts in IWF World Championships (2011–2023)

In this research, male and female athletes who won gold, silverand bronze medals at the International Weightlifting Federation Senior World Championship (between 2011 and 2023); (a) analysis of successful and unsuccessful lifts in snatch and clean and jerk techniques, (b) analysis of successful and unsuccessful lifts in 3 lift attempts in both techniques and, (c) It is aimed to investigate the lifting attempts of athletes that determine their medal rankings in snatch, clean and jerk and total. In this retrospective study, data of 3144 (1603 and 1541 for male and female, respectively) individual results obtained from the lifting performances of 528 athletes (male n = 270; female n = 258) participating in the Senior World Championship (between 2011 and 2023) in snatch and clean and jerk were analyzed. In the study, the frequencies and rates of the individuals included in the study according to different variables are presented with descriptive statistics. Various Chi-square analyzes were conducted to determine differences in distribution rates between groups. The significance level in the analyzes was determined as p < .05. It was determined that the successful lifts ratios of the athletes who achieved gold, bronze, silver medals in the light weight, middle weight and heavy weight categories of the male and female groups were higher than the unsuccessful lifts ratios in both lifting techniques (excluding silver medals in clean and jerk in lightweight for men; except bronze medals in snatch in lightweight for women). It was observed that the percentage rates in the unsuccessful lifts of athletes who achieved gold medals in both snatch and clean and jerk of the male and female groups were lower than the percentage rates in the unsuccessful lifts of athletes who took part in silver and bronze medals. It was observed that there was no significant difference between the distribution rates of successful and unsuccessful lifts distribution rates according to gender in both snatch and clean and jerk of both genders. It was observed that the successful lifts rates in both the snatch and clean and jerk of the male and female groups decreased from the 1st attempt to the 3rd attempt, and the lifting rates in the unsuccessful lifts increased. It has been observed that the lift attempts that determine the medal rankings of the groups in snatch, clean and jerk and total are the 2nd attempt and 3rd attempt. The findings can provide a comprehensive perspective on the in-competition factors that contribute to World Championship success in order to directly inform coach and athlete strategies. These findings may also be valid for national or regional champions and may include other strength-based sports with a similar structure.

Comprehensive property combination for biomedical application achieved in a Ti35Zr35Nb15Mo5Fe5Cr5 complex concentrated alloy

A novel Ti35Zr35Nb15Mo5Fe5Cr5 complex concentrated alloy (CCA) with potential for biomedical application was developed by vacuum arc melting and its microstructural evolution, mechanical properties, corrosion and wear behavior, and cytocompatibility were systematically evaluated. The alloy has an experimentally measured density of 6.37 g/cm³, suitable to fulfill the requirement of light weight. XRD analysis revealed that the as-cast and annealed specimens contain two BCC solid solution phases and a TiCr2 type Laves phase. The average microhardness (H) and elastic modulus (E) of the as-cast CCA are 618.39 ± 9.26 HV and 97.32 ± 3.58 GPa, respectively. Moreover, the yield strength (YS) of the as-cast alloy, estimated from elastoplastic analysis of the microindentation data, is 1203.94 ± 30.28 MPa. However, the CCA annealed at 1100˚C exhibits a microhardness of 833.08 ± 7.58 HV and a YS of 1669.65 ± 24.79 MPa, with the elastoplastic stress-strain response revealing no significant loss of plasticity due to the increased hard Laves phase. Corrosion and wear tests conducted in simulated body fluid confirmed the alloy's excellent corrosion and wear resistance. Cell culture experiments with MG-63 and HEK-293 cells demonstrated superior cell viability and proliferation compared to CP-Ti and 316 L SS. Moreover, confocal fluorescence images of MG-63 cells stained with AO/EtBr, Rh-123, and DCFH-DA revealed that the present CCA exhibits good biocompatibility. Thus, a comprehensive combination of low density, compatible elastic modulus, good strength with adequate plasticity, and sufficient corrosion resistance and biocompatibility were successfully achieved, unraveling significant potential of the alloy for biomedical applications.

Light-weighted quasi-zero stiffness device based on connected inclined beams on a flexible support

QZS isolators are particularly useful for low frequency excitations that are difficult to isolate for traditional isolation techniques. These isolators can be designed based on bistable structure which is very simple and of low weight. However, an external rigid restraint in transverse direction is often required for this kind of isolator which severely limits its application. This paper investigates a light-weighted QZS device that shows the QZS regardless of flexibility of the support. The device is based on inclined beams connected axially in series. Mechanism of the structure to generate the quasi-zero stiffness is discussed. A numerical model is developed for predicting its behavior. A series of tests were conducted to validate behavior of the structure and the numerical model, and a thorough numerical parametric study was performed. Based on the results, QZS isolators were designed and tested which is shown to have light weight and a good loading capacity.

Design and experimental evaluation of a compact inchworm piezoelectric actuator with bridge-type displacement amplification mechanism

Abstract Miniaturization is an important direction in piezoelectric actuator research, with related efforts focusing on reducing structural complexity and simplifying guiding mechanisms. However, some actuators experience backward movement after miniaturization design. There remains significant room for improvement in mechanism configuration and the design of flexible amplification mechanisms to further reduce actuator size. In this paper, a compact inchworm actuator with bridge-type displacement amplification mechanism (BTDAM) is proposed, which does not require an additional guiding mechanism and adopts a three-dimensional packaging approach with high space utilization and a compact amplification mechanism. Because the output capacity of the BTDAM significantly impacts the operating performance of the actuator, mathematical modeling and simulation analysis are conducted. Compared with the experimental results of the amplification ratio of the BTDAM, the error of the theoretical model was 5.05%, and that of the FEM analysis was 9.1%. The dimensions of the prototype are 23 × 23 × 19 mm, and it weighs 23 g. The test results indicate that the proposed actuator can achieve stable stepping motion without backward movement. Under a voltage of 75 V, the proposed actuator achieves a maximum motion speed of 384 μm/s and a maximum output force of 1.7 N. With its compact structure and light weight, the proposed actuator shows promising application prospects in the aerospace and bioengineering fields.

Transforming Tree Bark Waste into a Green Composite: Mechanical Properties and Biodegradability

In this study, a “green composite” material made from 60% tree bark and 40% polylactic acid (PLA) was fabricated and evaluated according to its mechanical properties and biodegradability. Biodegradation tests were performed in compost, simulated aquatic environments, and natural soil. In compost, the composite degraded steadily and reached 47% biodegradation after 11 weeks. In soil, the material quickly lost much of its tensile strength, and after 6 weeks, there were signs that the surface and the internal structure had started to deform. Biodegradation in aquatic environments also caused a loss of tensile strength after only a few weeks. Because of the high filler content, excellent biodegradability, and light weight, the composite material has a low environmental footprint. The material could be used in agricultural equipment such as plant pots.