scholarly journals Deformation Properties of Railroad Ballast Subjected to Cyclic Loading and Evaluation Method

2002 ◽  
Vol 5 ◽  
pp. 793-800 ◽  
Author(s):  
Akira NAMURA ◽  
Yukihiro KOHATA ◽  
Seiichi MIURA
Keyword(s):  
Cyclic Loading ◽  
Evaluation Method ◽  
Deformation Properties

Effect of Pre-Strain on Fatigue Behaviour of AZ31 Mg Alloy

2012 ◽  
Vol 706-709 ◽  
pp. 3052-3056
Author(s):  
Gao Feng Quan ◽  
Ying Bo Zhang ◽  
Zhao Ming Liu
Keyword(s):  
Fatigue Life ◽  
Cyclic Loading ◽  
Evaluation Method ◽  
Fatigue Cracks ◽  
Fatigue Property ◽  
Fatigue Behaviour ◽  
Sem Analysis ◽  
Fatigue Tests ◽  
Mg Alloys ◽  
Critical Feature

Mg Alloys Are the Lightest Structural Alloys with Excellent Castability and Machinability as Well as Highest Specific Strength and Stiffness. According to their Hexagonal close Packed Crystal Lattice there Is an Urgent Requirement of Mechanical Property Evaluation Method for Industrial Application, Particularly to Wrought Mg Alloys. Cyclic Loading Is a Very Popular Mode for Most Structural Application Situations. Recent Development of Fatigue Examination of Extruded Profile Has Shown that Mg Alloys Show Not so Ideal Fatigue Property. so that the Further Detailed Study on Cyclic Loading for Plastic Deformed Mg Alloys Is Needed. Tension-Tension Fatigue Tests Were Conducted on Pre-Strained AZ31 Mg Alloys that Produced by Rolling and Extruding Procedures. the Results Show that the Compressive Plastic Deformation Leads to Reduction of Fatigue Life/limit Significantly. SEM Analysis on Fatigue Fracture Surfaces Indicates that the Fatigue Cracks Initiate in the Surface or Sub-Surface of Dramatically Deformed Zones. the Microstructure Analysis Reveals that the Pre-Strain Brings More Abundant Twinning Bands with the Increase in Pre-Strain. the Decrease in Fatigue Life Demonstrates Also some Critical Feature with the Pre-Strain Level.

In situ characterization of the morphological wrinkling of woven fibrous materials by a mechanical test

2020 ◽  
Vol 90 (17-18) ◽  
pp. 2085-2096 ◽  
Author(s):  
Xiaorui Hu ◽  
Fengxin Sun ◽  
Qicai Wang ◽  
Weidong Gao
Keyword(s):  
Clustering Algorithm ◽  
Evaluation Method ◽  
Mechanical Test ◽  
Subjective Evaluation ◽  
Potential Method ◽  
Industrial Applications ◽  
Woven Fabrics ◽  
Fibrous Materials ◽  
Characteristic Parameters ◽  
Deformation Properties

Wrinkling is one of the most common flaws of woven fabrics in domestic use and industrial applications. It is necessary to develop an objective evaluation method to quantify the smoothness appearance of fabrics effectively. Herein, a fabric multi-deformation tester (FMDT) was designed to evaluate the smoothness appearance of garment fabrics by one sequential mechanical test, overcoming the main difficulties of the existing visual measurement methods for wrinkling evaluation of fabrics with complex colors and patterns. The k-means clustering algorithm was used to objectively cluster the fabric samples based on the characteristic parameters, including the wrinkle-induced residual force ( F wr), hysteresis distance ( H fr), position deflection ( D fr) and stretching recovery slope ( S tr), from the testing curve and the thickness and weight of fabrics, and comparisons with subjective evaluation were also conducted. The results reveal that the k-means clustering is able to classify the smoothness appearance of fabrics using the selected characteristic parameters, showing a good consistency with the subjective clustering results. The feasibility of using the mechanical and deformation properties of textiles to characterize fabric smoothness appearance is proved, and the FMDT provides a potential method to analyze the wrinkling of fibrous materials in a convenient way.

Biaxial Ratchetting Deformation of Solders Considering Halt Conditions

2016 ◽  
Vol 725 ◽  
pp. 299-304
Author(s):  
Yusuke Tomizawa ◽  
Takehito Suzuki ◽  
Katsuhiko Sasaki ◽  
Ken-Ichi Ohguchi ◽  
Daisuke Echizenya
Keyword(s):  
Cyclic Loading ◽  
Evaluation Method ◽  
Solder Joints ◽  
Testing Machine ◽  
Tensile Load ◽  
Tubular Specimen ◽  
Electronic Products ◽  
Accurate Evaluation ◽  
Joint Specimen ◽  
Limit Test

Recently, Halt (Highly accelerated limit test) is widely employed for evaluation of reliability of electronic products. Halt condition is quite severe. The tested products are subjected to mechanical impacts, thermal shock, and vibration at same time. However, there has not been a reasonable and accurate evaluation method for Halt yet. To construct an accurate evaluation method of Halt, basic deformation mechanism of parts of the electronic products should be clarified from both experimental and theoretical points of view. In this paper, focusing on solder joints of circuit boards of electronic products, ratchetting deformation, especially, biaxial ratchetting deformation of solder joints is revealed from both experimentally and theoretically. The authors have already conducted biaxial ratchetting test combining axial and torsional cyclic loading using a tubular specimen of Type 304 stainless steel. However, as for solders, it is difficult to make tubular specimen. Since size of the solder joints is micron, a small size joint specimen of copper tube and solder is employed in this paper. First, to confirm the quality of the joint specimen such as boundary between copper and solder, both the tensile and cyclic loading tests are conducted at several temperatures using Sn-3Ag-0.5Cu. The basic characteristic of tensile and fatigue failure is obtained from these tests. After the confirmation of the accuracy of the joint specimen, biaxial ratchetting tests are conducted superposing the tensile load on cyclic torsion. The biaxial ratchetting tests are conducted using a biaxial loading testing machine developed for the joint specimens of solder and copper.

Research on the Stability of Thermal Barrier Coatings under Thermal Cyclic Loading

2017 ◽  
Vol 730 ◽  
pp. 75-80 ◽  
Author(s):  
Jian Sun ◽  
Ying Qiang Xu ◽  
Wan Zhong Li ◽  
Kai Lv
Keyword(s):  
Cyclic Loading ◽  
Stress Field ◽  
Evaluation Method ◽  
Thermally Grown Oxide ◽  
Interfacial Stress ◽  
Thermal Barrier ◽  
Fea Model ◽  
Barrier Coating ◽  
The Stability ◽  
Evolution Behavior

Thermal barrier coating systems (TBCs) are widely used in turbines. However, premature failures have impaired the use of TBCs and cut down their lifetime. The thermally grown oxide layer (TGO) thickening and the material thermal expansion misfit under thermal cyclic loading significantly affect the interfacial stress field and stability of TBCs. In this study, the stability evaluation method of TBCs under thermal cyclic loading based on energy is established using the visco-elastoplastic and shakedown theorem. The semicircular shape interface is used to simplify the complicated interfacial undulations in FEA model. And actual TGO thickness obtained from experiment is used to simulate the bond coat oxidation. Then the effect of TGO thickening on the stability and stress field of TBCs under thermal cyclic loading is analyzed through the numerical simulation. It is concluded that estimating from the stress-strain evolution behavior, the local stability of the TBCs decreases with the TGO thickening, and assessing from energy, TBCs shows instable with TGO thickening.

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