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Objective To analyze the mechanical properties of the patellar (PT) and semitendinosus (ST) tendons from fresh-frozen human cadavers from a tissue bank using supersonic shear-wave imaging (SSI) elastography and tensile tests. Methods We tested seven PT and five ST samples on a traction machine and performed their simultaneous assessment through SSI. The measurements enabled the comparison of the mechanical behavior of the tendons using the stress x strain curve and shear modulus (µ) at rest. In addition, we analyzed the stress x µ relationship under tension and tested the relationship between these parameters. The statistical analysis of the results used unpaired t -tests with Welch correction, the Pearson correlation, and linear regression for the Young modulus (E) estimation. Results The µ values for the PT and ST at rest were of 58.86 ± 5.226 kPa and 124.3 ± 7.231 kPa respectively, and this difference was statistically significant. The correlation coefficient between stress and µ for the PT and ST was very strong. The calculated E for the PT and ST was of 19.97 kPa and 124.8 kPa respectively, with a statistically significant difference. Conclusion The ST was stiffer than the PT in the traction tests and SSI evaluations. The µ value was directly related to the stress imposed on the tendon. Clinical relevance The present is an evaluation of the mechanical properties of the tendons most used as grafts in knee ligament reconstruction surgeries.

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Young's modulus of elasticity (or stiffness, E) is an important material property for many applications of polymers and polymer-matrix composites. The common methods of measuring E are by measuring the velocity of ultrasonic pulses through the material or by resistance to flexure, but it is difficult for ultrasound to penetrate polymers that contain filler particles, and flexural measurements require large specimens that may not mimic the clinical case. Thus, it may be difficult to determine E using conventional techniques. It would be useful to have a relatively rapid technique that could be applied to small specimens, highly filled materials, and even specimens cured in situ. We suggest using a microhardness indentation technique that was originally developed for ceramic materials. We tested two unfilled rigid polymers, four resin composites, and four unfilled polymers with lesser hardness for this study. The study found that greater Vickers hardness loads yielded more consistent results than lesser loads. We developed a modified equation for E based on Knoop microhardness indentations. We concluded that laboratories may use a microhardness indenter to estimate the elastic moduli of polymers and resin composites. The results support our initial hypotheses that the slope of the equation relating the indentation parameter and the hardness/elastic modulus ratio was different for polymers and resin composites than for ceramics; however, the intercept is the same irrespective of the material tested.

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Anode-free Lithium metal batteries, with their high energy density (>500 Wh/kg), are emerging as a promising solution for high-energy-density rechargeable batteries. However, the Coulombic Efficiency and capacity often decline due to interface side reactions. To address this, a lithiophilic layer is introduced, promoting stable and uniform Li deposition. Despite its effectiveness, this layer often undergoes electrochemical deactivation over time. This work investigates lithiophilic silver (Ag), prepared via magnetron sputtering on a copper (Cu) current collector. Finite element simulations identify stress changes from alloying reactions as a key cause of Ag particle pulverization and deactivation. A high Young's modulus coating layer is proposed to mitigate this. The Ag2TiO3@Ag@TiO2@Cu composite electrode, designed with multi-layer structures, demonstrates a slower deactivation process through galvanostatic electrochemical cycling. Characterization methods such as SEM, AFM, and TEM confirm the suppression of Ag particle pulverization, while uncoated Ag fractures and deactivates. This work uncovers a potential failure mechanism of lithiophilic metallic nanoparticles and proposes a strategy for deactivation suppression using an artificial coating layer.

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The elastic properties of the folds govern the characteristics of vocal fold vibrations. This study addresses existing gaps by investigating the Young's modulus along the anterior-posterior direction in excised canine and cadaveric human vocal folds. Micro-indentation testing was conducted on six excised canines and three cadaveric human larynges. Multiple points along the medial glottal wall were indented to determine force-displacement, stress-strain relationships, and Young's modulus as a function of Green's strain. A vertical stiffness gradient was consistently observed in both canine and human samples, with higher stiffness in the inferior aspect compared with the superior aspect. The stiffness increased toward both the anterior and posterior directions from the mid-coronal plane, with a more pronounced increase at the posterior edge. Human vocal folds generally exhibited lower stiffness at low strains but were comparable to canine vocal folds at higher strains. These findings suggest that the canine larynx model is a reasonable representation of the human laryngeal tissues' elastic property trends. This analysis of the vertical stiffness gradient in canine and human vocal folds provides valuable data for improving experimental and numerical models of phonation.

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Conventional bitumen is a viscoelastic material composed of asphaltene and maltene. It is prepared by air-blowing, but this approach makes the bitumen more brittle and susceptible to temperatures. To decrease the temperature susceptibility, synthetic polymers or additives are used to make polymer-modified bitumens. Polymer-modified bitumens have poor storage stability and phase separation and are costly. Chitosan has free amino and hydroxyl groups. Some studies showed that chitosan can be used as a bitumen emulsifier, increasing emulsion viscosity. This study describes the synthesis of O-carboxymethyl chitosan (OCMC) from chitosan, and the same was blended in base bitumen VG10 and VG30 to improve its constitutive properties. VG10 and VG30 grade bitumen were characterized for penetration, softening point, kinematic and absolute viscosity, and ductility. OCMC-modified bitumens were also characterized by their rheological and mechanical properties. OCMC was used in the concentration range of 0.5 to 4.5 wt%. The study revealed that using sulfur increases the ductility and penetration of modified bitumen with 1.5 wt% of OCMC and meets the specification of VG40-modified bitumen as per BIS specification IS:73:2013. The study showed that blending 1.5 wt% of OCMC in VG30 base bitumen enhances the complex modulus to 76,517 Pa (at 42 °C) with a minimum phase angle of 68.58° and meets the VG40 bitumen specification. Simultaneously, blending 1.5 wt% of OCMC in VG10 base bitumen enhances the complex modulus to 64,454 Pa with a minimum phase angle of 77.39° (at 42 °C) and meets the VG30 bitumen specification. Studies showed that using SBS in a small amount of 0.25 wt% along with modified chitosan improves the rutting resistance and shear modulus by more than 67 °C at 1.1 kPa.

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Developing high-safety separators is a promising strategy to prevent thermal runaway in lithium-ion batteries (LIBs), which stems from the low melting temperatures and inadequate modulus of commercial polyolefin separators. However, achieving high modulus and thermal stability, along with uniform nanopores in these separators, poses significant challenges. Herein, the study presents ultrathin nanoporous aramid nanofiber (ANF) separators with high modulus and excellent thermal stability, enhancing the safety of LIBs. These separators are produced using a microfluidic-based continuous printing strategy, where the flow thickness can be meticulously controlled at the micrometer scale. This method allows for the continuous fabrication of nanoporous ANF separators with thicknesses ranging from 1.6 ± 0.1 µm to 2.7 ± 0.1 µm. Thanks to the double-side solvent diffusion, the separators exhibit controllably uniform pore sizes with a narrow distribution, spanning from 40 ± 5 nm to 105 ± 9 nm, and a high modulus of 3.3 ± 0.5 GPa. These nanoporous ANF separators effectively inhibit lithium dendrite formation, resulting in a high-capacity retention rate for the LIBs (80% after 240 cycles). Most notably, their robust structural and mechanical stability at elevated temperatures significantly enhances LIB safety under transient thermal abuse conditions, thus addressing critical safety concerns associated with LIBs.

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The objective of this study is to recognize and characterize the nanoscale phase modulus mapping of the asphalt film in pavement mixture cores using atomic force microscopy quantitative nanomechanical technology. The pavement core samples from the upper and middle layers of four highways and laboratory samples were taken as the research object. The phase modulus-macro property correlation of recovered asphalt was analyzed using mathematical statistics. The results showed that the pavement core samples had more significant multi-phase and diversified phase characteristics compared to lab samples. This indicated that the asphalt in the pavement core had an obvious phase separation phenomenon due to aging. The phase modulus of each sample was distributed across a relatively wide numerical range, and there were also many numerical points with large fluctuations. Especially for the mixture sample containing SBS (Styrene-Butadiene-Styrene)-modified asphalt, the phase modulus distribution mappings presented a multi-peak phenomenon. Hence, considering the distribution characteristics of the data, the box plot method was introduced. Compared with quantified results from laboratory samples, the phase modulus of SBS-modified asphalt increased by 0.96 times, 1.18 times and 1.15 times, and that of base asphalt increased by 0.59 times, 0.56 times, 0.42 times, 1.24 times and 0.39 times, respectively. This indicates that the aging degree of asphalt in the upper layer was generally greater than that of the asphalt in the middle layer and that there was an aging gradient in the direction of pavement depth. All points were within the 95% confidence band in terms of correlation fitting, indicating a better fitting effect between phase modulus and complex shear modulus, as well as between phase modulus and penetration. This research provides innovative ideas for future multi-scale numerical simulation and cross-scale performance model development of asphalt binders.

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The main concern with concrete at high temperatures is loss of strength and explosive spalling, which are more pronounced in high-strength concretes, such as Ultra-High Performance Concrete (UHPC). The use of polymeric fibers in the mixture helps control chipping, increasing porosity and reducing internal water vapor pressure, but their addition can impact its mechanical properties and workability. This study evaluated the physical and mechanical properties of UHPC with metallic and PVA fibers under high temperatures using a 23 central composite factorial design. The consistency of fresh UHPC and the compressive strength and elasticity modulus of hardened UHPC were measured. Above 300 °C, both compressive strength and elasticity modulus decreased drastically. Although the addition of PVA fibers reduced fluidity, it decreased the loss of compressive strength after exposure to high temperatures. The response surface indicates that the ideal mixture-1.65% steel fiber and 0.50% PVA fiber-achieved the highest compressive strength, both at room temperature and at high temperatures. However, PVA fibers did not protect UHPC against explosive spalling at the levels used in this research.

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The yield strength and Young's modulus of lattice structures are essential mechanical parameters that influence the utilization of materials in the aerospace and medical fields. Currently, accurately determining the Young's modulus and yield strength of lattice structures often requires conduction of a large number of experiments for prediction and validation purposes. To save time and effort to accurately predict the material yield strength and Young's modulus, based on the existing experimental data, finite element analysis is employed to expand the dataset. An artificial neural network algorithm is then used to establish a relationship model between the topology of the lattice structure and Young's modulus (the yield strength), which is analyzed and verified. The Gibson-Ashby model analysis indicates that different lattice structures can be classified into two main deformation forms. To obtain an artificial neural network model that can accurately predict different lattice structures and be deployed in the prediction of BCC-FCC lattice structures, the artificial network model is further optimized and validated. Concurrently, the topology of disparate lattice structures gives rise to a certain discrete form of their dominant deformation, which consequently affects the neural network prediction. In conclusion, the prediction of Young's modulus and yield strength of lattice structures using artificial neural networks is a feasible approach that can contribute to the development of lattice structures in the aerospace and medical fields.

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The current development of dental materials aims to improve their properties and expand their clinical application. New flowable bulk-fill composites have been released which, unlike what was previously common in this material category, are intended to be used alone and without a top layer, in various cavities. The study compares their kinetic of light transmission during monomer-to-polymer conversion on a laboratory-grade spectrometer, as well as their elastoplastic and aging behavior under simulated clinical conditions. Major differences in the kinetic of light transmission was observed, which is related to the degree of mismatch between the refractive indices of filler and polymer matrix during polymerization and/or the type of initiator used. Compared to the literature data, the kinetic of light transmission do not always correlate with the kinetic of functional group conversion, and therefore should not be used to assess polymerization quality or to determine an appropriate exposure time. Furthermore, the initial mechanical properties are directly related to the volumetric amount of filler, but degradation during aging must be considered as a multifactorial event.

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Board furniture's performance and scientific design are making it popular. Research on simplifying furniture joints reduces design cycles and costs and improves structural safety. In this article, using a cantilever beam to calculate deflection theoretically simplifies the L-shaped component model and yields a joint elastic modulus formula. Finite element analysis (FEA) confirms the effectiveness of this simplified model by comparing its results with experimental data. In simplified components, the joint elastic modulus increases with length (l2) and stabilizes at l2/b ≥ 6 (b is the board's thickness). The variation pattern of the joint elastic modulus equals that of the stiffness, proving its usefulness in assessing component deformation resistance. Furthermore, the component strength and stiffness are also affected by the screw spacing and connector type. In particular, the connectors type affects bamboo-oriented strand board (BOSB) component performance more than wood-oriented strand board (WOSB). Compared to WOSB, BOSB components have superior strength and stiffness and are more stable. The recommended screw spacing for L-shaped components is 48 mm. BOSB components fixed with two-in-one and metal nuts utilizing threads embedded in the board have better strength and stiffness, while for WOSB components, nylon nuts, and wooden dowel pins are more appropriate for securing.

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Recently, interest in tooth-colored fluoride-releasing dental materials has increased. Although physical and mechanical properties such as surface hardness, elastic modulus and surface roughness of the restorative materials have been investigated, the effect of different immersion media on these properties is still controversial. The aim of this study was to evaluate the nanohardness, elastic modulus and surface roughness of the fluoride release of tooth-colored restorative materials after immersion in acidic beverages. Prepared samples of three restorative materials (a highly viscous glass ionomer (EQUIA Forte; GC, Tokyo, Japan), a compomer (Dyract XP; Dentsply, Weybridge, UK), and a bioactive restorative material (Activa BioACTIVE; Pulpdent, MA, USA)) were randomly divided and immersed in distilled water, a cola and an orange juice for one week. The HYSITRON T1 950 TriboIndenter device (Hysitron, USA) with the Berkovich diamond indenter tip was used for all measurements. The nanohardness and elastic modulus of the samples were measured by applying a force of 6000 µN to five different points on the sample surface. Surface roughness measurements were evaluated on random samples by scanning five random 40 × 40 µm areas. The properties were measured at the initial and one week after immersion. The values of nanohardness, elastic modulus and surface roughness were tested for significant differences using a two-way analysis of variance (ANOVA) with repeated measures (p < 0.05). Tukey's honest significant difference (HSD) test was used for multiple comparisons. AB (Activa BioACTIVE) had the highest initial mean values for nanohardness. After post-immersion, the highest mean value for elastic modulus was the initial AB value. The lowest mean value for roughness of 100.36 nm was obtained for the initial DX (Dyract XP) measurement. Acidic beverages had a negative effect on the nanohardness, elastic modulus and surface roughness of the restorative materials.

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The effect of interstitial hydrogen on the elastic properties of bcc Fe, bcc Fe-Cr, and bcc Fe-Ni was investigated using density functional theory calculations. Our results indicate that the elastic moduli decrease linearly with increasing hydrogen concentration. The consequences of hydrogen for the mechanical properties of bcc Fe, bcc Fe-Cr, and bcc Fe-Ni were analyzed, considering various factors such as the ideal shear stress, Peierls stress, number of dislocation pile-ups, and critical crack growth lengths. At the same hydrogen concentration, compared to the bcc Fe and bcc Fe-Ni systems, fewer dislocation pile-ups and shorter critical crack growth lengths can facilitate the nucleation and propagation of cracks in the bcc Fe-Cr system. Finally, we propose a mechanism to explain the influence of Cr and Ni on hydrogen embrittlement.

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High pulse discharge breakage has a vast prospect as a fresh crushing mechanism for it has the capability to enhance the comminuting effect, however, the breaking mechanism is not yet well studied. In this orthogonal designed research, 27 indoor tests of high voltage pulse discharge (HVPD) for breaking concrete together with the determination of dynamic elastic modulus of concrete based on three variables, i.e. applied voltage, pulse number, and discharge electrode gap, were carried out at three levels. The effects of these factors were studied by using significance and range analysis. The results showed that among these factors, the pulse number has the greatest impact on the dynamic elastic modulus loss (DEML) of concrete, while the applied voltage has the least influence. By changing the value of pulse number and applied voltage, the DEML can be increased to 12.9% and 26.7%, respectively. The impact of the factors' combination was experimentally proven, and the resulting DEML of concrete broken by HVPD was obtained as 219.73 ± 9.58 MPa, which was 25.19% higher than the maximum of the DEML of concrete broken by HVPD in the orthogonal experiment under various individual factors. These findings provide technical references for improving the crushing efficiency of concrete materials and the engineering application of HVPD crushing technology.

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BACKGROUND: Real-time shear wave elastography (SWE) is a non-invasive imaging technique used to measure tissue stiffness by generating and tracking shear waves in real time. This advanced ultrasound-based method provides quantitative information regarding tissue elasticity, offering valuable insights into the mechanical properties of biological tissues. However, the application of real-time SWE in the musculoskeletal system and sports medicine has not been extensively studied. AIM: To explore the practical value of real-time SWE for assessing Achilles tendon hardness in older adults. METHODS: A total of 60 participants were enrolled in the present study, and differences in the elastic moduli of the bilateral Achilles tendons were compared among the following categories: (1) Age: 55-60, 60-65, and 65-70-years-old; (2) Sex: Male and female; (3) Laterality: Left and right sides; (4) Tendon state: Relaxed and tense state; and (5) Tendon segment: Proximal, middle, and distal. RESULTS: There were no significant differences in the elastic moduli of the bilateral Achilles tendons when comparing by age or sex (P > 0.05). There were, however, significant differences when comparing by tendon side, state, or segment (P < 0.05). CONCLUSION: Real-time SWE plays a significant role compared to other examination methods in the evaluation of Achilles tendon hardness in older adults.

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Purpose: This study investigated the fracture resistance and failure modes of custom-fabricated post- and core dental restorations using various CAD/CAM materials. Materials and Methods: Seventy-five mandibular second premolars were allocated to five groups (n = 15) and prepared for standardized post and core restorations. The groups included a control group comprising cast metal and four CAD/CAM materials: Vita Enamic, Shofu HC, Trilor, and PEKK. Fracture resistance was assessed using a compressive force at a crosshead speed of 1 mm/min until failure occurred. Data were analyzed using one-way analysis of variance (ANOVA) and chi-square tests. Results: The metal group had the highest fracture resistance (244.41 ± 75.20 N), with a significant variance compared to that in the CAD/CAM groups (p < 0.001). No significant differences were observed among the non-metallic groups. Conclusions: While several CAD/CAM materials displayed satisfactory flexural properties, cast metal posts showed superior fracture resistance in endodontically treated teeth but were mostly associated with catastrophic failure. The clinical application of CAD/CAM materials for post-core restorations presents a viable alternative to traditional metal posts, potentially reducing the risk of unfavorable fractures.

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The purpose of this study is to investigate whether the iontophoresis-assisted riboflavin delivery to posterior sclera with less delivery time, can achieve the same riboflavin permeation efficiency as the passive soaking way, and its effect on the mechanical properties of posterior sclera for accelerated scleral collagen cross-linking (A-SXL). In this study, 0.1% riboflavin solution was applied into the posterior sclera of porcine eyes either by the iontophoresis-assisted or passive soaking method, with delivery time of 5, 7.5, 10, 12.5, 15, 17.5, and 20 minutes, respectively.The fluorescence intensity and the distribution of riboflavin concentration in the 10 µm frozen sections of the sclera were evaluated by fluorescence inverted microscope. The posterior sclera with riboflavin treatment through either the iontophoresis-assisted or the passive soaking method for different durations ranging from 5 to 20 minutes was treated with ultraviolet A (UVA) irradiation at an intensity of 10 mW/cm2 for 9 minutes. The elastic modulus was determined at the physiological strain level using the uniaxial tensile test after ASXL. The results showed that the fluorescence intensity of riboflavin increased by prolonging the delivery time in both the iontophoresis and passive soaking groups, and the permeation depth of riboflavin remained constant over 15 minutes. The fluorescence intensity in the iontophoresis group was significantly higher than in the passive soaking group at 12.5 minutes and 15 minutes, respectively. The elastic modulus at 12.5 minutes in the iontophoresis group was significantly higher than in the passive soaking group at the same delivery time and showed no significant difference compared to the passive soaking group at 20 minutes. In conclusion, it indicated that iontophoresis-assisted delivery could not only shorten the surgery time but also achieve similar mechanical performance to the passive soaking method in ASXL.

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OBJECTIVES: The aim of this study was to determine the viscoelastic performance and energy dissipation of conditioned dentin infiltrated with polymeric nanoparticles (NPs) doped with tideglusib (TDg) (TDg-NPs). METHODS: Dentin conditioned surfaces were infiltrated with NPs and TDg-NPs. Bonded interfaces were created, stored for 24 h and submitted to mechanical and thermal challenging. Resin-dentin interfaces were evaluated through nano-DMA/complex-loss-storage moduli-tan delta assessment and atomic force microscopy (AFM) analysis. RESULTS: Dentin infiltrated with NPs and load cycled attained the highest complex modulus at hybrid layer and bottom of hybrid layer. Intertubular dentin treated with undoped NPs showed higher complex modulus than peritubular dentin, after load cycling, provoking energy concentration and breakdown at the interface. After infiltrating with TDg-NPs, complex modulus was similar between peri-intertubular dentin and energy dissipated homogeneously. Tan delta at intertubular dentin was higher than at peritubular dentin, after using TDg-NPs and load cycling. This generated the widest bandwidth of the collagen fibrils and bridge-like mineral structures that, as sight of energy dissipation, fastened active dentin remodeling. TDg-NPs inducted scarce mineralization after thermo-cycling, but these bridging processes limited breakdown zones at the interface. SIGNIFICANCE: TDg-based NPs are then proposed for effective dentin remineralization and tubular seal, from a viscoelastic approach.

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The mechanical properties of the sclera play a critical role in supporting the ocular structure and maintaining its shape. However, non-invasive measurements to quantify scleral biomechanics remain challenging. Recently introduced multi-directional optical coherence elastography (OCE) combined with an air-coupled ultrasound transducer for excitation of elastic surface waves was used to estimate phase speed and shear modulus in ex vivo rabbit globes (n = 7). The scleral phase speed (12.1 ± 3.2 m/s) was directional-dependent and higher than for corneal tissue (5.9 ± 1.4 m/s). In the tested locations, the sclera proved to be more anisotropic than the cornea by a factor of 11 in the maximum of modified planar anisotropy coefficient. The scleral shear moduli, estimated using a modified Rayleigh-Lamb wave model, showed significantly higher values in the circumferential direction (65.4 ± 31.9 kPa) than in meridional (22.5 ± 7.2 kPa); and in the anterior zone (27.3 ± 9.3 kPa) than in the posterior zone (17.8 ± 7.4 kPa). The multi-directional scanning approach allowed both quantification and radial mapping of estimated parameters within a single measurement. The results indicate that multi-directional OCE provides a valuable non-invasive assessment of scleral tissue properties that may be useful in the development of improved ocular models, the evaluation of potential myopia treatment strategies, and disease characterization and monitoring.

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This paper proposes a new impulse excitation technique using a square plate. First, the functional relationship between the modal frequency of the specimen and the geometrical dimensions and mechanical parameters was established by using the finite element method. Then, the continuous functional relationship derived by a homotopy method allowed the frequency ratios to be related to the thickness-to-length ratio and Poisson's ratio. By measuring the frequency ratios and thickness-to-length ratio, Poisson's ratio could be calculated using this functional relationship. When the density and Poisson's ratio were known, Young's modulus could be identified inversely in conjunction with the finite element analysis. Finally, a comparison test between this method and the traditional impulse excitation technique was designed and implemented, and the results showed that this method has advantages in both testing efficiency and accuracy. The study provides a new idea for system identification, which has important application value and promotion significance.