CAE Analysis of Dynamic Stiffness and NTF of Exhaust Attachment Point for NVH Improvement

Abstract Background and Study Aim Cervical spondylotic myelopathy (CSM) is a common degenerative disease that mainly occurs in elder patients, leading to different degrees of neurological dysfunction. Spinal cord involvement is mainly distributed at the C3–C7 segments, but it may also involve up to the C2 level. This study aimed to assess the clinical efficacy and safety of open-door laminoplasty using a new extensor attachment-point reconstruction technique for treating CSM involving the C2 segment. Patients and Methods Fifty-nine patients with CSM involving the C2 segment and undergoing open-door laminoplasty were included in this retrospective study. Based on the titanium plate used in the operation, patients were divided into two groups, a reconstructed titanium plate fixation (RPF) group (n = 28) and a conventional titanium plate fixation (CPF) group (n = 31). Improvements in neurological function, cervical range of motion (ROM), cervical curvature index (CCI), preservation of posterior cervical muscle mass, and axial symptoms were compared between the two groups. Results There were no significant differences in operative time and intraoperative blood loss between the groups (p > 0.05). The Japanese Orthopaedic Association (JOA) score significantly increased in both groups postsurgery (p < 0.05); the neurological recovery rate was similar between the two groups (64.1 ± 13.3% vs. 65.9 ± 14.7%, p > 0.05). There was no significant loss of cervical ROM in either group (p > 0.05). The anteroposterior dural sac diameter at the C2 level was significantly enlarged in both groups (p < 0.05). Alternatively, CCI was significantly reduced in the CRP group (p < 0.05) but unchanged in the RPF group (p > 0.05). The cross-sectional area of the posterior cervical muscles was also significantly reduced in the CPF group (p < 0.05) but maintained in the RPF group (p > 0.05). Finally, axial symptoms were more severe in the CPF group than in the RPF group (p < 0.05). Conclusion Laminoplasty is an effective surgical procedure for CSM involving the C2 segment. The reconstructed titanium plate achieved superior maintenance of cervical curvature and reduced both muscle atrophy and severity of axial symptoms compared with titanium conventional plates.

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Exact solution by dynamic stiffness method for the natural vibration of porous functionally graded plate considering neutral surface

Proceedings of the Institution of Mechanical Engineers Part L Journal of Materials Design and Applications ◽

10.1177/1464420720988170 ◽

2021 ◽

pp. 146442072098817

Author(s):

Md. Imran Ali ◽

Mohammad Sikandar Azam

Keyword(s):

Power Law ◽

Functionally Graded Material ◽

Stiffness Matrix ◽

Natural Vibration ◽

Dynamic Stiffness ◽

Functionally Graded ◽

Neutral Surface ◽

Functionally Graded Plate ◽

Dynamic Stiffness Matrix ◽

Graded Material

This paper presents the formulation of dynamic stiffness matrix for the natural vibration analysis of porous power-law functionally graded Levy-type plate. In the process of formulating the dynamic stiffness matrix, Kirchhoff-Love plate theory in tandem with the notion of neutral surface has been taken on board. The developed dynamic stiffness matrix, a transcendental function of frequency, has been solved through the Wittrick–Williams algorithm. Hamilton’s principle is used to obtain the equation of motion and associated natural boundary conditions of porous power-law functionally graded plate. The variation across the thickness of the functionally graded plate’s material properties follows the power-law function. During the fabrication process, the microvoids and pores develop in functionally graded material plates. Three types of porosity distributions are considered in this article: even, uneven, and logarithmic. The eigenvalues computed by the dynamic stiffness matrix using Wittrick–Williams algorithm for isotropic, power-law functionally graded, and porous power-law functionally graded plate are juxtaposed with previously referred results, and good agreement is found. The significance of various parameters of plate vis-à-vis aspect ratio ( L/b), boundary conditions, volume fraction index ( p), porosity parameter ( e), and porosity distribution on the eigenvalues of the porous power-law functionally graded plate is examined. The effect of material density ratio and Young’s modulus ratio on the natural vibration of porous power-law functionally graded plate is also explained in this article. The results also prove that the method provided in the present work is highly accurate and computationally efficient and could be confidently used as a reference for further study of porous functionally graded material plate.

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Notice of Retraction: Reliability Sensitivity Analysis for Dynamic Stiffness of Motor Spindles in a Machining Center

IEEE Access ◽

10.1109/access.2021.3108215 ◽

2021 ◽

pp. 1-1

Author(s):

Ying Du ◽

Haitao Xu ◽

Shengxi Zhou

Keyword(s):

Sensitivity Analysis ◽

Dynamic Stiffness ◽

Machining Center ◽

Reliability Sensitivity ◽

Reliability Sensitivity Analysis

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Design and analysis of a vibration isolation system with cam–roller–spring–rod mechanism

Journal of Vibration and Control ◽

10.1177/10775463211000516 ◽

2021 ◽

pp. 107754632110005

Author(s):

Yonglei Zhang ◽

Guo Wei ◽

Hao Wen ◽

Dongping Jin ◽

Haiyan Hu

Keyword(s):

Vibration Isolation ◽

Dynamic Stiffness ◽

Experimental Studies ◽

Excitation Amplitude ◽

Isolation System ◽

Vibration Isolation System ◽

Stiffness Characteristic ◽

Negative Stiffness Mechanism ◽

Isolation Systems ◽

Vibration Isolation Performance

The vibration isolation system using a pair of oblique springs or a spring-rod mechanism as a negative stiffness mechanism exhibits a high-static low-dynamic stiffness characteristic and a nonlinear jump phenomenon when the system damping is light and the excitation amplitude is large. It is possible to remove the jump via adjusting the end trajectories of the above springs or rods. To realize this idea, the article presents a vibration isolation system with a cam–roller–spring–rod mechanism and gives the detailed numerical and experimental studies on the effects of the above mechanism on the vibration isolation performance. The comparative studies demonstrate that the vibration isolation system proposed works well and outperforms some other vibration isolation systems.

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Concrete Strength and Deformation Property under Sea Water Erosion Environment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.446-449.2554 ◽

2012 ◽

Vol 446-449 ◽

pp. 2554-2559 ◽

Cited By ~ 1

Author(s):

Jian Jun Cai ◽

Feng Zhang ◽

Wei Cui ◽

Shou Shan Chen ◽

Pu Lun Liu

Keyword(s):

Large Scale ◽

Failure Modes ◽

Deformation Property ◽

Sea Water ◽

Dynamic Stiffness ◽

Concrete Strength ◽

Strain Curve ◽

Water Erosion ◽

Strength And Deformation ◽

Erosion Environment

In order to effectively assess the concrete strength and deformation property under sea water erosion environment, concrete stress and strain curve was researched with the number of wet and dry cycle of 0 times, 10 times , 20 times, 30 times, 40 times, 50 times and 60 times based on the large-scale static and dynamic stiffness servo test set. The stress - strain curves of concrete was tested for the lateral pressure 10.8MPa, 14.4MPa, and 18.8MPa at different dry-wet cycles, The failure modes and superficial cracking characteristics of specimens are reported at different dry-wet cycles. Concrete elastic modulus and compressive strength were researched. Based on concrete mechanical theory , the classic Kufer-Gerstle strength criteria of concrete was used, a large number of test samples of multivariate data were nonlinear regressed, a biaxial concrete strength criterion was established taking into account the stress ratio and the number of dry-wet cycles.

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