spore: profile
id: aluminium-honeycomb-hexweb
spore_version: 0.2
family: aluminium-honeycomb
name: "Aluminium honeycomb core (Hexcel HexWeb CR III, 5052 and 5056)"
abbreviation: "Al honeycomb"
role: structural core
category: composites
type: honeycomb-sandwich
summary: >
  Aluminium honeycomb core is a lightweight core for sandwich panels, in which two thin facings are bonded to a
  hexagonal-cell core that holds them apart. Hexcel's HexWeb CR III core is made from 5052 or 5056 aluminium-magnesium
  foil in the H39 temper and carries a corrosion-resistant coating. For 5052 in a 3/16 in cell at a nominal 3.1 pcf,
  Hexcel gives a typical stabilized compressive strength of 335 psi and a minimum of 215 psi. NASA Glenn reports that the
  5052 core is commonly used as the core of composite sandwich panels for lightweight structures.
best_for: "Stiff, light sandwich panels for aerospace structures that need a corrosion-resistant aluminium core (HexWeb CR III in 5052 or 5056)"
weakest_at: "Core crush and shear strength (130 psi typical crush strength for 5052 at 3.1 pcf) and a temper that is often not stated on orders"
identity:
  formula: "Expanded aluminium-magnesium alloy foil core: 5052 (Mg 2.2 to 2.8 wt%, Cr 0.15 to 0.35 wt%) or 5056 (Mg 4.50 / 5.6 wt%), with a CR III coating of a chromate-based layer and an organo-metallic polymer"
  source: nasa-tm-2018
  where: "5052 chemistry: AMS4004D column of Table I (p. 2); 5056 chemistry: composition table of the aircraftmaterials 5056 page; CR III coating: Corrosion-Resistant Coatings section of the Hexcel guide (p. 8)"
  designations:
    - {system: UNS, code: A95052, source: aircraftmaterials-5052, where: "Alloy 5052 page, UNS A95052 entry (listed under 5052-0 and 5052-H32)"}
    - {system: AMS, code: AMS4004D, note: "aluminium foil 2.5Mg-0.25Cr (5052-H191), chemistry specification", source: nasa-tm-2018, where: "Table I column heading and reference 3; NASA states the core chemistry matches this specification"}
    - {system: Trade name, code: "HexWeb® CR III", note: "corrosion-resistant aluminium honeycomb in 5052 and 5056", source: hexcel-cr3-ds, where: "Title and Type Designation, p. 1"}
tags:
  environments: []
  stresses: [extreme-heat]
  applications: [structures]
properties:
  - benchmark: density
    label: "Nominal core density, CR III 3/16 in cell, 5052"
    value: 3.1
    unit: pcf
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", designation: "CR-III, 3/16, 5052, 3.1N (cell walls not perforated)", tolerance: "plus or minus 10 percent from nominal, per the Hexcel guide"}
    method: "Nominal density printed in the Hexcel product data sheet; the Hexcel guide states aerospace-grade core stays within 10 percent of list nominal"
    status: ground
    source: hexcel-cr3-ds
    where: "Type Designation, p. 1 (example CR-III, 3/16, 5052, 3.1N); Table I, nominal density column"
  - benchmark: bare_compressive_strength
    label: "Bare compressive strength, typical, 5052 core"
    value: 290
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "typical (typ)", loading: "T direction, no facings bonded", test_thickness: "0.625 in (table note)"}
    method: "Typical value printed in Table I of the Hexcel data sheet; the Hexcel guide defines bare compressive strength as the ultimate compressive strength of the core without facings"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Bare Strength typ"
  - benchmark: bare_compressive_strength
    label: "Bare compressive strength, minimum average, 5052 core"
    value: 200
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "minimum average (min)", loading: "T direction, no facings bonded", test_thickness: "0.625 in (table note)"}
    method: "Minimum average printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Bare Strength min"
  - benchmark: stabilized_compressive_strength
    label: "Stabilized (flatwise) compressive strength, typical, 5052 core"
    value: 335
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "typical (typ)", facings: "0.032 in 5052 facings bonded to each side (Hexcel guide test method)", test_thickness: "0.625 in (table note)"}
    method: "Typical value printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Stabilized Strength typ"
  - benchmark: stabilized_compressive_strength
    label: "Stabilized (flatwise) compressive strength, minimum average, 5052 core"
    value: 215
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "minimum average (min)", facings: "0.032 in 5052 facings bonded to each side (Hexcel guide test method)"}
    method: "Minimum average printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Stabilized Strength min"
  - benchmark: stabilized_compressive_modulus
    label: "Stabilized compressive modulus, typical, 5052 core"
    value: 75
    unit: ksi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "typical (typ)"}
    method: "Typical value printed in Table I of the Hexcel data sheet, from the initial straight-line slope of the stress-strain curve (Hexcel guide definition)"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Modulus typ"
  - benchmark: crush_strength
    label: "Crush strength, typical, 5052 core"
    value: 130
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "typical (typ)", basis: "average crush load per unit cross-sectional area after the ultimate compressive strength is exceeded (Hexcel guide)"}
    method: "Typical value printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Crush Strength typ"
  - benchmark: plate_shear_strength_l
    label: "Plate shear strength in the L (ribbon) direction, typical, 5052 core"
    value: 210
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "L (ribbon) direction", statistic: "typical (typ)", test_thickness: "0.625 in (table note)"}
    method: "Typical value printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Plate Shear L Direction Strength typ"
  - benchmark: plate_shear_strength_l
    label: "Plate shear strength in the L (ribbon) direction, minimum average, 5052 core"
    value: 155
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "L (ribbon) direction", statistic: "minimum average (min)"}
    method: "Minimum average printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Plate Shear L Direction Strength min"
  - benchmark: plate_shear_modulus_l
    label: "Plate shear modulus in the L (ribbon) direction, typical, 5052 core"
    value: 45.0
    unit: ksi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "L (ribbon) direction", statistic: "typical (typ)"}
    method: "Typical value printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Plate Shear L Direction Modulus typ"
  - benchmark: plate_shear_strength_w
    label: "Plate shear strength in the W (transverse) direction, typical, 5052 core"
    value: 125
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "W (transverse) direction", statistic: "typical (typ)"}
    method: "Typical value printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Plate Shear W Direction Strength typ"
  - benchmark: plate_shear_strength_w
    label: "Plate shear strength in the W (transverse) direction, minimum average, 5052 core"
    value: 90
    unit: psi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "W (transverse) direction", statistic: "minimum average (min)"}
    method: "Minimum average printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Plate Shear W Direction Strength min"
  - benchmark: plate_shear_modulus_w
    label: "Plate shear modulus in the W (transverse) direction, typical, 5052 core"
    value: 22.0
    unit: ksi
    scope: material
    conditions: {alloy: "5052, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "W (transverse) direction", statistic: "typical (typ)"}
    method: "Typical value printed in Table I of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table I (p. 4), 5052 row 3/16 cell, 3.1 pcf, Plate Shear W Direction Modulus typ"
  - benchmark: bare_compressive_strength
    label: "Bare compressive strength, typical, 5056 core"
    value: 380
    unit: psi
    scope: material
    conditions: {alloy: "5056, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "typical (typ)", loading: "T direction, no facings bonded", test_thickness: "0.625 in (table note)"}
    method: "Typical value printed in Table II of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table II (p. 5), 5056 row 3/16 cell, 3.1 pcf, Bare Strength typ"
  - benchmark: stabilized_compressive_strength
    label: "Stabilized (flatwise) compressive strength, typical, 5056 core"
    value: 410
    unit: psi
    scope: material
    conditions: {alloy: "5056, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "typical (typ)", facings: "0.032 in 5052 facings bonded to each side (Hexcel guide test method)"}
    method: "Typical value printed in Table II of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table II (p. 5), 5056 row 3/16 cell, 3.1 pcf, Stabilized Strength typ"
  - benchmark: stabilized_compressive_modulus
    label: "Stabilized compressive modulus, typical, 5056 core"
    value: 97
    unit: ksi
    scope: material
    conditions: {alloy: "5056, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "typical (typ)"}
    method: "Typical value printed in Table II of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table II (p. 5), 5056 row 3/16 cell, 3.1 pcf, Modulus typ"
  - benchmark: crush_strength
    label: "Crush strength, typical, 5056 core"
    value: 170
    unit: psi
    scope: material
    conditions: {alloy: "5056, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", statistic: "typical (typ)"}
    method: "Typical value printed in Table II of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table II (p. 5), 5056 row 3/16 cell, 3.1 pcf, Crush Strength typ"
  - benchmark: plate_shear_strength_l
    label: "Plate shear strength in the L (ribbon) direction, typical, 5056 core"
    value: 265
    unit: psi
    scope: material
    conditions: {alloy: "5056, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "L (ribbon) direction", statistic: "typical (typ)"}
    method: "Typical value printed in Table II of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table II (p. 5), 5056 row 3/16 cell, 3.1 pcf, Plate Shear L Direction Strength typ"
  - benchmark: plate_shear_modulus_l
    label: "Plate shear modulus in the L (ribbon) direction, typical, 5056 core"
    value: 45.0
    unit: ksi
    scope: material
    conditions: {alloy: "5056, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "L (ribbon) direction", statistic: "typical (typ)"}
    method: "Typical value printed in Table II of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table II (p. 5), 5056 row 3/16 cell, 3.1 pcf, Plate Shear L Direction Modulus typ"
  - benchmark: plate_shear_strength_w
    label: "Plate shear strength in the W (transverse) direction, typical, 5056 core"
    value: 150
    unit: psi
    scope: material
    conditions: {alloy: "5056, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "W (transverse) direction", statistic: "typical (typ)"}
    method: "Typical value printed in Table II of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table II (p. 5), 5056 row 3/16 cell, 3.1 pcf, Plate Shear W Direction Strength typ"
  - benchmark: plate_shear_modulus_w
    label: "Plate shear modulus in the W (transverse) direction, typical, 5056 core"
    value: 20.0
    unit: ksi
    scope: material
    conditions: {alloy: "5056, H39 temper", cell_size: "3/16 in", density: "3.1 pcf nominal", direction: "W (transverse) direction", statistic: "typical (typ)"}
    method: "Typical value printed in Table II of the Hexcel data sheet"
    status: ground
    source: hexcel-cr3-ds
    where: "Table II (p. 5), 5056 row 3/16 cell, 3.1 pcf, Plate Shear W Direction Modulus typ"
  - benchmark: cte
    label: "Coefficient of thermal expansion, CR III 5052 and 5056 honeycomb"
    value: 13.2
    unit: "x 10^-6 inch/inch-°F"
    scope: material
    conditions: {alloy: "5052 and 5056", coating: "CR III", form: "hexagonal honeycomb core", temperature_range: "not stated in the source"}
    method: "Value printed in the Hexcel guide physical properties table, as inch/inch per degree F (x 10^-6 as printed)"
    status: ground
    source: hexcel-guide
    where: "Physical properties table, Coefficient of Thermal Expansion row (CR III, CR-PAA, 5052, 5056)"
  - benchmark: elastic_modulus
    label: "Elastic modulus of 5052 H39 honeycomb foil, average"
    value: 8.3
    unit: Msi
    scope: material
    conditions: {alloy: "5052, H39 temper foil", foil_thickness: "0.0016 in", temperature: "room temperature", n: "14 tests in rolling and transverse directions, average reported as 8.3 plus or minus 0.3 Msi"}
    method: "Average of pooled room-temperature foil tensile tests (NASA TM); the report notes datasheets usually cite 10 Msi and its measured values were lower"
    status: ground
    source: nasa-tm-2018
    where: "Section on 5052 H39 foil tensile tests and the aging study (average modulus sentence)"
  - benchmark: elongation
    label: "Strain to failure of 5052 H39 honeycomb foil"
    value: 1.6
    unit: "%"
    scope: material
    conditions: {alloy: "5052, H39 temper foil", foil_thickness: "0.0016 in", temperature: "room temperature", range_reported: "0.5 to 3.4 percent"}
    method: "Average of room-temperature foil tensile tests; the report gives 1.6 percent as the measured average and a range of 0.5 to 3.4 percent"
    status: ground
    note: "Small sample size and foil rather than bulk specimens, as the report itself warns."
    source: nasa-tm-2018
    where: "Section on 5052 H39 foil tensile tests (text after Figure 2)"
  - benchmark: ultimate_tensile_strength
    label: "Ultimate tensile strength, bulk 5052 sheet, H38 (datasheet value)"
    value: 42
    unit: ksi
    scope: material
    conditions: {alloy: "5052 bulk sheet", temper: "H38", basis: "datasheet values as tabulated by NASA, from the datasheets it cites (refs 6 and 7)"}
    method: "Table II of the NASA report, datasheet values for bulk 5052; not a test by the authors"
    status: ground
    source: nasa-tm-2018
    where: "Table II (datasheet values for 5052 bulk material), H38 row"
  - benchmark: yield_strength
    label: "Yield strength, bulk 5052 sheet, H38 (datasheet value)"
    value: 37
    unit: ksi
    scope: material
    conditions: {alloy: "5052 bulk sheet", temper: "H38", basis: "datasheet values as tabulated by NASA, from the datasheets it cites (refs 6 and 7)"}
    method: "Table II of the NASA report, datasheet values for bulk 5052; not a test by the authors"
    status: ground
    source: nasa-tm-2018
    where: "Table II (datasheet values for 5052 bulk material), H38 row, Yield column"
  - benchmark: elongation
    label: "Elongation, bulk 5052 sheet, H38 (datasheet value)"
    value: 7
    unit: "%"
    scope: material
    conditions: {alloy: "5052 bulk sheet", temper: "H38", basis: "datasheet values as tabulated by NASA, from the datasheets it cites (refs 6 and 7)"}
    method: "Table II of the NASA report, datasheet values for bulk 5052; not a test by the authors"
    status: ground
    source: nasa-tm-2018
    where: "Table II (datasheet values for 5052 bulk material), H38 row, Elongation column"
corrosion:
  - environment: "Salt spray and heat ageing (CR III coating on the core)"
    headline: "CR III keeps about 88 percent of its room-temperature shear strength after 350 °F heat ageing and 30-day salt spray."
    effect: "Hexcel reports that shear strength retention after 350 °F heat ageing for up to 500 hours and 30-day salt spray exposure is approximately 88 percent of room-temperature properties with no salt spray exposure, and that weight loss is considerably less than the maximum permitted by MIL-C7438."
    rating: low
    conditions: {coating: "HexWeb CR III", heat_ageing: "350 °F for up to 500 hours", salt_spray: "30 days", reference: "room-temperature properties with no salt spray exposure"}
    source: hexcel-cr3-ds
    where: "Mechanical Properties, p. 3"
  - environment: "Hot, wet or salt environments (alternative coating, CR-PAA)"
    headline: "Hexcel says CR-PAA is better than CR III for bond strength, salt spray, crack growth and hot, wet service."
    effect: "The Hexcel guide describes CR-PAA, a phosphoric acid anodized coating, as superior to CR III for bond strength to aluminium facings in sandwich panels, salt spray environments, resistance to crack propagation and hot, wet environments. The guide gives no numbers for this comparison."
    rating: unknown
    conditions: {comparison: "qualitative statement by the supplier; no test values printed"}
    source: hexcel-guide
    where: "Corrosion-Resistant Coatings section, CR-PAA paragraph (p. 8)"
  - environment: "Heat ageing of 5052 H39 foil at 350 °F (co-cure temperature)"
    headline: "5052 H39 foil lost only 6 percent of its strength after 8 hours at 350 °F."
    effect: "NASA found no difference in tensile properties after 1 or 3 hours at 350 °F. After 8 hours the strength fell by a very slight 6 percent, and the failure strain did not change."
    rating: low
    conditions: {alloy: "5052 H39 foil, 0.0016 in", temperature: "350 °F", times: "1, 3 and 8 hours", atmosphere: "not stated in the report"}
    source: nasa-tm-2018
    where: "Aging studies (350 °F), Figure 3 text"
  - environment: "Heat ageing of 5052 H39 foil at 400 °F (higher cure or service temperature)"
    headline: "5052 H39 foil lost 10 to 15 percent of its strength at 400 °F, and the drop began after 1 hour."
    effect: "At 400 °F the strength dropped right away: 1 and 3 hour ages were both 10 percent below the unaged material, and after 8 hours the strength was 15 percent below the unaged state. NASA says 8 hours at 400 °F may be acceptable if the design can tolerate the drop."
    rating: moderate
    conditions: {alloy: "5052 H39 foil, 0.0016 in", temperature: "400 °F", times: "1, 3 and 8 hours", atmosphere: "not stated in the report"}
    source: nasa-tm-2018
    where: "Aging studies (400 °F), Figure 4 text; Summary"
risks:
  hazards:
    - {text: "PubChem's aggregated ECHA notifications for aluminium list flammable-solid (H228) and water-reaction (H261) statements among the hazards reported. The summary does not separate bulk foil from powder, so it does not describe a honeycomb panel directly.", ghs: [H228, H261], source: pubchem-al, where: "Safety and Hazards, GHS Classification"}
  failure_risks:
    - {mode: "Core crushing under off-axis loads", trigger: "Loads acting off the panel's normal direction; NASA notes that the facings carry most of the load", consequence: "The core can crush. For 5052 at 3.1 pcf, Hexcel's typical crush strength is 130 psi and typical stabilized compressive strength is 335 psi, so the core has far less strength than the facings.", severity: moderate, source: nasa-tm-2018, where: "Summary, discussion of core crushing (report p. 7)"}
    - {mode: "Temper softening during panel cure", trigger: "Core ordered or supplied in an unstabilized temper such as H19 or H191; NASA says the temper is rarely stated on orders", consequence: "The core softens during panel curing, so it may carry less load than the H38 or H39 datasheet values.", severity: moderate, source: nasa-tm-2018, where: "Tempering discussion (report pp. 2-3)"}
    - {mode: "Loss of strength from a hot cure or service exposure", trigger: "Exposure to 400 °F (aging study on 5052 H39 foil)", consequence: "Foil strength was 10 percent lower after 1 hour and 15 percent lower after 8 hours at 400 °F.", severity: moderate, source: nasa-tm-2018, where: "Aging studies, Figure 4 text"}
  side_effects:
    - {text: "The CR III coating is a chromate-based protective layer with an organo-metallic polymer. The Hexcel guide gives no hazard data for it.", affects: "People handling or disposing of coated core (no hazard classification read for the coating)", source: hexcel-guide, where: "Corrosion-Resistant Coatings section (p. 8)"}
  handling:
    - {text: "Hexcel says the core can be supplied machined or formed ready for bonding.", source: hexcel-cr3-ds, where: "Custom Processing, p. 3"}
    - {text: "NASA describes the usual sandwich build: prepreg facings, adhesive and core are bagged, evacuated and co-cured, and the core must be fully bonded to the facings.", source: nasa-tm-2018, where: "Introduction, p. 1"}
  mitigations:
    - {text: "Specify the H38 or H39 temper on the order and check it on receipt, because NASA recommends H38 or H39 for aerospace use.", source: nasa-tm-2018, where: "Summary (report p. 7)"}
    - {text: "Specify CR III for corrosive service. Hexcel's guide names CR-PAA as the better choice where bond strength, salt spray or hot, wet service matters most.", source: hexcel-guide, where: "Corrosion-Resistant Coatings section (p. 8)"}
uses:
  - application: structures
    device: "Sandwich panel core for aerospace structures"
    example: "Hexcel says sandwich structure with honeycomb core gives rigid panels of minimum weight, smooth aerodynamic surfaces and high fatigue resistance in aerospace vehicles and their support equipment. The guide lists satellites, missiles and satellite launch vehicles among the vehicles that use honeycomb."
    source: hexcel-cr3-ds
    where: "Applications, p. 1; Hexcel guide, Applications list (p. 3)"
  - application: structures
    device: "Composite sandwich panel core for manned spaceflight hardware"
    example: "NASA Glenn states that this 5052 core is commonly used as the core of composite sandwich panels, and that material pedigree and documentation matter more for manned spaceflight programmes."
    source: nasa-tm-2018
    where: "Introduction, p. 1"
  - application: structures
    device: "Satellite structural panels (vendor claim)"
    example: "ACP Composites says its AL-X panels are made with HexWeb CR III aluminium honeycomb core in 5052 or 5056 and are widely used in a variety of satellite designs. This is a vendor claim, and no flight record naming this core was read in this run."
    source: acp-al-x
    where: "Product page body text (vendor marketing, qualitative only)"
supply:
  - subject: "Aluminium (primary metal for 5052 and 5056 foil)"
    producers:
      - {country: China, share_percent: 60.8, year: 2025}
      - {country: India, share_percent: 5.7, year: 2025}
      - {country: Russia, share_percent: 5.3, year: 2025}
      - {country: Canada, share_percent: 4.5, year: 2025}
    critical_lists: []
    recycling: "USGS: about 3.6 million tons of aluminium was recovered from purchased scrap in the United States in 2025, about 56% from new scrap and 44% from old scrap."
    substitutes: []
    source: usgs-mcs2026-al
    where: "World Smelter Production and Capacity table, smelter production 2025e (world total 74,000 thousand t as printed; shares calculated by Space Mushroom from the printed figures); Recycling paragraph"
media: []
documents:
  - {title: "Hexcel HexWeb CR III Corrosion Resistant Specification Grade Aluminum Honeycomb, Product Data Sheet (DS 2100)", type: datasheet, url: "https://fileserver.mates.it/Prodotti/4_Anime/TDS/Hexcel/CRIII_US_DS.pdf", year: 2017}
  - {title: "Hexcel HexWeb Honeycomb Attributes and Properties (brochure)", type: datasheet, url: "https://biesterfeld.se/wp-content/uploads/2024/04/HexWeb-Honeycomb-1.pdf", year: 2016}
  - {title: "NASA/TM-2018-219753: Properties of 5052 Aluminum for Use as Honeycomb Core in Manned Spaceflight", type: report, url: "https://ntrs.nasa.gov/citations/20180001568", year: 2018}
  - {title: "PubChem compound record, Aluminum (CID 5359268), GHS classification summary", type: database, url: "https://pubchem.ncbi.nlm.nih.gov/compound/5359268", year: 2026}
  - {title: "Mineral Commodity Summaries 2026, Aluminum", type: report, url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf", year: 2026}
gaps:
  - "Bulk density of the 5052 or 5056 alloy (g/cm3): not printed on the aircraftmaterials 5052 or 5056 pages, and the Smith Metal and Aalco datasheets could not be read in this run. Only the honeycomb core density (3.1 pcf nominal) is given."
  - "Critical-mineral status of aluminium: the 2026 USGS aluminium summary read in this run has no critical-mineral statement, and the USGS or EU critical lists were not opened for this profile."
  - "Crustal abundance of aluminium: not read in this run, so the abundance field is left out."
  - "Environment-specific data for CR III honeycomb (thermal vacuum, low Earth orbit atomic oxygen, radiation, outgassing): none found in the sources read."
  - "Flight heritage: no NASA or ESA flight report naming an aluminium honeycomb core was read. The space-use statements are NASA's manned-spaceflight context, Hexcel's list of satellites, and one vendor claim."
  - "Property names bare_compressive_strength, stabilized_compressive_strength, stabilized_compressive_modulus, crush_strength, plate_shear_strength_l, plate_shear_strength_w, plate_shear_modulus_l and plate_shear_modulus_w are not in spores/property-canon.yaml. Elastic modulus, elongation, yield and tensile names are canonical."
  - "Source disagreements inside the Hexcel documents: the data sheet and the guide differ in a few cells. Example: 5/32 in, 5.3 pcf 5052 stabilized modulus is 15 ksi in the data sheet and 195 in the guide. Example: 3/16 in, 2.0 pcf 5052 plate shear W modulus is 14.3 in the data sheet and 13.3 in the guide. This profile uses only the 3/16 in, 3.1 pcf row, which both documents print with the same values."
  - "Other cell sizes, densities and foil gauges are not included. Only the 3/16 in, 3.1 pcf row is profiled for 5052 and 5056."
  - "The 5056 minimum values and the 5056 shear and crush values at other densities were not added."
  - "No UNS number for 5056 was printed on the page read in this run, so none is listed."
  - "Hazard data rest on the PubChem aggregate for aluminium. No safety data sheet for the CR III coating or for the honeycomb was read in this run."
  - "Salt-spray or humidity results for bare, uncoated aluminium honeycomb: none found in the sources read. The only corrosion number is the CR III retention figure."
  - "Ageing atmosphere (air or inert) and humidity effects were not stated in the NASA report."
  - "Bulk 5052 tensile values (H38) are datasheet values quoted by NASA in Table II. They were not read from a primary datasheet in this run."
  - "Mechanical values were tested at 0.625 in thickness, per the Hexcel table note. No thickness correction is applied."
  - "No image was checked, so the media list is empty."
sources:
  hexcel-cr3-ds:
    title: "HexWeb CR III Corrosion Resistant Specification Grade Aluminum Honeycomb, Product Data Sheet"
    id: "Hexcel ATA 361 US DC17 - DS 2100"
    url: "https://fileserver.mates.it/Prodotti/4_Anime/TDS/Hexcel/CRIII_US_DS.pdf"
    year: 2017
    kind: datasheet
    license: "supplier document, linked not reproduced"
  hexcel-guide:
    title: "HexWeb Honeycomb Attributes and Properties (Hexcel brochure)"
    id: "Hexcel brochure, copyright 2016"
    url: "https://biesterfeld.se/wp-content/uploads/2024/04/HexWeb-Honeycomb-1.pdf"
    year: 2016
    kind: datasheet
    license: "supplier document, linked not reproduced"
  nasa-tm-2018:
    title: "Properties of 5052 Aluminum for Use as Honeycomb Core in Manned Spaceflight"
    id: "NASA/TM-2018-219753 (NTRS 20180001568)"
    url: "https://ntrs.nasa.gov/citations/20180001568"
    year: 2018
    kind: report
    license: "public domain (NASA)"
  aircraftmaterials-5052:
    title: "Aluminium Alloy 5052 / 5052A (aircraftmaterials.com data page)"
    id: "UNS A95052 (printed on page)"
    url: "https://aircraftmaterials.com/data/aluminium/5052.html"
    kind: web
    license: "web page, cited not reproduced"
  aircraftmaterials-5056:
    title: "Aluminium Alloy 5056 / 5056A (aircraftmaterials.com data page)"
    id: "Alloy 5056 USA and 5056A EWAA composition table"
    url: "https://aircraftmaterials.com/data/aluminium/5056.html"
    kind: web
    license: "web page, cited not reproduced"
  pubchem-al:
    title: "PubChem compound record, Aluminum (CID 5359268)"
    id: "CID 5359268"
    url: "https://pubchem.ncbi.nlm.nih.gov/compound/5359268"
    year: 2026
    kind: database
    license: "public domain (NCBI)"
  usgs-mcs2026-al:
    title: "Mineral Commodity Summaries 2026, Aluminum"
    id: "USGS MCS 2026"
    url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-aluminum.pdf"
    year: 2026
    kind: report
    license: "public domain (USGS)"
  acp-al-x:
    title: "AL-X aluminium honeycomb carbon fibre sandwich panel (ACP Composites product page)"
    id: "ACP Composites product page, vendor marketing"
    url: "https://acpcomposites.com/shop/sandwich-panels/aluminum-core-panels/aluminum-carbon-fiber-sandwich-panel"
    kind: web
    license: "web page, cited not reproduced"
license: CC-BY-4.0
updated: "2026-11-01"
review:
  status: draft
  method: assistant
  checked_values: 27
  unreachable: 2
  caveats: 3
  note: "Written by an AI assistant on 2026-11-01 from Hexcel, NASA, PubChem, USGS and supplier pages read in this run. 27 property values were copied from the printed tables and text. Two datasheets (Smith Metal 5052 PDF and Aalco 5052 PDF) could not be read."
story:
  recipe:
    line: "Hexcel makes this core by the expansion method. Sheets of foil with printed adhesive node lines are stacked and cured into a HOBE block (honeycomb before expansion), which is expanded and then sliced to the required thickness (Hexcel guide, How Honeycomb Is Manufactured). The foil is a 5052 or 5056 aluminium-magnesium alloy, and each core carries the CR III coating."
    parts:
      - {name: "Aluminium-magnesium alloy 5052 foil", symbol: "Al-Mg", share: "Mg 2.2 to 2.8 wt%; Cr 0.15 to 0.35 wt% (NASA Table I, AMS4004D chemistry)", role: "The standard structural foil. Magnesium hardens it, and the core is supplied in the H39 temper."}
      - {name: "Aluminium-magnesium alloy 5056 foil", symbol: "Al-Mg", share: "Mg 4.50 / 5.6 wt% (aircraftmaterials 5056 composition table)", role: "The stronger alternative. Hexcel says 5056 honeycomb strength is about 20 percent greater than 5052 of the same cell, foil and density."}
      - {name: "CR III coating", share: "Thickness not stated in the sources read", role: "A chromate-based protective layer under an organo-metallic polymer. Hexcel says it keeps protection at elevated temperatures."}
  risk_groups:
    - title: "For people"
      level: 0
      verdict: "No hazard classification for the core in the sources read"
      lead: "The core is aluminium with a coating. The sources read give no hazard classification for the finished core, and the only hazard entries are PubChem's aggregate for aluminium forms."
      points:
        - label: "The metal"
          line: "PubChem's aggregated ECHA notifications for aluminium list flammable-solid (H228) and water-reaction (H261) statements, but the summary does not separate bulk foil from powder."
        - label: "The coating"
          line: "CR III contains a chromate-based layer. Hexcel's guide gives no hazard data for it, so check the supplier's safety data sheet before cutting or disposing of coated core."
    - title: "If a panel is cured hot or overloaded"
      lead: "These results come from laboratory tests on foil and from supplier data, not from field failures."
      points:
        - label: "Cure at 350 °F"
          line: "NASA's 5052 H39 foil lost 6 percent of its tensile strength after 8 hours at 350 °F, a common co-cure temperature."
        - label: "Cure at 400 °F"
          line: "At 400 °F the foil lost 10 percent of its strength after 1 hour and 15 percent after 8 hours."
        - label: "Off-axis loads"
          line: "Loads that act off the panel's normal direction can crush the core. For 5052 at 3.1 pcf, Hexcel's typical crush strength is 130 psi."
    - title: "Handling and temper"
      points:
        - label: "Temper"
          line: "NASA recommends the H38 or H39 temper for aerospace use and says the temper should be stated on the order and checked on receipt."
        - label: "Machining"
          line: "Hexcel says the core can be supplied machined or formed ready for bonding."
  why: >-
    Aluminium honeycomb core is the lightweight middle layer of a sandwich panel. Two thin facings carry most of the load,
    and the honeycomb holds them apart, which raises stiffness for little added weight. Hexcel's CR III version adds a
    corrosion-resistant coating to 5052 or 5056 foil. It is used in aerospace structures where minimum weight, smooth
    rigid panels and fatigue resistance matter.
  uses:
    - where: "Aerospace structures"
      line: >-
        Hexcel says sandwich structure with honeycomb core gives rigid panels of minimum weight, aerodynamic smooth surfaces
        and high fatigue resistance in aerospace vehicles and their support equipment. Its guide lists satellites, missiles
        and satellite launch vehicles among the vehicles that use honeycomb.
    - where: "Manned spaceflight panels"
      line: >-
        NASA Glenn's report on the 5052 core says it is commonly used in composite sandwich panels for lightweight
        structures. It adds that the core's documentation and pedigree matter more for manned spaceflight programmes.
    - where: "Satellite panels (vendor claim)"
      line: >-
        ACP Composites says its AL-X panels use HexWeb CR III core in 5052 or 5056 and are widely used in satellite designs.
        This is a vendor claim, and no flight record naming this core was read in this run.
  can_do:
    - label: "Compressive strength"
      benchmark: stabilized_compressive_strength
      line: >-
        A 5052 core of 3/16 in cell at a nominal 3.1 pcf has a typical stabilized compressive strength of 335 psi and a minimum
        average of 215 psi, per Hexcel's data sheet.
    - label: "Shear strength"
      benchmark: plate_shear_strength_l
      line: >-
        For the same 5052 core, plate shear strength in the L (ribbon) direction is 210 psi typical and 155 psi minimum.
    - label: "Corrosion protection"
      value: "About 88 percent retained"
      line: >-
        After 350 °F heat ageing for up to 500 hours and 30 days of salt spray, CR III keeps about 88 percent of its
        room-temperature shear strength, per Hexcel's data sheet.
    - label: "Thermal expansion"
      benchmark: cte
      line: >-
        The coefficient of thermal expansion is 13.2 x 10^-6 inch/inch-°F for CR III 5052 and 5056 honeycomb, per Hexcel's
        guide.
  compare: >-
    Among honeycomb cores, the aluminium types are the metallic choice. Hexcel's comparison table rates PVC foam as having
    relatively low crush strength and stiffness, and rates honeycomb as excellent in both. Within aluminium, 5056 is about 20
    percent stronger than 5052 for the same cell, foil and density, according to the Hexcel guide. The data sheet and the
    guide disagree on a few table cells, so quote the exact cell you use.
  compare_rows:
    - {label: "Core density, nominal, 3/16 in cell, 5052", benchmark: density}
    - {label: "Stabilized compressive strength, typical, 5052", benchmark: stabilized_compressive_strength}
    - {label: "Coefficient of thermal expansion", benchmark: cte}
  handling:
    - "Order the H38 or H39 temper by name and check it on receipt. The data sheet says the core is supplied in H39, but orders often do not state the temper."
    - "Specify CR III for corrosive service. Hexcel's guide says CR-PAA is better for bond strength and hot, wet service."
    - "Watch the cure temperature. In NASA's foil study, 8 hours at 350 °F cost 6 percent of strength, and 400 °F cost 10 to 15 percent."
  good_for:
    - "Stiff, light sandwich panels in aerospace structures. Hexcel's typical stabilized compressive strength for 5052 at 3.1 pcf is 335 psi."
    - "Corrosion-resistant cores. CR III keeps about 88 percent of its room-temperature shear strength after 350 °F ageing and 30-day salt spray."
  watch_out:
    - "Temper. Strength depends on the temper, and a core that is not stabilized can soften during cure, according to NASA."
    - "Crush. Core crush strength is low (130 psi typical for 5052 at 3.1 pcf), so off-axis loads need design care."
    - "Cure temperature. At 400 °F the foil loses 10 to 15 percent of its strength in NASA's study."
    - "Datasheet disagreement. Hexcel's guide and data sheet differ in a few table cells, so quote the cell you use."
  verdict: "Aluminium honeycomb core with the CR III coating is well documented. Hexcel gives the design data, and NASA's study shows that temper and cure temperature control its strength. The sources read support use in aerospace structures, but none is a flight record for this core."