Experimental and numerical study on the tensile failure behavior of toughened-interlayer composite laminates with automated fiber placement (AFP) induced gap and overlap defects

Nguyen, Minh Hoang; Davidson, Paul; Waas, Anthony M.

doi:10.1007/s12289-020-01581-w

Cited by 16 publications

(9 citation statements)

References 35 publications

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“…In addition, manufacturing‐induced defects can become critical under service conditions. The types, distribution, and amount of defects alone are insufficient to predict the possible reduction of mechanical performance, 18 and their effects on service conditions need to be examined. Hydrothermal aging by hot‐water absorption induces different physical or chemical effects on the composites, such as (i) plasticization or antiplasticization of the matrix, (ii) swelling and induced internal stresses, cracking/crazing due to osmosis, and (iii) damage of the fiber/matrix interface due to water presence 19–21 .…”

Section: Introductionmentioning

confidence: 99%

An experimental implication of long‐term hot‐wet‐aged carbon fiber/polyether ketone ketone composites: The impact of automated fiber placement process parameters and process‐induced defects

Şükür

Elmas

Eskizeybek

et al. 2023

J of Applied Polymer Sci

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During the service life of aerospace‐grade composites, process parameters and process‐induced defects may become crucial. Most studies in this field have mainly focused on the relationship between process‐induced defects and mechanical performance. However, the potential impact of process parameters and process‐induced defects on the service life of composites serving under severe service conditions has received little attention. In this work, the effects of hydrothermal conditioning on the mechanical performance of carbon fiber/polyether ketone ketone (CF/PEKK) composites are examined, along with the correlation between automated fiber placement (AFP) process parameters and process‐induced defects. For this, gap and overlap defects integrated CF/PEKK laminates were exposed to a long‐term (90 days) hot‐wet aging environment to simulate the actual service conditions. Defect‐induced composite samples reached saturation point at the end of 30 days with a mass gain of 0.2 wt%. The aging process resulted in an increase in the degree of crystallization by almost 14% without a change in the chemical structure, indicating the postcrystallization of the PEKK matrix. Even though the thermo‐mechanical performance diminished (~25%) with the aging process, storage modulus was slightly affected by process parameters and process‐induced defects. Considering the flexural and shear test results after the aging process, the impact of gap and overlap defects on the service life of AFP composites can be minimized with higher compaction forces (600 N) and lower lay‐up speeds (0.1 m/s).

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Section: Introductionmentioning

confidence: 99%

An experimental implication of long‐term hot‐wet‐aged carbon fiber/polyether ketone ketone composites: The impact of automated fiber placement process parameters and process‐induced defects

Şükür

Elmas

Eskizeybek

et al. 2023

J of Applied Polymer Sci

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“…In addition to the experimental studies described above, other studies have been presented in the last years that have focused on the modeling and simulation of AFP induced defects. 19–21…”

Section: Introductionmentioning

confidence: 99%

“…18 In addition to the experimental studies described above, other studies have been presented in the last years that have focused on the modeling and simulation of AFP induced defects. [19][20][21] The general conclusion that can be drawn from literature is that the mechanical knockdown of an AFP laminate results mainly from the induced fiber waviness. The amount of defects by itself is therefore not sufficient to anticipate the possible reduction of mechanical performance.…”

Section: Introductionmentioning

confidence: 99%

Effects of defects in automated fiber placement laminates and its correlation to automated optical inspection results

Böckl

Wedel

Misik

et al. 2022

Journal of Reinforced Plastics and Composites

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Automated Fiber Placement (AFP) is a widely used production process for the manufacturing of large scale CFRP parts. However, the occurrence of manufacturing defects such as gaps or overlaps is still a common problem in today’s AFP production environments. This study investigates the effect of different defect configurations on the mechanical performance (i.e., tensile strength, flexural strength, and shear strength) of AFP laminates. The results are then linked to the data generated “inline” by a ply inspection system. We use the Pearson correlation in order to relate the measured defect volume to the strength of samples containing different types of defects. A clear knockdown in tensile strength was found for specimens with gaps or overlaps that caused a high amount of fiber undulations in the laminate. The sensor data analysis showed a similar trend. Specimens with a high defect volume had significantly lower values for the tensile strength. A correlation coefficient of −0.98 between these two values was calculated. The obtained results are a promising step towards automated quality inspection for the AFP process.

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“…[5][6][7] However, the level of inhomogeneity and also misalignment is a function of many parameters, such as the dimension of the gaps, stacking sequence, ply staggering, and structure's curvature. 8,9 The size of the gap may vary by the width of the single fiber tow, geometry, and complexity of the composite structures, material systems, and curing process. Although the maximum width of the gap can be assumed as the width of a single fiber tow, the allowable width of this defect should not exceed 3.0 mm in practical applications.…”

Section: Introductionmentioning

confidence: 99%

“…In conjunction with Continuum progressive damage model, a FE model was developed in Ref. 8 accounting for the effect of gap and overlap on the tensile and compressive strengths of composite laminates.…”

Section: Introductionmentioning

confidence: 99%

Induced defect layer method to characterize the effect of fiber tow gaps for the laminates manufactured by automated fiber placement technique

Ghayour

Hojjati

Ganesan

2021

Journal of Composite Materials

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Automated manufacturing defects are new types of composite structure defects induced during fiber deposition by robots. Fiber tow gap is one of the most probable types of defects observed in the Automated Fiber Placement (AFP) technique. This defect can affect the structural integrity of structures by reducing structural strength and stiffness. The effect of this defect on the mechanical response of the composite laminates has been investigated experimentally in the literature. However, there is still no efficient numerical/analytical method for damage assessment of composite structures with distributed induced gaps manufactured by the AFP technique. The present paper aims to develop the Induced Defect Layer Method (IDLM), a new robust meso-macro model for damage analysis of the composite laminates with gaps. In this method, a geometrical parameter, Gap Percentage (GP), is implemented to incorporate the effect of induced-gaps in the elastic, inelastic, and softening behavior at the material points. Thus, while the plasticity and failure of the resin pockets in conjunction with intralaminar composite damages can be evaluated by this method, the defective areas are not required to be defined as resin elements in the Finite Element (FE) models. It can also be applied for any arbitrary distributions of the defects in the multi-layer composite structures, making it a powerful tool for continuum damage analysis of large composite structures. Results indicate that the proposed method can consider the effect of gaps in both elastic and inelastic behavior of the composite laminate with defects. It also provides good agreement with the experimental results.

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Experimental and numerical study on the tensile failure behavior of toughened-interlayer composite laminates with automated fiber placement (AFP) induced gap and overlap defects

Cited by 16 publications

References 35 publications

An experimental implication of long‐term hot‐wet‐aged carbon fiber/polyether ketone ketone composites: The impact of automated fiber placement process parameters and process‐induced defects

An experimental implication of long‐term hot‐wet‐aged carbon fiber/polyether ketone ketone composites: The impact of automated fiber placement process parameters and process‐induced defects

Effects of defects in automated fiber placement laminates and its correlation to automated optical inspection results

Induced defect layer method to characterize the effect of fiber tow gaps for the laminates manufactured by automated fiber placement technique

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