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

Stock, Johannes; Kerschreiter, Johanna

doi:10.4028/www.scientific.net/amr.1140.288

Cited by 5 publications

(10 citation statements)

References 7 publications

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“…The reason is the redistribution of mechanical shear stresses because of the thermal degradation of the CFRP at the cutting edge. These lead to a reduction of the notch stress concentrations [6] [7]. However, this trend is reversed with a further growth of the MEZ, as the present results indicate.…”

Section: Quasistatic and Cyclic Tensile Testing Of Milled And Remote-supporting

confidence: 58%

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Mechanical Properties of Remote-Laser Cut CFRP and Thermographic Laser-Process Monitoring

Rose¹,

Schettler²,

Klemm³

et al. 2020

MSA

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Remote-laser beam cutting is a productive technology without tool wear. Especially when cutting carbon fiber reinforced polymers (CFRP), it offers constant manufacturing quality. Since it is a thermal process, a heat-affected zone (HAZ) is formed at the edge of the cut. Based on quasi-static and cyclic mechanical tests on open-hole specimens, the influence of the process on the mechanical properties of CFRP is shown. The quasi-static tests are in good correlation with results from other researchers by indicating an increase in the maximum tensile stress of the test specimens, cut by remote-laser. The reason is the rearrangement of the shear stresses and a reduction of the notch stress concentration. However, the results of the present study show that excessive expansion of the HAZ leads to a reduction in the maximum tensile stress compared to milled test specimens. Under cyclic load conditions, remote-laser beam cutting does not lead to a more pronounced degradation than milling. The mechanical properties of the notched test pieces are sensitive to the expansion of the HAZ. For the production of components it is therefore necessary that the remote-laser beam cutting is carried out under controlled and documentable conditions. For this purpose, process thermography was tested as a tool for quality assurance. The results show that the technology is basically suitable for this task.

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Section: Quasistatic and Cyclic Tensile Testing Of Milled And Remote-supporting

confidence: 58%

“…The reason is the local redistribution of shear stresses due to the evaporation of the matrix at the cut edge. This results in a reduction of the notch stress concentration of the tensile stresses in the fibers aligned in the direction of loading [6] [7].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Remote-Laser Cut CFRP and Thermographic Laser-Process Monitoring

Rose¹,

Schettler²,

Klemm³

et al. 2020

MSA

View full text Add to dashboard Cite

show abstract

“…The reason for this can be found in two opposing effects of the thermal damage; on the one hand side the damage reduces the material strength and so supports a sooner failure of the structure, on the other hand side damage leads to a stiffness-reduction as well, which diminishes the notch effect. Similar effects were described in [3], where similar open hole specimens were tested.…”

Section: Open Hole Testmentioning

confidence: 62%

“…In different publications, for example [3], [4] or [5], a diverging behaviour of HAZ in CFRP was described, here further experiments and simulations are required. In comparative tensile tests different machining technologies for CFRP were compared in experiments and simulations and gave a validation for the material model.…”

Section: Resultsmentioning

confidence: 99%

Numerical analysis of the thermally induced damage in remote laser cut carbon fibre reinforced polymers

Schmidt

Rose

Zimmermann

et al. 2019

Proc Appl Math and Mech

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Remote laser cutting in carbon fibre reinforce polymers is a promising machining technology which can reduce the main drawback in laser cutting, the heat affected zone. This contribution presents a two-step modelling approach for the simulation of remote laser cut carbon fibre reinforce polymers, consisting of a damage model for the initially intact material and a model for the thermally damaged material. The static damage behaviour was modelled with the Pinho material model [1], which stands out due to its physically based failure criteria. Initial thermal damages caused by the heat input were modelled with the damage parameters of the Pinho model. The dimensions of the heat affected zone are taken from polished micro sections of the material around the cutting edge. As a numerical example, comparative tensile tests of milled and laser cut open hole specimens were simulated. The advantage of these specimens is the notch effect around the holes in the heat affected zone, which amplifies the differences between the two cutting technologies.

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“…Laser cutting, as a fast, versatile and wear-free cutting technology has the drawback of a heat affected zone (HAZ), an area where the matrix is evaporated or chemically decomposed. As [1] and [2] stated, the HAZ strongly affects the mechanical properties of CFRP and thus needs to be considered in the structural analysis. Possible ways to identify the HAZ dimensions are 1D heat conduction calculations as presented in [3] or the identification from micro-sections of the cutting gap [4].…”

Section: Introductionmentioning

confidence: 99%

Analysis of the remote laser cutting process induced damage in carbon fibre reinforced polymers with cutting process simulations

Schmidt

Rose

Zimmermann

et al. 2021

Proc Appl Math and Mech

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Remote laser cutting in carbon fibre reinforced polymers is a promising machining technology, which can reduce the main drawback in laser cutting, the heat affected zone. As the heat affected zone has a strong influence on the mechanical behaviour of the composite, an exact characterisation is a key challenge for the simulation and design of fibre reinforced polymers. In order to reach this goal, a laser cutting process model is introduced. Based on the finite difference method, the heat transport is modelled on a macroscopic scale. The macroscopic material parameters are calculated with a rule of mixture. Matrix and fibre evaporation, which cause the formation of the matrix evaporation zone and the gap, are modelled with phase transitions and an adaption in the rule of mixture. The simulation results are validated with micro-sections of the cutting gap.

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

Cited by 5 publications

References 7 publications

Mechanical Properties of Remote-Laser Cut CFRP and Thermographic Laser-Process Monitoring

Mechanical Properties of Remote-Laser Cut CFRP and Thermographic Laser-Process Monitoring

Numerical analysis of the thermally induced damage in remote laser cut carbon fibre reinforced polymers

Analysis of the remote laser cutting process induced damage in carbon fibre reinforced polymers with cutting process simulations

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