Discrete Damage Modelling of Delamination Migration in Clamped Tapered Laminated Beam Specimens

Adluru, Hari K.; Hoos, Kevin H.; Iarve, Endel V.

doi:10.12783/asc2017/15240

Cited by 7 publications

(10 citation statements)

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“…Understanding the implications of input property variation and scaling is also critical to application of progressive damage analysis (PDA) to design and certification of composite structures. Thus recently performed simulations of failure initiation and propagation in Clamped Tapered Beam (CTB) specimens [2] showed good agreement with experimental data for ply level transverse strength parameter obtained by using 3 point bend (3PB) test method [3] whereas the results obtained by using an almost two times lower value resulting from tensile testing of 90° coupons [4] resulted in 30% underprediction of the peak load. The goal of the present work is to introduce spatial scatter of transverse strength parameters into simulations and attempt to predict the strength of all categories of coupons.…”

Section: Introductionmentioning

confidence: 64%

Discrete Damage Modeling of Matrix Dominated Failure Including Random Spatial Variation of Strength

Hoos¹,

Iarve²

2018

American Society for Composites 2018

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Discrete Damage Modeling (DDM) was applied to strength prediction of three types of composite tape specimens exhibiting rather brittle behavior. These were transverse tensile coupons, three-point bend 90° coupons and NASA LaRC Clamped Tapered Beam sub-element. The performed strength predictions are sensitive to the value of the transverse tensile strength Y t. Deterministic strength predictions required different values of Y t for realistic prediction of strength for the three specimen categories. Weibull scaled seeding of transverse tensile strength was introduced to address this problem. Cohesive Zone Method (CZM) in the field of random initiation strength distribution was examined and revealed that a finite seed length is required in order the reproduce brittle behavior. A 0.4mm seed length window was applied and resulted in realistic predictions of strength in all three specimens based on the Y t =64MPa measured on standard ASTM 90° coupons and Weibull modulus of α=13.

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Section: Introductionmentioning

confidence: 64%

Discrete Damage Modeling of Matrix Dominated Failure Including Random Spatial Variation of Strength

Hoos¹,

Iarve²

2018

American Society for Composites 2018

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“…The main difference was that the initial matrix crack location was predicted near interface 2, at the weak singularity in the taper region, whereas in the experiments it was observed within the taper region between interface 1 and 2. Differences between "as manufactured" vs "as designed" geometry near the taper [7], and potential residual thermal stress effect have been considered as main causes for this discrepancy [23]. In addition, the simulations also predicted multiple migration attempts (vertical red lines) prior to the final migration.…”

Section: B Quasi-staticmentioning

confidence: 99%

Correction: Simulating the Clamped Tapered Beam Specimen under Quasi-Static and Fatigue Loading using Floating Node Method

Seshadri

Carvalho

Ratcliffe

et al. 2018

2018 AIAA/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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As part of the NASA Advanced Composites Project (ACP), a sub-element has been designed to provide validation data for progressive damage analysis models. The clamped tapered beam is a cross-ply laminated composite specimen designed to validate the simulation of the onset of matrix cracks and their interaction with delaminations, including delamination migration. A tapered geometry was used to localize the first damage occurrence in the tapered region, without prescribing an initial crack. The boundary and loading conditions were chosen to favor delamination growth and subsequent migration after the first damage occurrence. The typical sequence of events consists of a matrix crack located at the tapered region, leading to delamination onset, followed by delamination growth and subsequent delamination migration to a different interface via a dominant matrix crack. The Clamped Tapered Beam (CTB) was tested in both quasi-static and fatigue regimes. The results obtained are used in this study to assess and validate a methodology based on the Floating Node Method (FNM) implemented as an Extended Interface Element. In this methodology, quasi-static and fatigue damage formation and development are modeled by combining FNM to represent crack networks, with Directional Cohesive Zone Elements (DCZE) and Virtual Crack Closure Technique (VCCT), respectively. Qualitatively, the methodology is capable of predicting the sequence of events and overall failure morphology. Quantitatively, the simulation results generally bound the experimental data, based on the range of the characterization data used. In this paper, the results from quasi static and fatigue simulations are compared and correlated with experimental data.

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“…The main difference in CTB is the tapered edge of the short arm and the absence of initial delamination, thus allowing one to study not only the delamination migration phenomena but also the failure initiation from pristine tapered edges. Static loading of the CTB was previously considered in [2] and the present manuscript will focus on fatigue monotonic fatigue loading.…”

Section: Inroductionmentioning

confidence: 99%

“…A discussion of CBT including static analysis was performed in Ref [2]. CTB schematics, dimensions, boundary conditions and load application points are shown in Figure 1.…”

Section: Clamped Tapered Beam Specimen (Ctb)mentioning

confidence: 99%

“…These element sizes correspond to approximately 1, ½ and ¼ of the ply thickness. From the mesh convergence studies under static loading [2], it was concluded the fine model (mesh size approximately ½ ply thickness) is appropriate considering both accuracy and computational time. Hence, the results reported are obtained by using fine (½ ply) model.…”

Section: Clamped Tapered Beam Specimen (Ctb)mentioning

confidence: 99%

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Discrete Damage Modelling of Clamped Tapered Beam Specimen Under Fatigue Loading

Adluru¹,

Iarve²,

Hoos³

2018

American Society for Composites 2018

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Clamped Tapered Beam (CTB) sub-element, proposed by Advanced Composite Project Team at the NASA Langley Research Center was studied under monotonic fatigue loading. The specimen was designed to study matrix crack initiation from pristine condition, delamination initiation and propagation including migration from one interface to other. Regularized eXtended Finite Element Method (Rx-FEM), which allows modeling displacement discontinuities associated with matrix cracks independent of the mesh orientation was used for analysis. Previously developed fatigue Cohesive Zone Method (CZM) was modified to include the S-N information in the Newton-Rapson equilibrium loop. The analysis was conducted in two phases, before and after the experimental data was revealed. The blind predictions were conducted at R=0.1 load ratio for 80% and 70% values of the fatigue load amplitude with respect to static strength and overestimated the rate of delamination growth. The corrected predictions took into account the R=0.2 load ratio, thermal residual stresses and were based on the modified algorithm. The failure event sequence and the respective cycle counts were consistent with experimental data.

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Discrete Damage Modelling of Delamination Migration in Clamped Tapered Laminated Beam Specimens

Cited by 7 publications

References 0 publications

Discrete Damage Modeling of Matrix Dominated Failure Including Random Spatial Variation of Strength

Discrete Damage Modeling of Matrix Dominated Failure Including Random Spatial Variation of Strength

Correction: Simulating the Clamped Tapered Beam Specimen under Quasi-Static and Fatigue Loading using Floating Node Method

Discrete Damage Modelling of Clamped Tapered Beam Specimen Under Fatigue Loading

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