Fatigue behavior of 2.5D woven composites based on the first-order bending vibration tests

2022 ◽  
pp. 115218
Author(s):  
Yana Wang ◽  
Yu Gong ◽  
Qin Zhang ◽  
Yuhuai He ◽  
Zhanfang Liu ◽  
...  
Keyword(s):  
Fatigue Behavior ◽  
Woven Composites ◽  
Bending Vibration ◽  
First Order ◽  
Vibration Tests

scholarly journals Effect of the Supports’ Positions on the Vibration Characteristics of a Flexible Rotor Shafting

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Miaomiao Li ◽  
Zhuo Li ◽  
Liangliang Ma ◽  
Rupeng Zhu ◽  
Xizhi Ma
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Vibration Characteristics ◽  
Rotor System ◽  
Experimental Investigations ◽  
Flexible Rotor ◽  
Bending Vibration ◽  
First Order ◽  
Element Simulation

In this study, we evaluated the effect of changing supports’ position on the vibration characteristics of a three-support flexible rotor shafting. This dependency was first analyzed using a finite element simulation and then backed up with experimental investigations. By computing a simplified rotor shafting model, we found that the first-order bending vibration in a forward whirl mode is the most relevant deforming mode. Hence, the effect of the supports’ positions on this vibration was intensively investigated using simulations and verified experimentally with a house-made shafting rotor system. The results demonstrated that the interaction between different supports can influence the overall vibration deformation and that the position of the support closer to the rotor has the greatest influence.

Effect of the Ratio between Tension and Bending Vibration Loads on the Fatigue Behavior and Failure Mode of Titanium Alloy TA11

2014 ◽  
Vol 898 ◽  
pp. 27-32
Author(s):  
Nan Ma ◽  
Xin Ling Liu ◽  
Zhi Wang Qiu ◽  
Yu Huai He ◽  
Chun Hu Tao ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Failure Mode ◽  
Failure Modes ◽  
Fatigue Behavior ◽  
Tensile Force ◽  
Fatigue Properties ◽  
Bending Vibration ◽  
Transversal Vibration ◽  
Axial Tensile ◽  
Vibration Loads

This paper studied the effect of the ratio between the axial tensile force and the transversal vibration loads on the fatigue behavior and failure mode of the near alpha titanium alloy TA11, to simulate the service stress state applied on the engine blades, where a large centrifugal force is superimposed with bending vibration loads. The plate-like specimens were used in the fatigue tests by a special testing device which was designed and fabricated in the present research,where the vibration loads were applied by the electro-magnetic exciters. By experiments under various multi-axial fatigue loading cases with different ratios between the axial tensile force and the transversal vibration loads, the fatigue behavior and failure modes were observed and compared. Then, the energy based fatigue criteria were applied for correlation of the test results. The fatigue properties of titanium alloy TA11 under the specialized loading conditions are characterized and discussed. In addition, the experimental observations on the vibration behavior superimposed with different magnitude of axial tensile force are also helpful for understanding the real working conditions of the engine blades.

Vibration Tests With a 1/13-Scaled 3-D Model of the Folsom Dam Tainter-Gate and Its Prediction by Theory

2006 ◽  
Author(s):  
Keiko Anami ◽  
Noriaki Ishii ◽  
Charles W. Knisely ◽  
Robert V. Todd ◽  
Tatsuya Oku
Keyword(s):  
Dynamic Instability ◽  
Vibration Test ◽  
Test Results ◽  
Bending Vibration ◽  
Coupled Mode ◽  
Basic Assumptions ◽  
Vibration Tests ◽  
D Model ◽  
Theoretical Analyses ◽  
Made In

This study presents 3-D model gate vibration test results demonstrating violent spontaneous vibrations and validating the basic assumptions made in previously published theoretical analyses. First, the design of a 1/13-scaled 3-D model of Folsom dam Tainter-gate is presented, in which the streamwise natural bending vibration mode of the skinplate, measured in the field vibration tests on the remaining Folsom gate, is shown to be correctly replicated with the aid of FEM simulations. Secondly, in-air and in-water vibration test results with the 1/13-scaled 3-D model are presented, reproducing the intense coupled-mode self-excited vibrations. Thirdly, test results are plotted on a theoretically calculated stability criterion diagram to confirm the validity of the theoretical analysis. Finally, the intense dynamic instability of the Folsom gate, which could have caused its failure, is presented.

Cable Reinforced Small Scale Horizontal Axial Wind Turbine

2013 ◽  
Vol 394 ◽  
pp. 309-313
Author(s):  
Yuan Ma ◽  
Pan Zeng ◽  
Hong Ya Lu ◽  
Yue Jie Xu
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Turbines ◽  
Noise Level ◽  
Wind Turbine Blade ◽  
Small Scale ◽  
Optimum Location ◽  
Reinforcement Structure ◽  
First Order ◽  
Vibration Tests

In this paper, a cable reinforcement structure for small scale horizontal axial wind turbines is proposed. Shock-vibration tests were performed on the cable reinforced structure with different parameters of cable installation. The first order frequency of the blade was chosen to represent the stiffness of the blade rotor. According to the results, an optimum location of cable reinforcement exists at around 1/3 length of the wind turbine blade, and the first order frequency of the blade rotor will rise with the tension of the cable in a certain range. Further analysis showed that besides improving the reliability of the wind turbine rotors, the cable reinforcement structure also provides a possibility to use cheaper materials for blade manufacturing and also control the noise level of small scale horizontal axial wind turbines.

scholarly journals A New Insight to Vibration Characteristics of Spans under Random Moving Load: Case Study of 38 Bridges in Ho Chi Minh City, Vietnam

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Thanh Q. Nguyen ◽  
Thao D. Nguyen ◽  
Lam Q. Tran ◽  
Nhi K. Ngo
Keyword(s):  
Power Spectrum ◽  
Moving Load ◽  
Power Spectrum Density ◽  
Bending Vibration ◽  
Operational Process ◽  
Torsion Vibration ◽  
Spectrum Density ◽  
Vibration Tests ◽  
High Level

We propose a novel representative power spectrum density as a specific characteristic for showing responses of spans during a long operational period. The idea behind this method is to use the representative power spectrum density as a powerful tool to evaluate the stiffness decline of spans during their operation period. In addition, a new measurement method has been introduced to replace the traditional method of monitoring the health conditions of bridges through a periodic measurement technique. This helps to reduce costs when carrying out testing bridges. Besides, the proposed approach can be widely applied not only in Vietnam but also in many other underprivileged countries around the world. Obtained results show that, during the operational process of spans, there is not only a pure vibration evaluation such as bending vibration and torsion vibration tests but also a combination of various vibration types including bending-torsion vibration or high-level vibrations like first-mode bending and first-mode torsion. Depending on each type of structure and material properties, different types of vibrations will appear more or less during the operational process of spans under a random moving load. Furthermore, the representative power spectrum density is also suitable for evaluating and determining many different fundamental vibrations through the same measurement time as well as various measurement times.

Coupled-Mode Dynamic Instability of Tainter Gates With Parallel Bending Vibration of the Skinplate

2010 ◽  
Author(s):  
Keiko Anami ◽  
Noriaki Ishii ◽  
Takuma Tsuji ◽  
Tatsuya Oku ◽  
Masaru Goto ◽  
...  
Keyword(s):  
Dynamic Instability ◽  
Laboratory Model ◽  
Dynamic Coupling ◽  
Bending Vibration ◽  
Coupled Mode ◽  
Excited Vibration ◽  
Rotational Vibration ◽  
The Usa ◽  
Vibration Mechanism ◽  
Vibration Tests

As part of the investigation of the dynamic instability of the gate closely related to the Folsom Dam Tainter-gate failure, and in order to assure the dynamic stability of the gate, the field vibration tests on three full-scale operational Tainter-gates were conducted. From these tests, the possible existence of another coupled-mode self excited vibration mechanism, which involves the dangerous dynamic coupling of the whole gate rigid-body rotational vibration with a “parallel” bending vibration of the skinplate was suggested. This paper presents the mechanism of the suggested coupled-mode self-excited vibration, theoretical analysis for the suggested dynamic instability, and 2-dimensional laboratory model tests results. Further, the need for retrofit countermeasures for Tainter gates which are currently installed in both Japan and the USA and susceptible to this dangerous coupled-mode dynamic instability is emphasized.

Fatigue Properties of Titanium Alloy TA11 under Multiaxial Loadings with Tension - Bending Vibration

2014 ◽  
Vol 887-888 ◽  
pp. 873-877
Author(s):  
Bin Li ◽  
Nan Ma ◽  
Xin Ling Liu ◽  
Zhi Wang Qiu ◽  
Hong Ren Li
Keyword(s):  
Titanium Alloy ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Loading Conditions ◽  
Test Results ◽  
Bending Vibration ◽  
Alpha Titanium ◽  
Vibration Loads ◽  
Multiaxial Loadings

This paper studied the fatigue behavior of the near alpha titanium alloy TA11 under multiaxial loading conditions with tension - bending vibration, to simulate the service stress state applied on the engine blades, where a large centrifugal force is superimposed with bending vibration loads. A plate-like specimen was used in the fatigue tests with different ratios between the tension and bending vibration loads, then, the energy based fatigue criteria were applied for correlation of the test results. The fatigue properties of titanium alloy TA11 under the specialized loading conditions are characterized and discussed.

Fatigue Behavior of Notched Resin Infusion Molded S2-Glass Twill Woven Composites

1999 ◽  
Author(s):  
Ajit D. Kelkar ◽  
Pramod Chaphalkar
Keyword(s):  
Performance Evaluation ◽  
Fatigue Life ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Fatigue Tests ◽  
Woven Composites ◽  
Resin System ◽  
Woven Composite ◽  
Resin Infusion ◽  
C 50

Abstract The present study provides the performance evaluation of 2 × 2 twill woven composite (S2-Glass and C-50 resin system) material for Integral Armor applications. The laminates were fabricated by using VARIM or RI (Vacuum Assisted Resin Infusion Molding). These components are expected to be under fatigue loading. Fatigue behavior of the unnotched and notched twill woven laminate is presented. Tension-Compression (R = −1) fatigue experiments were performed for both unnotched and notched panels. All the fatigue tests were performed at 1 Hz frequency. S-N diagram and stiffness degradation over the fatigue life of the specimen was obtained.

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