Mechanical Analysis Method Research Articles

A simple method for mechanical analysis of pressurized functionally graded material thick-walled cylinder

The complex function method is employed to establish a mechanical model for pressurized thick-wall cylinders made of functionally graded materials (FGM). This model is applicable to all radial varying modes of material properties, including both continuous and discontinuous variations in Young’s modulus and Poisson’s ratio. The main concept behind this mechanical model involves dividing the thick-walled cylinder into concentric thin cylinders, each equipped with a pair of analytical functions representing stress functions. By imposing continuity conditions between adjacent thin cylinders and considering the stress boundary conditions of the entire structure, all unknown forms of analytical functions can be determined. Subsequently, by establishing the correspondence relationship between these analytical functions and stress or displacement, it becomes possible to solve for the stress or displacement at any radial position within the thick-walled cylinder. Through comparison and verification against the numerical simulation results, it can demonstrate that as long as the differential scale is sufficiently small, high accuracy can be achieved in the final result. In other words, solutions obtained for multi-layered hollow cylinder converge toward those obtained for continuously graded thick-walled cylinder. Notably, by starting from the level of stress function and avoiding complex differential and integral equations, a linear equation system can provide information on stress and displacement distributions along the radial direction. Therefore, compared to other solving methods available, this proposed approach offers simplicity and applicability.

Research and Experiment on Airflow Field Control Technology of Harvester Cleaning System Based on Load Distribution

The wind sieve cleaner is widely used in the screening system of combine harvesters due to its compact structure and efficient screening capability. In order to study more deeply the feeding load distribution of the combine harvester and the influence of the airflow field on the clearing effect, a mechanical analysis method was adopted to analyze the dynamics of the material in the inclined airflow, and a kinetic model was established. At the same time, the motion state of the material in the airflow field was explored, and combined with the actual orthogonal test, the response surface model of factors and indicators was established. Experimental validation was carried out. It provides an important research foundation and theoretical basis for optimizing the structural parameters of the screening system and improving its operational performance.

Topology optimization based on combined mechanical analysis and variable density method for casting structure

In this study, a topology optimization method based on combined mechanical analysis and variable density is presented for a large-scale casting structure with complex thin-walled structures. First, the mechanical analysis model of the frame is established, the first-order bending and torsional modes and stiffness values of the all-cast aluminum frame are obtained, and the basic mechanical parameters such as bending/torsional mode and stiffness constraints needed for topology optimization are defined. Using the variable density method, unneeded material that can be removed from the casting structure is identified. According to the design requirements, the optimization objective function and constraint conditions are established, and the variable density method is used to solve the problem. Analysis of the mechanical results before and after topology optimization reveals that the modes and stiffness values are larger than the target values, and the mass of the frame is reduced by 10.2 kg (i.e. 13.9%) compared with the original design. The application of the combined mechanical analysis and variable density method to a casting structure can effectively achieve lightweight design.

Modal analysis of honeycomb panel satellite structure based on MSC Apex

Modal analysis plays an important role in the process of Satellite structure development. In this paper, the honeycomb sandwich plate and the satellite structure are taken as the research objects, and the corresponding finite element models are established. The analysis results of the actual modeling of honeycomb plate and the equivalent modeling of sandwich sandwich plate are obtained, and the fundamental frequency deviation of the whole satellite structure is discussed when the equivalent correction coefficient γ of honeycomb plate is different. The results show that the maximum relative error of the modal frequency between the equivalent method of sandwich sandwich plate and the actual modeling is 2.8%. Therefore, the equivalent method can be applied to large-scale finite element analysis and calculation, and the calculation efficiency can be improved. When the value of γ is 0.4∼0.6, the vibration modes of the whole satellite structure are basically consistent, and the maximum fundamental frequency difference is 10%. The results can evaluate the accuracy of the sandwich sandwich plate equivalent method for satellite mechanical analysis.

Mechanical simulation and debonding risk analysis of OLED panels with optically clear adhesives

This paper presents a mechanical simulation model and analysis method for OLED panels. The functional layers within the panel are bonded using optically clear adhesives (OCAs), which are pressure-sensitive adhesives (PSAs), resulting in a soft interface bonding problem. It was discovered that the normal tensile debonding strength of OCAs was significantly lower than the shear debonding strength. To address this issue, a three-layer structure simulation model of “hard + soft + hard” is established, which allows for analyzing the screen folding problem of any radius. Additionally, a suitable element mesh generation strategy for multi-layer structure screens is proposed. A debonding risk index based on pressure is introduced by comparing the interlaminar normal and maximum principal stress. The influence of thickness, bending radius, and Young’s modulus on longitudinal stress and debonding risk index is examined. It is observed that the influence of thickness and Young’s modulus on debonding risk is non-monotonic, indicating the presence of an optimal solution. The high debonding risk area is located at the beginning of the folding mechanism and screen bonding. The proposed debonding risk index is not only applicable to OCAs but also to all PSA with similar structures.

Analytical approach to piezoelectric model synthesis with the use of Cauer's method for system design.

Piezoceramic materials have unique property which enables direct and bilateral conversion between mechanical and electrical energy. This ability facilitates significant miniaturisation of technology and opens many opportunities in design of new actuators and energy harvesters. Mathematical modelling of piezoelectric modules is notoriously hard due to complex constitutive equations defining mechanical and electrical energy conversion. The article presents research on a new synthesis method based on the Cauer's method. Mechanical damping is introduced with the use of Rayleigh's approximation. A discrete electromechanical model is formed based on the Mason's piezoelectric model. The proposed approach allows modelling of piezoelectric systems based on a set of characteristic frequencies. The method allows a more general approach to the problem of modelling new systems, as opposed to application-oriented methods seen in literature. A non-standard model analysis method using edge graphs and structural numbers is also verified as a potential alternative for matrix-based method. The authors compare their precision and computation requirements. The structural method of mechanical model analysis gave identical results as the reference matrix method. However, the non-classical algorithm took much longer to calculate and was using more memory. The electromechanical model analysis has shown an error of 5% in comparison to resonance frequencies taken from a reference plate specification. The calculated magnitude of displacement was well above the capability of a 3.5mm thick piezoelectric plate. The synthesis method presented in this paper allows synthesizing piezoelectric cascade models based on limited information in form of characteristic frequencies. Currently this method allows a coarse approximation of the real piezoelectric parameters with limited number of inputs. The additional method of analysis based on structural numbers offers a promising alternative to matrix calculations but requires a more thorough investigation of the computational power required to determine whether it can compete with existing algorithms.

Quantitative analysis method for absorption mechanism and energy consumption of CO2 capture by amino acid ionic liquids

Amino acid ionic liquids (AAILs) are attractive candidates for CO2 capture due to their high solubility for CO2. Quantitatively analyzing the interaction of amino groups in AAILs with CO2 and evaluating the energy consumption of CO2 capture is critical to the molecular design of ideal AAILs. In this work, a thermodynamic model based on the cubic plus association equation of state was proposed to calculate the contribution from the chemical reactions between various stoichiometric ratios of CO2 and AAIL (Nm:n,m:n is stoichiometric ratio) on CO2 solubility. The results show that the larger contribution to the CO2 solubility in [Glu], [Tyr] and [Gln]-IL with strong polar groups is derived from association scheme N1:2, while the N1:1 association interaction is the dominant contribution of [Gly], [Ala], [Val] and [Pro]-IL with hydrogen atom or short alkyl side chains, and [VBIm]-IL with multiple amino groups. The N2:1 association interaction is primary between CO2 and [Cho][His] or [Cho][Arg]. Besides, the contributions of these association effects are greater than that of dispersion and repulsion to CO2 solubility. Then, the solvent cyclic capacity and regeneration energy of AAILs in the pressure swing and temperature swing CO2 capture system were estimated. More amino groups result in higher regeneration energy consumption and do not necessarily increase solvent cyclic capacity. Among the studied AAILs, [Cho][Gly] which exhibits high cyclic capacity and low energy consumption has great potential in CO2 capture solvent.

Error mechanism analysis and accuracy enhancement method for circular gratings angle-measuring system

In order to raise the accuracy of the circular gratings angle-measuring system, a comprehensive error model is established, and a novel compensation method is proposed. Firstly, many error sources, including the rotary errors of axis system, the installation eccentricity and the inclination of the circular grating disc, the graduation line error of the circular grating disc, and the installation error of the multiple readingheads of the high precision circular gratings angle-measuring system are comprehensively taken into consideration. Secondly, the position and attitude errors are propagated to the angular position outputs, thus the mathematical relationships between error sources and the angular position error are established. Aiming at multiple readingheads system, the mechanism of influence of the error sources on the angular position error is unveiled, and the mechanical error identification and reduction method is proposed. After that, a checking system with a 23-mirrored polygon and an autocollimator is set up, and the complete combinatorial method of separating the angular position errors from the readouts of the autocollimator precisely is used. Finally, the angular position error compositions are separated by the harmonic analysis method, and the concerned error coefficients are compensated. The experimental results show that the nominal indication interval value of the angular position errors is reduced to 0.23" by the mechanical error reduction method, and then the nominal indication interval value of the angular position errors is reduced to 0.12" by software measurement method. And the two sets’ repeatability of the separated biases of the 23-mirrored polygon before and after compensating is 95%.

Research and Analysis of Coulomb Friction in Landing Gear Shimmy

Aircraft are subject to small disturbances during taxiing, many of which are accidental and difficult to explain. Although nonlinear factors are considered in traditional analysis, Coulomb friction is generally ignored, and the interaction and common effects of nonlinear factors are mostly not discussed. In this paper, the dynamic model of shimmy is established, and the influence of Coulomb friction on shimmy is studied by using bifurcation theory and the structural mechanics analysis method. The results show that the system with Coulomb friction has subcritical Hopf bifurcation and that the system with square damping has supercritical Hopf bifurcation. Although the two do not change the stability of the system, their cooperation can improve the stability of the system. The Coulomb friction torque of the system has a complex piecewise functional relationship with the stability distance, rake angle, and acceleration. Some combinations will lead to very low Coulomb friction and deteriorate the anti-interference ability of the landing gear. This paper provides theoretical basis and support for the rational design of structural parameter collocation, enhancing the antidisturbance ability of the system during constant-speed or variable-speed taxis and explaining the shimmy phenomenon in the process of variable-speed taxis of some aircraft.

Approximation method for yielding support analysis in high ground stress soft surrounding rock tunnels.

In solving the whole process of interaction between soft rock and yielding support in high-stress environments in tunnels using mechanical analysis methods, it is challenging to simultaneously satisfy both displacement coordination and static equilibrium at the contact surface between the rock and the support structure. This paper, based on the mechanical analysis of rock and rigid support, considers the impact of the circumferential installation of yielding elements on radial displacement, and proposes displacement approximation and support force approximation methods using displacement coordination and static equilibrium as approximation conditions. The study fits curves of numerical simulation results and laboratory test results of yielding elements, and attempts to directly use the laboratory test data set of yielding elements as computational data. By calculating two circular tunnel examples and comparing the effects of the trisection method, bisection method, and substitution method on the convergence of the displacement approximation method, the effectiveness of the methods proposed in this paper is verified. The research results show that the two approximation algorithms proposed in this paper have good accuracy and reliability in calculating the relative displacement of rock and yielding support structure contact surfaces, and the support force of yielding support. The bisection method outperforms the trisection and substitution methods in terms of stability and convergence. However, there are certain limitations in this study, such as the effectiveness of the algorithm may be influenced by geological conditions; the complexity of actual geological conditions may exceed the assumptions of the current rock-support mechanical analysis model.

Evaluation and Comparison of Research Methods on Driving Factors of Carbon Emission in Industrial Parks

As the primary territories of regional carbon emission and energy consumption, most industrial parks only simply stack technology and policy under the urgent goal of emission reduction and carbon reduction. As a result, certain measures may even have negative impacts. As the primary means to determine the characteristics of carbon emissions in industrial parks, studying the driving factors of carbon emissions and proposing targeted measures can effectively achieve the carbon emission reduction goals. However the mechanism analysis of driving factors of carbon emission in industrial parks is the important means to study the characteristics of carbon emission. The selection of driving factors is many and complicated, and the selection of mechanism analysis methods is different, so it is difficult to have a comparison of research results Based on the quantitative relationship model between carbon emissions and driving factors and the method of action mechanism analysis in industrial parks, this paper evaluates and compares the relevant studies, summarizes their advantages and disadvantages, and makes relevant comments and prospects. For providing reference for the practice of driving factors of carbon emission in industrial parks, and put forward the basis for the research of carbon emission prediction.

Functional degradation reliability analysis for non-uniform wear of multi-rotating joints of mechanical structures

Failure of the aircraft landing gear lock mechanism can result in the inability of the aircraft to take off and land properly, and its failure can cause critical results. The aircraft lock mechanism is characterized by multiple joints. Based on the performance degradation phenomenon of the lock mechanism, a reliability analysis method of the lock mechanism with non-uniform wear of multiple joints is proposed, which takes into account the effect of non-uniform wear of multiple joints on the motion accuracy of the motion mechanism, and investigates the reliability analysis of the degradation of the angle of the lock hook and the calculation of the whole lifetime cycle. Firstly, the lock mechanism lock hook angle degradation eigenvolume model is established according to the functional principle of the lock mechanism. Secondly, the lock hook degradation angle is obtained by establishing the kinetic equations to calculate the non-uniform wear of each joint separately. Finally, the degradation path is fitted by the Wiener process to carry out the reliability analysis and the whole lifetime calculations. The results show that the proposed method is capable of providing maintenance strategies to meet the reliability requirements for the performance degradation of multi-joint kinematic mechanisms of mechanical systems.

Calculation and properties of thermal stress of monolayer film and solution of thermal stress of multilayer infrared antireflection coating by finite element analysis

The deposition of infrared antireflection coatings on silicon lenses is a widely practiced technique that has been extensively investigated by researchers over an extended period. Thermal stress is essential to the adhesion between the film and the substrate. To measure the magnitude of thermal stresses, we use the mechanical analysis method to convert thermal stresses into shearing and peeling stresses. Expressions for these two stresses are then derived. Then, we analyzed the effect of the monolayer film's properties on the silicon substrate's stress. The results indicate that peeling stress is the main factor affecting the adhesion between the film and the substrate, and various approaches can be employed to successfully mitigate the peeling stress exerted on the substrate. The influence of the multilayer film's structure on the peeling stress experienced by the silicon substrate was investigated through the utilization of finite element analysis. In this study, three distinct infrared antireflection coatings were deposited on silicon substrates individually. Subsequently, these coated substrates underwent rigorous environmental testing. The findings from this testing confirmed the accuracy of the stress analysis results obtained by finite element analysis for the multilayer film. Our research has resulted in solutions for determining the magnitude of shearing and peeling stress. We have employed finite element analysis to identify a suitable structure for an antireflection coating that exhibits minimal peeling stress. This advancement has the potential to improve the effectiveness of design processes and the adaptability of infrared antireflection coatings in various environmental conditions.

Characterization of viscoelastic properties of yarn materials: Dynamic mechanical analysis in the transversal direction

Abstract Warp knitting creates very challenging dynamics due to its high production speeds. On the one hand, this makes it method of choice for many products in various fields. On the other hand, not all materials are suitable for such high productivity. With the current generation of machines being limited to only achieve their maximum speed of around 4,400 min−1 with highly elastic yarns, it is desired to gain a deeper insight into yarn behavior in such highly dynamic environments. Among other influences, resonance effects gain high significance as they may result in high loads on the used materials; therefore, yarn breakages interrupt the production and decrease the quality of the product. To extend the material choice, especially high-performance fibers, for high productivity, a deep understanding of the intrinsic properties of the yarn is required. In particular, the viscoelastic properties are of importance. This study proposes a method to determine these characteristics using the dynamic mechanical analysis method. For the purpose of finding the damping in the transversal direction to the yarn axis, the variant of free oscillation is chosen. For the trials, a high-speed camera is suspended above a testing rig. On this rig, a yarn sample is clamped and then displaced from its rest position. The resulting oscillation is recorded and later extracted from the video. From the decrement of the maxima of the amplitude and corresponding time intervals, the damping factor is determined. It decreases with higher initial deflection. Summarised the developed trial setup proved suitable for the determination of the viscoelastic properties in transversal direction.

An Analytical Method for Mechanical Analysis of Offshore Pipelines during Lifting Operation.

The lifting operation of offshore pipelines is an important step in ocean pipeline engineering. An effective analytical method is developed for investigating the mechanical properties of the pipeline based on mechanical, physical, and geometric relationships. By using the shooting and the secant methods to transform the boundary value problem into an initial value one and then solving them with the Runge-Kutta method, the deformation and mechanical properties of the pipeline are calculated. Furthermore, based on the Det Norske Veritas (DNV) offshore standard, the mechanical properties of the pipeline are checked. The finite element method (FEM) by Orcaflex is employed to verify the accuracy of the analytical model. The effects of some factors such as the current velocity and lifting point position on the mechanical properties of the pipeline are analyzed based on the analytical model. The results indicate that the change in current velocity during the lifting process has a minimal effect on the pipeline, but the change in lifting point position significantly affects the deformation and mechanical properties of the pipeline.

Determination of the ignorable boundary condition and standard sample for a novel in-situ dynamic mechanical analysis method on soft matter

An in-situ Dynamic Mechanical Analysis (DMA) method for soft matter developed by our group [Wu. et.al. 2022] encounters the problem of irregular samples, which significantly vary in shape and size in practice, therefore a standard sample “large enough” to ignore the boundary and size effects is necessary to determine the baseline of test and build the correspondence between this new method to classical mechanical tests. In this work, we use finite element analysis to approach the optimal size of a brick sample where the stress on the boundaries in three spatial directions are ignorable, and certified the results by testing a series of silicone gel samples on the in-situ DMA device. The stress-strain of tensile and compression are characterized. The material properties of gel are chosen to be close to the biological soft tissue. The size of 40mm(L)×40mm(W)×20mm(H) is determined to be the optimal result.

Investigation of coupled aerodynamic characteristics in channel wing propeller configuration

This work studies the lift enhancement effect with a channel wing propeller configuration. Numerical simulations and flow field analysis are performed to investigate the influence (the relative position and spacing, angles of attack (AoA), propeller speed, incoming flow speed) on the lift enhancement effect. The aerodynamic performance is numerically simulated by the method of multi-reference frame (MRF). Numerical results demonstrate that the propeller suction process has a very significant lifting effect. The lifting effect can reach 5 times contrast to the single channel wing. The propeller located at 100% of the chord length of the channel wing achieves the best lift enhancement effect. The intervention of the propeller delays the flow separation at the trailing edge of the channel wing. It holds a high lift coefficient at a high AoA. The lift line slope remains essentially unchanged in the range of 0–30°. It is roughly the same as that of the single channel wing configuration before stall. With the increase of propeller speed or incoming flow speed, the lift coefficient increases significantly. The lift line slope is approximately the same at different speeds. The regularity functions of different coefficient are obtained through mechanism analysis and least squares data fitting methods. The lift coefficient changes with the AoA in a linear relationship and with the propeller speed or incoming flow speed in a quadratic relationship.

Fabrication process optimization of nHA–CNTs-reinforced PEEK hybrid nanocomposite

Compression molding is the leading fabrication process for polymer composites. The settings of process parameters highly influence the mechanical properties of composites. This study optimized the ball-mixing and compression-molding process parameters for the fabrication of hybrid nanocomposites based on polyetheretherketone (PEEK), multiwalled carbon nanotubes (MWCNTs) and nano-hydroxyapatite using the Taguchi method. The elastic modulus examined using the nanoindentation method of static mechanical analysis was taken as the output response variable. The optimum levels of mixing time, mold temperature, mold pressure and holding time process parameters for the maximum elastic modulus were found to be 90 min, 400°C, 150 bar and 15 min, respectively. The analysis of variance technique showed that the mold temperature had the highest contribution (46.82%) in enhancing the elastic modulus to the largest value. The elastic modulus and hardness of the PEEK-based hybrid nanocomposite with 30 wt.% nHA and 3 wt.% MWCNTs were observed to be 83 and 65% higher than those of pure PEEK, respectively. The hydrophilicity of PEEK was improved with the reinforcement of nHA, attributed to the presence of oxygen-containing functional groups in the chemical structure of nHA.

Structure, and Mechanical and Thermal Properties of Vinyl-Polydimethylsiloxane/Zinc Dimethacrylate/Isobutylene-Isoprene Rubber Composites

The vinyl-polydimethylsiloxane (v-PDMS) composite reinforced by micron size ZDMA particles previously showed high modulus, thermal stability, solvent-proofness, and good processing ability. However, its poor damping properties limited usages. Thus, incorporation of new polymers into the composite was imperative to improve its loss factors. With a similar solubility parameter and good damping properties, isobutylene-isoprene rubber (IIR) was melt-blended in, then heat-pressed and cross-linked. The v-PDMS/ZDMA/IIR composites gotten were characterized by scanning electric microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), mechanical tests, dynamic mechanical analysis (DMA) and thermal gravimetric analysis (TGA) methods. The IR spectra of the composites illustrated that the incorporation of IIR was successful. The SEM observation showed good dispersion of the IIR, and the increasing deformation on the surface with growing dosage of IIR. The incorporation of IIR rubber decreased the composite’s modulus sharply and also the tensile strength, but improved the elongation and damping properties of the v-PDMS/ZDMA composites at low temperature. The TGA test results in N2 gas showed the composites had good thermal stability below 350 °C, then deteriorated at higher temperature owing to the decomposition of the IIR at 400 °C. The decomposition activation energy at 400 °C was determined by the Kissinger method.

Functional properties of nano-SiO2/pinewood-derived cellulose acetate composite film for packaging application

Petroleum-based plastics are widely used because of their practicable properties and low cost. However, people are equally concerned about the environmental damage generated by non-biodegradable petrochemical plastics. In this study, pinewood was employed as the raw material to prepare cellulose acetate and further synthesize the degradable composite films, which showed potential feasibilities to substitute the traditional petroleum-based plastics. In order to improve the barrier performance, hydrophobic performance, and mechanical properties of the film materials, nano-SiO2 was introduced as functional filler for experimental exploration. The tensile strength, light transmittance, water vapor transmittance, microstructure, and crystalline structure of the nano-SiO2/pinewood-derived cellulose acetate composite films were determined by mechanical analysis, optical analysis, SEM, XRD, FT-IR, and barrier characterization methods, respectively. The results exhibited that the prepared films with the inclusion of nano-SiO2 did not conduct reduction in transparency due to its good dispersion in the composite film. The barrier property, hydrophobic performance, and mechanical properties of cellulose acetate composite film were effectively improved due to the interaction between nano-SiO2 and cellulose acetate molecular chains by the hydrogen bonds formed between hydroxyl groups. It was confirmed that the nano-SiO2/pinewood-derived cellulose acetate composite films exhibit great application potential as an environmentally friendly and efficient material for packaging.