scholarly journals IDENTIFICATION OF DAMAGED ZONES IN C/PPS SPECIMENS SUBJECTED TO FATIGUE LOADING BASED ON HIGH-RESOLUTION THERMOGRAPHY

2016 ◽  
Vol 3 ◽  
pp. 35-38
Author(s):  
Petr Koudelka ◽  
Daniel Kytýř ◽  
Nela Fenclová ◽  
Martin Šperl
Keyword(s):  
High Resolution ◽  
Impact Damage ◽  
Fiber Composite ◽  
Fatigue Loading ◽  
Polyphenylene Sulfide ◽  
Tensile Fatigue ◽  
Segmented Images ◽  
Heated Area ◽  
Number Of Cycles ◽  
Processing Techniques

In this study high resolution thermography is used for identification of damaged zones in Carbon fiber/polyphenylene sulfide (C/PPS) long fiber composite specimens with induced impact damage subjected to tensile fatigue loading. Image processing techniques were applied on thermographs from all loading cases to obtain segmented images of the damaged location that were then used for calculation of the heated area. Results show that the considered method can be used to identify heated area in the vicinity of damage with high confidence at low number of cycles where no significant fatigue effect is present in the material.

scholarly journals DAMAGE PROPAGATION AND THERMOGRAPHY IN DISCONTINUOUS CARBON FIBER COMPOSITE (DCFC) UNDER TENSILE (FATIGUE) LOADING

2019 ◽  
Vol 82 (1) ◽  
Author(s):  
Jefri Bale ◽  
Emmanuel Valot ◽  
Olivier Polit
Keyword(s):  
Fatigue Life ◽  
Carbon Fiber ◽  
Fiber Composite ◽  
Thermal Response ◽  
Fatigue Loading ◽  
Carbon Fiber Composite ◽  
Damage Propagation ◽  
Initial Damage ◽  
Tensile Fatigue ◽  
Non Destructive

The discontinuous carbon fiber composite (DCFC) has a different damage behaviour due to non homogenuous sub structure. Consequently, monitoring and diagnosis of DCFC damage mechanisms require the application of a contactless method in real-time operation, i.e., non destructive method of thermography. The aim of this study is to investigate the damage propagation of DCFC material under tensile (fatigue) condition with non destructive testing (NDT) thermography method. Under fatigue testing, temperature evolutions were monitored by an Infra-Red (IR) camera. The results show that damage propagation and thermal response indicated the similar behaviour which consists of three stages. At the beginning, low temperature increased until ≈ 10% of fatigue life due to the initial damage. The initial damage propagated and the temperature reached the stable thermal state due to the saturation in the damage appearance of micro cracking of matrix and chip until ≈ 80% of fatigue life. At the last ≈ 20% of fatigue life, damage continued to propagate and provoked the occurrence of macro damage that induced the final failure indicated by highest peak of temperature. The analysis from the experiment results concluded that thermal response relates with the damage propagation of DCFC under fatigue loading.

Tomography Observation of Fiber Reinforced Composites after Fatigue Testing

2015 ◽  
Vol 799-800 ◽  
pp. 937-941
Author(s):  
Jefri Bale ◽  
Emmanuel Valot ◽  
Martine Monin ◽  
Olivier Polit ◽  
Claude Bathias ◽  
...  
Keyword(s):  
Fatigue Testing ◽  
Fiber Composite ◽  
Fatigue Loading ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Destructive Testing ◽  
Carbon Fiber Composite ◽  
Glass Fiber Composite ◽  
Tensile Fatigue

This work presented an experimental study to observe the inside conditions and damage appearances of fiber reinforced composites material by non destructive testing (NDT) method. In order to achieve this, an open hole specimen of unidirectional glass fiber composite (GFRP) and discontinuous carbon fiber composite (DCFC) had been using as the specimen test under tensile fatigue loading and observed using post failure monitoring techniques of NDT namely computed tomography (CT) scan. The results shown that the tomography observation based on segmentation method of gray value gives a good detection on early damage appearances before final failure of GFRP and DCFC after tensile fatigue loading conditions.

scholarly journals Theoretical and Experimental Fatigue Strength Calculations of Lips Compensating Circumferential Backlash in Gear Pumps

Energies ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 251
Author(s):  
Piotr Osiński ◽  
Grzegorz Chruścielski ◽  
Leszek Korusiewicz
Keyword(s):  
Maximum Stress ◽  
Theoretical Calculations ◽  
Fatigue Loading ◽  
Minimum Thickness ◽  
Bending Tests ◽  
External Gear Pumps ◽  
Gear Pumps ◽  
In Series ◽  
Number Of Cycles ◽  
Technical Solutions

This article presents theoretical and experimental calculations of the minimum thickness of a compensation lip used in external gear pumps. Pumps of this type are innovative technical solutions in which circumferential backlash (clearance) compensation is used to improve their volumetric and overall efficiency. However, constructing a prototype of such a pump requires long-lasting research, and the compensation lip is its key object, due to the fact that it is an element influenced by a notch and that it operates in unfavorable conditions of strong fatigue stresses. The theoretical calculations presented in this article are based on identifying maximum stress values in a fatigue cycle and on implementing the stress failure condition and the conditions related to the required value of the fatigue safety factor. The experimental research focuses on static bending tests of the lips as well as on the fatigue loading of the lips in series of tests at increasing stress values until lip failure due to fatigue. The tests allowed the minimum lip thickness to be found for the assumed number of fatigue cycles, which is 2.5 times the number of cycles used in wear margin tests.

Study of the low cycle fatigue of 12Cr18Ni10Ti steel based on fractal analysis and artificial intelligence approaches

2021 ◽  
Vol 87 (9) ◽  
pp. 59-67
Author(s):  
A. A. Khlybov ◽  
Yu. G. Kabaldin ◽  
M. S. Anosov ◽  
D. A. Ryabov ◽  
D. A. Shatagin
Keyword(s):  
Neural Network ◽  
Growth Rate ◽  
Fractal Dimension ◽  
Low Temperatures ◽  
Main Crack ◽  
Fatigue Loading ◽  
Wide Range ◽  
Lower Temperature ◽  
Number Of Cycles ◽  
Dimension Index

The evolution of the structure and assessment of the age limit of steel 12Cr18Ni10Ti upon fatigue loading is considered using neural network modeling and approaches of fractal analysis of the microstructure. An algorithm for processing images of the microstructures has been developed to improve their quality. An indicator of the fractal dimension of the image is used as a quantitative indicator for assessing the evolution of the microstructure of the surface metal layer. A quantitative assessment of the structures at different stress amplitudes is carried out in a wide range of low temperatures using the fractal dimension index. Correlation of the fractal dimension index with the run of the sample material is shown. The appearance of the main crack was observed in the range of 0.7 - 0.8 from the number of cycles to failure, after which the crack growth rate increased. At a lower temperature, the main crack is formed later, but further loading results in a higher crack growth rate. Formation of the secondary phases in austenitic steel at a lower temperature occurred at earlier stages than that at a temperature of t = +20°C, which led to hardening of the material. An artificial neural network (ANN) has been developed and trained for assessing structural changes in metal proceeding from the fractal dimensionality of the microstructure images at different stages of fatigue loading. The developed neural network made it possible to estimate with a sufficiently high accuracy the number of cycles before damage of the sample and the residual life of the material. Thus, the developed ANN can be used to assess the current state of the material in a wide range of low temperatures.

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