scholarly journals Stiffness Evaluation and fast matching method of mechanical composite structure

2021 ◽  
Vol 2093 (1) ◽  
pp. 012015
Author(s):  
Jishuang Lv
Keyword(s):  
Composite Structure ◽  
Evaluation Method ◽  
Dynamic Stiffness ◽  
Static Stiffness ◽  
Matching Method ◽  
Main Bearing ◽  
Characterization Methods ◽  
Element Simulation ◽  
Stiffness Evaluation ◽  
Bearing Cap

Abstract Stiffness evaluation can improve the reliability and safety of combined machinery, which is often used to evaluate the performance of combined machinery. In order to study the stiffness evaluation method and rapid matching of mechanical composite structure, the composite machinery composed of high-power diesel is taken as the research object. The results show that the error between test mode and calculation mode is no more than 10%, indicating the reliability of finite element simulation model; two characterization methods of static stiffness and dynamic stiffness are determined, and the analysis methods of two characterization methods of combined machinery are discussed one by one. Taking the combined machinery of body, main bearing cap and oil pan as the research object, the overall stiffness characterization data of three parts are obtained one by one; finally, the principles of mechanical combination Stiffness Evaluation and rapid matching are summarized. This study provides a reference for Stiffness Evaluation and rapid matching of combined mechanical structures.

scholarly journals A New Efficient Stiffness Evaluation Method to Improve Accuracy of Hexapods

2018 ◽  
Author(s):  
Vinayak J. Kalas ◽  
Alain Vissière ◽  
Thierry Roux ◽  
Olivier Company ◽  
Sébastien Krut ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Positioning System ◽  
Positioning Error ◽  
Stiffness Parameter ◽  
Positioning Accuracy ◽  
Stiffness Evaluation ◽  
Improve Accuracy ◽  
Identification Technique ◽  
Six Degree Of Freedom ◽  
Structural Compliance

Structural compliance of hexapods limits their positioning accuracy. Taking a step towards solving this problem, this paper proposes a new efficient method to evaluate the stiffness of hexapods in order to predict and correct their positioning error due to compliance. The proposed method can be used to predict the six degree of freedom deflection of the platform under load. This method uses a simple lumped stiffness parameter model whose parameters can be estimated using the identification technique presented in this paper. An experimental study with micrometer level measurements performed on a hexapod based micro-positioning system is used to assess the efficiency of the presented method.

Manufacturing Error Detection in Plate and Cylindrical Composite Structures

2020 ◽  
Author(s):  
Cihan Talebi ◽  
Bülent Acar ◽  
Gökhan O. Özgen
Keyword(s):  
Error Detection ◽  
Composite Structure ◽  
Composite Structures ◽  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Element Model ◽  
Mode Shapes ◽  
Fiber System ◽  
Error Identification ◽  
Manufacturing Error

Abstract Due to their superior weight to strength ratio of composites to common metallic structures, composite technology is widely used in aerospace industry. Assessment of damage in composites has gained interest after a large number of accidents caused by unanticipated damages in the composite structures. Many different structural health monitoring applications were developed over the years due to the fact that composite materials may inherit damage from within, not always visible from surface. The most common types of errors encountered in the industry are due to misaligned fibers, a mix-up in ply order, and delaminations: all presenting changes in the vibro-acoustical performance of the composite structure. This paper discusses the change in the dynamic properties of a composite structure contains a manufacturing error such as a ply lay-up error, and a ply angle error. Both plate and cylindrical structure types were considered for the stated error types. Effect of symmetric errors, unsymmetrical and unbalanced errors, and mid-plane errors were considered in the case of ply orientations, and dynamic stiffness matrix was used to identify the error. Identification of the structure’s layup properties and manufacturing error identification is employed. From the measured modal properties of the structure, a back-tracking strategy was used to generate the ply lay-up of the composite structure. Prepreg plates of a single carbon fiber system and filament wound hybrid cylinders consisting of glass and carbon fibers were manufactured for testing. Modal tests on plates and cylindrical composite structures were performed and compared with the analysis. A good match between the finite element model and experiment was shown in natural frequencies and mode shapes.

scholarly journals A Full-Scale Experimental Study of the Vertical Dynamic and Static Behavior of the Pier-Cap-Pile System

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Jianlei Liu ◽  
Meng Ma ◽  
Flavio Stochino
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Dynamic Stiffness ◽  
Soil Layer ◽  
Low Frequency ◽  
Full Scale ◽  
Single Pile ◽  
Static Stiffness ◽  
Loading Test ◽  
Test Technique

The bearing capacity evaluation of bridge substructures is difficult as the static loading test (SLT) cannot be employed for the bridges in services. As a type of dynamic nondestructive test technique, the dynamic transient response method (TRM) could be employed to estimate the vertical bearing capacity when the relationship between static stiffness and dynamic stiffness is known. The TRM is usually employed to evaluate single piles. For the pier-cap-pile system, its applicability should be investigated. In the present study, a novel full-scale experimental study, including both TRM test and SLT, was performed on an abandoned bridge pier with grouped pile foundation. The test included three steps: firstly, testing the intact pier-cap-pile system; then, cutting off the pier and testing the cap-pile system; finally, cutting off the cap and testing the single pile. The TRM test was repeatedly performed in the above three steps, whereas the SLT was only performed on the cap-pile system. Based on the experimental results, the ratio of dynamic and static stiffness of the cap-pile system was obtained. The results show that (1) in the low-frequency range (between 10 and 30 Hz in this study), the dynamic stiffness of the whole system is approximately four times of that of a single pile; (2) the ratio of dynamic and static stiffness of the cap-pile system tested in the study is approximately 1.74, which was similar to other tested values of a single pile; (3) to evaluate the capacity of similar cap-pile system and with similar soil layer conditions by TRM, the value of Kd/Ks tested in the study can be used as a reference.

Die Design for Main Bearing Cap of Engine Block Based Semi-Solid Die Casting Process and the Comparison Analysis with Squeeze Casting Process

2019 ◽  
Vol 285 ◽  
pp. 429-435 ◽  
Author(s):  
Song Chen ◽  
Da Quan Li ◽  
Fan Zhang ◽  
Min Luo ◽  
Xiao Kang Liang ◽  
...  
Keyword(s):  
Squeeze Casting ◽  
Die Casting ◽  
Dendritic Structure ◽  
Casting Process ◽  
Die Design ◽  
Main Bearing ◽  
Block Based ◽  
Semi Solid ◽  
Bearing Cap ◽  
Squeeze Casting Process

There are two new processes to development automobile structural components which have certain thickness. In the present paper, taking a main bearing cap product as an example, analyses die design by comparing the experimental and computational numerical simulation results. For the main bearing cap, product structure and mold design were designed to be suitable for characters of SSM die casting and squeeze process. Semi-solid slurry has significantly higher viscosity than liquid metal. This character of fluidity and solid fraction phase make the flow condition more laminar than liquid squeeze casting with the partial fill experiment. And compared with squeeze casting process, the globular shape grain size is smaller than dendritic structure. And mechanical property result shows that the elongation of SSM die casting can achieve more than twice than squeeze casting.

scholarly journals Nonlinear Static and Dynamic Stiffness Characteristics of Support Hydraulic System of TBM

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Jianfeng Tao ◽  
Junbo Lei ◽  
Chengliang Liu ◽  
Wei Yuan
Keyword(s):  
Hydraulic System ◽  
Vibrational Energy ◽  
Dynamic Stiffness ◽  
Operating Conditions ◽  
Static Stiffness ◽  
Railway Tunnel ◽  
Relief Valve ◽  
Component Structure ◽  
Stiffness Characteristics ◽  
Stable Stage

AbstractFull-face hard rock tunnel boring machines (TBM) are essential equipment in highway and railway tunnel engineering construction. During the tunneling process, TBM have serious vibrations, which can damage some of its key components. The support system,an important part of TBM, is one path through which vibrational energy from the cutter head is transmitted. To reduce the vibration of support systems of TBM during the excavation process, based on the structural features of the support hydraulic system, a nonlinear dynamical model of support hydraulic systems of TBM is established. The influences of the component structure parameters and operating conditions parameters on the stiffness characteristics of the support hydraulic system are analyzed. The analysis results indicate that the static stiffness of the support hydraulic system consists of an increase stage, stable stage and decrease stage. The static stiffness value increases with an increase in the clearances. The pre-compression length of the spring in the relief valve affects the range of the stable stage of the static stiffness, and it does not affect the static stiffness value. The dynamic stiffness of the support hydraulic system consists of a U-shape and reverse U-shape. The bottom value of the U-shape increases with the amplitude and frequency of the external force acting on the cylinder body, however, the top value of the reverse U-shape remains constant. This study instructs how to design the support hydraulic system of TBM.

A Novel Fatigue Evaluation Approach with Direct Steady Cycle Analysis (DSCA) Based on the Linear Matching Method (LMM)

2019 ◽  
Vol 795 ◽  
pp. 383-388 ◽  
Author(s):  
Xiao Tao Zheng ◽  
Zhi Yuan Ma ◽  
Hao Feng Chen ◽  
Jun Shen
Keyword(s):  
Fatigue Life ◽  
Evaluation Method ◽  
Low Cycle Fatigue ◽  
Effective Strain ◽  
Strain Range ◽  
Matching Method ◽  
Evaluation Approach ◽  
Perfectly Plastic ◽  
Fatigue Evaluation ◽  
Linear Matching Method

The traditional Low Cycle Fatigue (LCF) evaluation method is based on elastic analysis with Neuber’s rule which is usually considered to be over conservative. However, the effective strain range at the steady cycle should be calculated by detailed cycle-by-cycle analysis for the alternative elastic-plastic method in ASME VIII-2, which is obviously time-consuming. A Direct Steady Cycle Analysis (DSCA) method within the Linear Matching Method (LMM) framework is proposed to assess the fatigue life accurately and efficiently for components with arbitrary geometries and cyclic loads. Temperature-dependent stress-strain relationships considering the strain hardening described by the Ramberg-Osgood (RO) formula are discussed and compared with those results obtained by the Elastic-Perfectly Plastic (EPP) model. Additionally, a Reversed Plasticity Domain Method (RPDM) based on the shakedown and ratchet limit analysis method and the DSCA approach within the LMM framework (LMM DSCA) is recommended to design cyclic load levels of LCF experiments with predefined fatigue life ranges.

Experimental Study on the Performance of the Laminated Steel Isolators

2013 ◽  
Vol 423-426 ◽  
pp. 1603-1607
Author(s):  
Yao Guo Xie ◽  
Ping He ◽  
Xian Qiang Qu ◽  
Hong Bin Cui
Keyword(s):  
Experimental Study ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Performance Testing ◽  
Stiffness Ratio ◽  
Static Stiffness ◽  
Comparison Of The Results

Through the analysis and comparison of the results of static and dynamic performance testing of a series of laminated steel pieces isolators used in the vibration isolation of warships, in the number and thickness of laminated steel pieces of the same circumstances, laminated steel arc and preload of test samples had a certain impact on the values ​​of static stiffness, dynamic stiffness, damping ratio as well as dynamic and static stiffness ratio.

Research on Chromaticity Characterization Methods of the Ink Trapping

2012 ◽  
Vol 262 ◽  
pp. 113-118 ◽  
Author(s):  
Jiang Hao Liu ◽  
Shao Hong Gao
Keyword(s):  
Evaluation Method ◽  
Density Measurement ◽  
Color Difference ◽  
Characterization Methods ◽  
Advantages And Disadvantages ◽  
Density Evaluation ◽  
Color Printing ◽  
Color Value ◽  
The Ideal ◽  
Trapping Effects

The practical applied formula are based on the density measurement in ink trapping characterization methods, but the density measurement is more suitable for detecting single color printing effect. Due to the defects of the testing equipment, the density measurement is not suitable for the evaluation of ink trapping. Chromaticity evaluation method bases on the color difference between the sample color values and the ideal color values to evaluate ink trapping effects, which can characterize better on the ink trapping effects. Research results showed that the density evaluation method has many deficiencies, and Neugebauer equations predict on the chroma evaluation method doesn’t reach an enough precise to get the ideal value about the secondary overprinting, while the color value which is measured by spectroscopic measurement by experimental methods can be used as the ideal color value of the chromaticity evaluation method. Study on the comparison between density evaluation method and chroma evaluation method of ink trapping, the relative conclusions about advantages and disadvantages of different ink trapping characterization methods will be summarized.

Analysis of Fretting Behavior for Fasten Surface between Diesel Engine Cylinder Block and Main Bearing Cap

2012 ◽  
Vol 479-481 ◽  
pp. 986-989
Author(s):  
Wen Li ◽  
Ri Dong Liao ◽  
Zheng Xing Zuo
Keyword(s):  
Diesel Engine ◽  
Crack Initiation ◽  
Load Condition ◽  
Location Parameter ◽  
Fretting Fatigue ◽  
Cylinder Block ◽  
Main Bearing ◽  
Rotating Speed ◽  
Engine Cylinder ◽  
Bearing Cap

Fretting fatigue becomes a typical failure mode for engine cylinder block caused by the increasing of the gas pressure and rotating speed, but the mechanism of fretting fatigue under diesel engine load condition hasn’t been systematic studied. In this paper, the fretting behaviors are mainly discussed by using fretting friction work parameter W and crack initiation location parameter G.

Sign in / Sign up

Export Citation Format

Share Document