Modelling the Stress Concentration in CFRP at Notches with a Thermally Influenced Cut Edge

2016 ◽  
Vol 1140 ◽  
pp. 288-295 ◽  
Author(s):  
Johannes W. Stock ◽  
Johanna Kerschreiter
Keyword(s):  
Heat Affected Zone ◽  
Laser Cutting ◽  
Thermal Damage ◽  
Fatigue Behaviour ◽  
Positive Influence ◽  
Static Strength ◽  
Measured Temperature ◽  
Cut Edge ◽  
Critical Tension ◽  
Open Hole

The use of higher laser powers in laser cutting of CFRP results in both an increase of productivity and in a growth of the heat affected zone at the cut edge. This thermal damage was related to a loss of the static strength due to the reduce load bearing cross section in various studies. In contrast, the thermal damage caused an increase of the average number of load cycles and to a significant reduction of the deviation among the repetitions of each parameter during dynamic open hole tensile testing in recent studies. To explain this positive influence of laser cutting on the fatigue behaviour of CFRP, an analytical model of the load concentration in a plate with a circular notch could be adapted and modified. The orthotropic property of the material is considered in the model. The static strength of thermally treated CFRP was determined in experiments and applied to the model. By inserting the measured temperature-dependent values of the Young´s modulus, the critical tension at the notch could be determined related to the dimensions of the heat affected zone.

Investigation of cut edge microstructure and surface roughness obtained by laser cutting of titanium alloy Ti-6Al-4V

2021 ◽  
Author(s):  
B. El Aoud ◽  
M. Boujelbene ◽  
A. Boudjemline ◽  
E. Bayraktar ◽  
S. Ben Salem ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Titanium Alloy ◽  
Laser Cutting ◽  
Cut Edge

scholarly journals THE EFFECT OF ENTEROSORPTION AND INTRATISSULAR ELECTROFORESIS OF ANTIBACTERIAL DRUGS ON PROGRESS OF BURN DISEASE

2020 ◽  
pp. 188-192
Author(s):  
B. V. Petriuk ◽  
I. I. Blуk ◽  
О. V. Rоtаr ◽  
L. P. Khomko ◽  
T. A. Petriuk ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Thermal Damage ◽  
Positive Influence ◽  
Reparative Regeneration ◽  
Comprehensive Treatment ◽  
Antibacterial Drugs ◽  
Average Mass ◽  
Thermal Burns ◽  
Burn Disease ◽  
Extensive Burns

Summary. The purpose of our research was to explore the appropriateness of combined usage of enterosorption amplification and intratissular electrophoresis (ITE) of antibiotics in cases of substantial thermal burns. The effect of intratissular electrophoresis (ITE) of antibacterial drugs and enterosorption was studied in 22 patients with dermal thermal burns from 28 to 54 % of their body surface. ITE of antibiotics started from the 3–4 day applying the direct current with density 0,03-0,05 mAh/cm² for 60 min. by the «POTOK-1» device. The authors determined the intoxication degree based on the leukocyte index, the number of average mass molecules and blood plasma electrical conductivity. Also, they observed the course of wound process, conducted bacteriological and cytological researches of the burn wounds in dynamics on 1–3, 6–7, 13–14 and 19–21 days of the burn disease progress. It was found that enterosorption usage in the comprehensive treatment of burn disease allows not only to reduce the level of endogenous intoxication but also to provide an indirect optimizing impact on the progressing of the wound process in the zone of thermal damage, stimulate the reparative regeneration. In the cases with extensive burns, combined usage of the enterosorption detoxification by Enterosgel with the ITE of antibacterial drugs contribute more qualitative positive influence on the wound process and burn disease in general.

Effect of Laser Beam Diameter on Cut Edge of Steel Plates Obtained by Laser Machining

2013 ◽  
Vol 467 ◽  
pp. 227-232 ◽  
Author(s):  
Imed Miraoui ◽  
Mouna Zaied ◽  
Mohamed Boujelbene
Keyword(s):  
Laser Beam ◽  
Laser Cutting ◽  
Steel Plates ◽  
Beam Diameter ◽  
Power Laser ◽  
Laser Beam Diameter ◽  
Machined Surface ◽  
Cut Edge ◽  
Thermal Influence ◽  
Cut Surface

Laser cutting is a thermal process which is used contactless to separate materials. In the present study, high-power laser cutting of steel plates is considered and the thermal influence of laser cutting on the cut edges is examined. The microstructure and the microhardness of the cut edge are affected by the input laser cutting parameter: laser beam diameter. The aim of this work is to investigate the effect of the laser beam diameter on the microhardness beneath the cut surface of steel plates obtained by CO2 laser cutting. The cut surface was studied based on microhardness depth profiles beneath the machined surface. The results show that laser cutting has a thermal effect on the surface microstructure and on the microhardness beneath the cut section. Also the microhardness of the hardening zone depends on the laser beam diameter.

Analysis of Roughness and Heat Affected Zone of Steel Plates Obtained by Laser Cutting

2014 ◽  
Vol 974 ◽  
pp. 169-173 ◽  
Author(s):  
Imed Miraoui ◽  
Mohamed Boujelbene ◽  
Emin Bayraktar
Keyword(s):  
Surface Roughness ◽  
Laser Beam ◽  
Heat Affected Zone ◽  
Laser Power ◽  
Laser Cutting ◽  
Major Effect ◽  
Steel Plates ◽  
Beam Diameter ◽  
Laser Beam Diameter ◽  
Cut Surface

In the present study, high-power CO2 laser cutting of steel plates has been investigated and the effect of the input laser cutting parameters on the cut surface quality is analyzed. The average roughness of the cut surface of the specimens, produced by different laser beam diameter and laser power, were measured by using roughness tester. The scanning electron microscopy SEM is used to record possible metallurgical alterations on the cut edge. The aim of this work is to investigate the effect of laser beam diameter and laser power on the cut surface roughness and on the heat affected zone width HAZ of steel plates obtained by CO2 laser cutting. An overall optimization was applied to find out the optimal cutting setting that would improve the cut surface quality. It was found that laser beam diameter has a negligible effect on surface roughness but laser power had major effect on roughness. The cut surface roughness decreases as laser power increases. Improved surface roughness can be obtained at higher laser power. Also, laser beam diameter and laser power had major effect on HAZ width. It increases as laser power increases.

scholarly journals Effect of Sandblasting on Low and High-Cycle Fatigue Behaviour after Mechanical Cutting of a Twinning-Induced Plasticity Steel

2018 ◽  
Vol 165 ◽  
pp. 18002
Author(s):  
Antoni Lara ◽  
Mercè Roca ◽  
Sergi Parareda ◽  
Núria Cuadrado ◽  
Jessica Calvo ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Twip Steel ◽  
Low Cycle Fatigue ◽  
Load Ratio ◽  
Fatigue Behaviour ◽  
Cycle Fatigue ◽  
High Manganese ◽  
Amplitude Control ◽  
Cut Edge ◽  
Mechanical Cutting

In the last years, car bodies are increasingly made with new advanced high-strength steels, for both lightweighting and safety purposes. Among these new steels, high-manganese or TWIP steels exhibit a promising combination of strength and toughness, arising from the austenitic structure, strengthened by C, and from the twinning induced plasticity effect. Mechanical cutting such as punching or shearing is widely used for the manufacturing of car body components. This method is known to bring about a very clear plastic deformation and therefore causes a significant increase of mechanical stress and micro-hardness in the zone adjacent to the cut edge. To improve the cut edge quality, surface treatments, such as sandblasting, are often used. This surface treatment generates a compressive residual stress layer in the subsurface region. The monotonic tensile properties and deformation mechanisms of these steels have been extensively studied, as well as the effect of grain size and distribution and chemical composition on fatigue behaviour; however, there is not so much documentation about the fatigue performance of these steels cut using different strategies. Thus, the aim of this work is to analyse the fatigue behaviour of a TWIP steel after mechanical cutting with and without sandblasting in Low and High-Cycle Fatigue regimes. The fatigue behaviour has been determined at room temperature with tensile samples tested with a load ratio of 0.1 and load amplitude control to analyse High-Cycle Fatigue behaviour; and a load ratio of -1 and strain amplitude control to determine the Low-Cycle Fatigue behaviour. Samples were cut by shearing with a clearance value of 5%. Afterwards, a part of the cut specimens were manually blasted using glass microspheres of 40 to 95 microns of diameter as abrasive media. The results show a beneficial effect of the sandblasting process in fatigue behaviour in both regimes, load amplitude control (HCF) and strain amplitude control (LCF) tests, when these magnitudes are low, while no significant differences are observed with higher amplitudes. low-cycle fatigue, high-cycle fatigue, mechanical cutting, sandblasting, high manganese steel, TWIP steel

scholarly journals Fatigue behaviour of open-hole samples and automotive mini-structures made of woven glass-fibre-reinforced polyamide 6,6

2018 ◽  
Vol 165 ◽  
pp. 07007
Author(s):  
Amélie Malpot ◽  
Fabienne Touchard ◽  
Sébastien Bergamo ◽  
Catherine Peyrac ◽  
Richard Montaudon ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Thermoplastic Composite ◽  
Semiempirical Model ◽  
Open Hole ◽  
Automotive Parts ◽  
Glass Fibre Reinforced ◽  
Semi Empirical ◽  
Non Destructive

In the automotive industry, the integration of thermoplastic composite components represents a high-potential solution to the mass reduction challenge. In this study, a woven glassfibre-reinforced composite with a polyamide 6,6 matrix is considered for the purpose of being integrated into automotive parts. Tension-tension fatigue tests were conducted on [(0/90)3] openhole samples. These tests were instrumented with non-destructive techniques, namely acoustic emission and infrared thermography. Acoustic emission results showed fibre-matrix debonding and fibre breakages in open-hole samples, located around the hole. Furthermore, 3-point bending fatigue tests were performed on “omega” mini-structures. A semi-empirical model was used in order to predict the fatigue lives of both open-hole coupons and automotive mini-structures. Predictions of the model for open-holes samples underestimate experimental fatigue lives. Nevertheless, the semiempirical model showed good results for the fatigue life prediction of composite mini-structures.

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