Thermally Induced Vibration Analysis of Composite Laminate Based on Equivalent Displacement Method

The main objective of this work is to check the compatibility of Finite element method (FEM) to determine the modal parameters of the rotor system and to compare the results with analytical method. Current work is an attempt to implement different finite element (FE) models for the estimation of modal parameters. Two different order elements from Beam, Axisymmetric and Solid FE models are considered. The analysis is carried out on the rotor system and the accuracy of the results and the computation time of the FE models are estimated. The FE results are compared with the analytical method. It is observed that FE model can be used to simulate even at higher order frequencies, which is a limitation of analytical model. The analysis shows that the FE results closely match with analytical method and also the study summarizes that proper choosing of FE helps in developing rotor models in both a desirable accuracy and efficiency. Finally, a Campbell diagram is generated using the analytical method and FEM. The critical speeds are also calculated from the Campbell diagram. The closeness of the results between the two methods is checked.

Review: Constrained finite strip method developments and applications in cold-formed steel design

Skull stiffness of children is of great significance to protect brain tissues during traffic accidents. In this paper, the effects of skull stiffness on traumatic brain injury (TBI) are investigated by using a validated 6-year-old child head finite element (FE) model according to Chinese standard GB/T 24550-2009 Results showed that the HIC value, intracranial pressure, Von Mises stress and shear strain of brain tissue increased with the decrease of skull stiffness during the impact of FE model with engine hood. Therefore, the injury risk of the child head decreases with the increase of skull stiffness. And the skull with higher stiffness can provide a better protection for brain tissues during traffic accidents.

Core body temperature is an important indicator of medical treatment. Sudden changes in core body temperature can be a precursor to neurodegenerative diseases such as Parkinson's disease. These diseases have the potential to strike at any time, therefore, long-term monitoring of core body temperature and alerting to sudden changes in temperature become important. In this paper, we designed an in-ear thermometer to monitor the core body temperature with the help of smartphone.

Purpose – In former work, test results of cracks in aluminium panels under cyclic shear buckling showed that cracks in the tensile stress field of a buckle propagate. The main influencing factor for the crack growth rate is the maximum principle stress. A simplified approach for crack propagation analyses based on this finding showed limitations for application on larger cracks because it disregarded the increasing out-of-plane deformation for larger cracks as well as stress redistributions. The purpose of this paper is to improve the results of the simplified approach with the help of finite element method (FEM). Design/methodology/approach – An approach for crack propagation based on FEM is presented taking into account the mutual interaction of cracks and buckling. The finite element (FE) model, which is described in detail, respects the boundary conditions of the test-set-up. Different initial crack positions, loads and panel thicknesses are analyzed. Results of the stress intensity factors KI calculated by the ABAQUS® FE model provide a function which is used to run a crack propagation analysis based on Forman law. Findings – The results of the FE-based crack propagation solution are in good agreement with test results and improve the prediction of the simplified approach. It is not restricted in terms of panel thickness, crack position or applied shear load. Research limitations/implications – Limitations of the FE-based crack propagation solution compared to the experimental results are discussed. These are, the sensitivity of crack propagation analyses to initial crack length and deviations of the experimental settings from the ideal FE model. Originality/value – The interaction of cracks and buckling in aluminium shells is mainly disregarded both in research and industrial work, but can be of interest considering, accidental damages in fuselage side shells. Cracks propagate under shear load as it was shown in former work. The FE modeling of the tests presented in this paper proves the mutual interactions of crack propagation and buckling deformation.

Nonlinear vibration of the sandwich beam with auxetic honeycomb core under thermal shock

A method for continuous box-girder bridge structure finite element (FE) model updating based on static-load testing is proposed. The procedure includes field static-load testing, FE modeling, FE model (parameter) updating, etc. Based on this procedure, the structure FE model updating for an expressway 5-span pre-stressed concrete continuous box-girder bridge is conducted. And the bridge structure static FE model, which is consistent with the static-load testing actual measure response, is gained. The updated FE model (parameter) is foundation of structural performance evaluation for the bridge.

In this paper a finite element investigation of the tillage of compacted soil, using the modified Drucker-Prager plasticity material model, was described. The finite element method is adequately contributing to the development of understanding the reality of cutting soil. In most earth moving machinery, the working tool is always a blade. Hence for the tillage systems, accurately predicting the forces between blade and soil is of prime importance in helping to enhance productivity. Parallel computing of the models was fulfilled in HP BL680c G5 server with LS-DYNA 971 MPP software. Three different blade shapes were analyzed by the finite element model. Results show that reverse-rotational rotary tool can work for the cutting of compacted soil. Proper structural parameters of rotary blades can reduce the power consumption. It is perfectly feasible to apply the proposed composite rotary tiller to compacted soil deep-tilling with low power motor. The simulation results were also compared with classical soil mechanics theories for blades (the McKyes approach). A good correlation was obtained between the simulation results and McKyes approach.

Ultimate bearing capacity analysis of self-anchored suspension bridge with steel box girders considering local buckling

The primary objective of this numerical study is to provide a finite element (FE) analysis approach for segmental structures. The study was conducted using a hollow circular segmental structure model capable of adequately imitating real structural behavior and deals with the effect of varying number of segments on structural performance. In order to verify the FE procedure conducted by DIANA software, comparisons are made with the acquired numerical results and the results taken from previous experimental studies for 1 reinforced concrete (RC) beam, 2 post-tensioned (PT) beam, and 3 segmental post-tensioned beams (SPT). For the considered cases, 1D line, 2D shell, and 3D solid FE models are made, and it is found out that the 3D solid model with interface elements yields the most plausible results. Further, the FE model was constructed to accurately predict segment joint behavior concerning the relationship between the number of segments, concrete compressive strength, and the width of the openings at the segment joints up to collapse. In this study, a hollow circular segmental structure model is utilized to mimic real structural behavior, presenting a novel perspective on internal force transfer mechanisms within segmental structures. Moreover, the FE model is tailored to accurately predict segment joint behavior, elucidating the intricate relationship between the number of segments, concrete compressive strength, and the width of openings at segment joints up to collapse. In addition to presenting a robust numerical analysis framework, this study contributes novel insights into the complex interplay between segmental geometry, material properties, and structural behavior, thus advancing the state-of-the-art in segmental structural design. Thus, a modular construction methodology is proposed for segmental beam type structures ensuring safety, efficiency, and flexibility in challenging load conditions.

The object of research is cured thermosetting epoxy polymer and FRP on the base of the same polymer matrix. The purpose of this research is to develop the finite element (FE) method in the modeling of cured thermosetting polymers and FRPs to predict their mechanical and thermal properties. The structural mathematical modeling with subsequent computer FE modeling was performed. The results of FE modeling were compared with the experimental data of cured polymer's and FRP's tensile strength and deformations under mechanical load at different temperatures. The design of the polymer's FE model was based on the tetrahedral supramolecular structure and then transformed into FRP's model by integrating glass fiber rods. Using the structural density as the structure model's parameter, the relative size and disposition of the finite elements were determined. The viscoelastic properties are set in the model by regulating the structural density and compressive/tensile properties of joints. The long-term plastic deformation and stress relaxation were determined as the result of the supramolecular structure's inner shearing with the decrease of its structural density. The FE models of the cured epoxy polymer and FRP were developed, making it possible to predict short-term and long-term deformations under load with high accuracy considering the temperature factor.

Relación de las profesiones y las condiciones laborales con la neumonía adquirida en la comunidad

Objective To explore the establishment of 3D thoracic model by finite element methods, and study the mechanical mechanism of minimally invasive surgery for correcting the chest wall deformity, and provide personalized surgery solution in the future. Methods According to admission and exclusion criteria, we selected 10 cases of pectus carinatum that received chest CT scan. The finite element model of pectus carinatum was established and analyzed by Mimics, ABAQUS, etc. The validity of finite element method for chest wall was verified by comparing the sternal displacement between the simulated values and actual values with the same force. Results The 3D finite element model of pectus carinatum was successfully established and analyzed. The stress distribution of the 10 cases in the posterior ribs was mainly in the 1-6 ribs on both sides, mostly concentrated in the 4th to 6th ribs, and the stress was symmetrical on both sides. Statistical analysis showed that the displacement value of the sternum was correlated, and the validity of the model was verified. Conclusion Mimics, ABAQUS and other finite element modeling and analysis software can effectively establish the thoracic 3D finite element model and mechanical analysis, which can help the further development of personalized minimally invasive surgery for correcting chest wall deformities. Key words: Pectus carinatum; Chest wall deformity; Finite element analysis

Accurate assessment of the three-dimensional shrinkage stress evolution for photopolymerized dental filling materials: Mechano-chemo-thermo-coupled finite element modeling and experimental validation.

The various measurement procedures for determination of electromagnetic parameters for the induction motor (IM) equivalent circuits including the rotor deep-bar effect were proposed in the literature. One of them is the procedure based on the load curve test (LCT). Since the execution of the LCT can pose some difficulties, especially in industrial conditions, as an alternative, the finite element method (FEM) can be employed to simulate the IM operation under the LCT. In this work we developed the optimisation technique for the finite element (FE) model. This technique is performed with the use of the stator current space-vector components which determine the IM input active and reactive power consumption during no-load operation. Relying on the LCT simulation carried out with the optimised FE model the inductance frequency characteristic can be determined and then used as the reference characteristic in the electromagnetic parameter estimation for the IM equivalent circuit including the rotor deep-bar effect. The presented research results demonstrate proper conformity between the inductance frequency characteristics obtained from the LCT performed experimentally and determined by means of the optimised FE model. Satisfactory conformity is also achieved in the case of the torque-versus-slip frequency curves acquired from the measurement and calculated by the IM space-vector model with estimated electromagnetic parameters. All of this validates the effectiveness of the proposed technique for the FE-model optimisation and the usefulness of the presented approach using the FEM in the electromagnetic parameter estimation for the IM equivalent circuit including the rotor deep-bar effect.