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ASTM D6671 · Mixed-mode fracture envelope

Measures delamination toughness when opening and sliding act together at different mode mixtures.

Analytical / measured-data assessment

Official ASTM D6671/D6671M-22 ↗

Open this exercise in Workbench ↗

CDS sign-in and suitable licensed access may be required.

Recorded instructional case · Workbench captures and saved calculation data, October 2026. This website preview does not run the test.

01

Mixed-mode setup view

Actual Workbench D6671 mixed-mode fracture envelope setup
Recorded Workbench setup or assessment view · Full-size capture ↗
02

Calculated assessment

Calibrated BK envelope

Critical energy (N/mm)

Recorded instructional case. GII / (GI + GII) versus Critical energy (N/mm). Exact saved values are available in the table below.0.900.6750.250.450.50.2250.7501

GII / (GI + GII)

View plotted values
Calibrated BK envelope — recorded values
SeriesGII / (GI + GII)Critical energy (N/mm)
Calibrated BK envelope00.3
Calibrated BK envelope0.010.3003785744066881
Calibrated BK envelope0.020.301147622999748
Calibrated BK envelope0.030.3021955597370405
Calibrated BK envelope0.040.30347894238565293
Calibrated BK envelope0.050.30497168102600997
Calibrated BK envelope0.060.30665569253239094
Calibrated BK envelope0.070.3085174210054149
Calibrated BK envelope0.080.31054618121573874
Calibrated BK envelope0.090.3127332499866653
Calibrated BK envelope0.10.31507131858905746
Calibrated BK envelope0.110.3175541395538483
Calibrated BK envelope0.120.320176286865889
Calibrated BK envelope0.130.3229329864303604
Calibrated BK envelope0.140.325819992243702
Calibrated BK envelope0.150.32883349347783125
Calibrated BK envelope0.160.3319700431642319
Calibrated BK envelope0.170.3352265023902792
Calibrated BK envelope0.180.33859999590061374
Calibrated BK envelope0.190.3420878762561167
Calibrated BK envelope0.20.3456876945291811
Calibrated BK envelope0.210.3493971760703781
Calibrated BK envelope0.220.3532142002652066
Calibrated BK envelope0.230.3571367834696158
Calibrated BK envelope0.240.3611630645065882
Calibrated BK envelope0.250.3652912922472093
Calibrated BK envelope0.260.3695198149041109
Calibrated BK envelope0.270.37384707074354684
Calibrated BK envelope0.280.37827157998189825
Calibrated BK envelope0.290.3827919376781539
Calibrated BK envelope0.30.3874068074694367
Calibrated BK envelope0.310.3921149160245004
Calibrated BK envelope0.320.39691504811215766
Calibrated BK envelope0.330.40180604219917804
Calibrated BK envelope0.340.4067867865063285
Calibrated BK envelope0.350.4118562154626746
Calibrated BK envelope0.360.4170133065075875
Calibrated BK envelope0.370.42225707719756284
Calibrated BK envelope0.380.42758658258127136
Calibrated BK envelope0.390.43300091281150954
Calibrated BK envelope0.40.4384991909670925
Calibrated BK envelope0.410.4440805710614037
Calibrated BK envelope0.420.44974423621740633
Calibrated BK envelope0.430.45548939699154023
Calibrated BK envelope0.440.46131528983115144
Calibrated BK envelope0.450.4672211756520014
Calibrated BK envelope0.460.4732063385240284
Calibrated BK envelope0.470.47927008445493197
Calibrated BK envelope0.480.4854117402623598
Calibrated BK envelope0.490.4916306525265176
Calibrated BK envelope0.50.49792618661593413
Calibrated BK envelope0.510.5042977257799005
Calibrated BK envelope0.520.5107446703017947
Calibrated BK envelope0.530.5172664367081078
Calibrated BK envelope0.540.5238624570285186
Calibrated BK envelope0.550.5305321781028326
Calibrated BK envelope0.560.5372750609310137
Calibrated BK envelope0.570.5440905800629039
Calibrated BK envelope0.580.5509782230245487
Calibrated BK envelope0.590.5579374897783371
Calibrated BK envelope0.60.56496789221442
Calibrated BK envelope0.610.572068953671101
Calibrated BK envelope0.620.5792402084820988
Calibrated BK envelope0.630.5864812015487639
Calibrated BK envelope0.640.5937914879354994
Calibrated BK envelope0.650.6011706324867796
Calibrated BK envelope0.660.6086182094643016
Calibrated BK envelope0.670.6161338022029159
Calibrated BK envelope0.680.6237170027841024
Calibrated BK envelope0.690.6313674117258458
Calibrated BK envelope0.70.6390846376878648
Calibrated BK envelope0.710.6468682971912216
Calibrated BK envelope0.720.6547180143514186
Calibrated BK envelope0.730.6626334206241549
Calibrated BK envelope0.740.6706141545629732
Calibrated BK envelope0.750.6786598615880923
Calibrated BK envelope0.760.68677019376576
Calibrated BK envelope0.770.6949448095975199
Calibrated BK envelope0.780.7031833738188202
Calibrated BK envelope0.790.7114855572064371
Calibrated BK envelope0.80.7198510363942189
Calibrated BK envelope0.810.7282794936966914
Calibrated BK envelope0.820.7367706169400965
Calibrated BK envelope0.830.7453240993004637
Calibrated BK envelope0.840.7539396391483384
Calibrated BK envelope0.850.7626169398998199
Calibrated BK envelope0.860.7713557098735793
Calibrated BK envelope0.870.7801556621535501
Calibrated BK envelope0.880.7890165144570053
Calibrated BK envelope0.890.7979379890077485
Calibrated BK envelope0.90.8069198124141677
Calibrated BK envelope0.910.8159617155519097
Calibrated BK envelope0.920.8250634334509561
Calibrated BK envelope0.930.8342247051868841
Calibrated BK envelope0.940.8434452737761173
Calibrated BK envelope0.950.8527248860749781
Calibrated BK envelope0.960.8620632926823635
Calibrated BK envelope0.970.8714602478458806
Calibrated BK envelope0.980.8809155093712808
Calibrated BK envelope0.990.890428838535049
Calibrated BK envelope10.9000000000000001
03

Set up in CDS

  1. Enter calibrated GIc, GIIc and the BK exponent.
  2. Supply GI and GII from a compatible test or analysis.
  3. Evaluate the mode fraction and mixed-mode envelope.
  4. Compare total energy with the calibrated critical value.
Native mixed-mode fixture viewBenzeggagh–Kenane energy envelopeIndependent Mode I and Mode II energy inputs
Inputs for this recorded case
  • 150 × 25 × 2 mm
  • 16 plies / 2 mm
  • Selected force 0 N
  • Explicit source calibration/properties

These are teaching-case inputs, not ASTM-prescribed specimen dimensions or acceptance criteria.

04

Readout & interpretation

Mode II fraction
0.6667 —
Mixed-mode critical energy
0.6136 N/mm
Applied total energy
0.3 N/mm
Demand / critical energy
0.4889 —

Calibrated fracture envelope. Lever-fixture mechanics and crack propagation are excluded.

About this ASTM reference

Standard Test Method for Mixed Mode I-Mode II Interlaminar Fracture Toughness of Unidirectional Fiber Reinforced Polymer Matrix Composites

Active catalog edition checked October 10, 2026. The official standard defines the physical method; the CDS example below has a narrower modeling scope. Full procedures remain on ASTM’s site.

Find this setup in Workbench

Opens the connected guided study. Select the matching ASTM setup in the Test menu to inspect its fixture.

What this CDS case represents

Read the actual ASTM standard ↗

Calibrated fracture envelope. Lever-fixture mechanics and crack propagation are excluded.

This analytical or measured-data model provides its own curves and metrics. Synchronized failure playback is not supported; a mounted fixture view does not imply that contact, crack growth or impact history is solved.

Model basis · equation and interpretation

Gc = GIc + (GIIc − GIc) [GII/(GI + GII)]^η.

GIc and GIIc are measured pure-mode toughnesses, η a calibrated BK exponent, and GI/GII independently supplied energy-release rates. No MMB lever geometry is solved. The laminate link retains provenance but does not infer the supplied energies from its stiffness.

Instructional model comparison, not experimental validation or ASTM certification. Physical testing requires the licensed standard and a qualified test program.