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ASTM D1002 Complete Guide: Lap Shear Test Specimens, Loading Rate, Grips and Shear Strength

Writer: Chris Thomas
Chris Thomas
1 day ago
20 min read

ASTM D1002 is the standard lap shear test for adhesives bonded to metal, and it is the number printed on almost every structural adhesive data sheet. It looks simple: bond two metal strips with a 12.7 mm overlap, pull them apart and divide the peak load by the bonded area. In practice the result depends as much on surface preparation, bondline thickness, overlap accuracy, grip alignment and load rate as on the adhesive, and a misaligned specimen can fail well below its real strength. This complete guide covers specimen and panel dimensions, adherends, surface preparation, conditioning, the loading rate, how to size the testing machine for real structural adhesive loads (a Mark-10 tester or a Galdabini universal testing machine), grips, spacers and offset jaws, where video extensometers fit, the calculation with a worked example, failure modes, testing at temperature, ISO 4587, troubleshooting and a full FAQ, with videos from our lab.

For the standard reference page, see our ASTM D1002 lap shear test page. For how lap shear compares with block shear, read lap shear vs. block shear: ASTM D1002, D905 and D4501. This article focuses on running the test and choosing the equipment.

ASTM D1002 at a glance

  • Full title: Standard Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading (Metal-to-Metal). The current edition is D1002-10, reapproved in 2019.

  • What it measures: the failing load of a single-lap joint divided by the bonded area, reported as apparent shear strength in MPa (psi).

  • Specimen: two metal strips 25.4 mm (1.00 in) wide and 101.6 mm (4.0 in) long, bonded with a 12.7 ± 0.25 mm (0.50 ± 0.01 in) overlap, for a bond area of about 322.6 mm² (0.50 in²).

  • Recommended adherend: 1.62 ± 0.125 mm (0.064 ± 0.005 in) sheet, most often 2024-T3 aluminum. Brass, copper, steel, stainless steel and titanium are also listed.

  • Gripping: the outer 25.4 mm (1 in) of each end in self-aligning grips, with 63.5 mm (2.5 in) between each jaw and the overlap.

  • Loading rate: 80 to 100 kgf/cm² (1,200 to 1,400 psi) of shear area per minute, about 7.8 to 9.8 MPa/min, or roughly 1.3 mm/min (0.05 in/min) crosshead speed.

  • Result: τ = F ÷ (L × b), maximum load divided by measured overlap length times width.

  • Always report: the failure mode (cohesive, adhesive or adherend failure) with estimated percentages, plus bondline thickness and overlap.

  • Typical equipment: a tester sized for 5 to 25 kN depending on the adhesive, wedge grips with spacers or offset jaws, and a load cell that also resolves weak bonds.

ASTM D1002 single-lap joint specimen and lap joint types diagram

What ASTM D1002 measures and who uses it

A lap joint is the simplest way to load an adhesive in shear between two rigid adherends, and it resembles many real joints: a bracket bonded to a panel, a stiffener bonded to a skin, a hem flange in a car door. Adhesive manufacturers, aerospace and automotive bonding engineers, medical-device assemblers and electronics manufacturers run D1002 first when they qualify an adhesive or check a surface treatment.

The word "apparent" matters. The load on a single-lap joint is offset by one adherend thickness, so the joint rotates as it loads and the overlap ends see peel as well as shear. Shear stress also peaks at the ends of the overlap rather than spreading evenly. The number you calculate is an average, so the standard is clear about how to use it:

  • It is a comparative test, excellent for comparing adhesives, surface preparations, primers, cure cycles and environmental durability, and for production control of a bonding process.

  • It is not a design allowable. Results change with adherend, thickness, overlap and bonding process, so joint design needs analysis or tests of the real joint.

  • Geometry changes the number. A longer overlap carries more load but gives a lower average stress, and thicker adherends rotate less and usually read higher. Never compare D1002 values from different geometries.

ASTM Guide D4896 covers how to interpret single-lap results and is worth reading before you build a qualification program on them.

ASTM D1002 specimen dimensions and adherends

Most labs and data sheets use the standard geometry exactly as written. Figures 1 and 2 in the current edition are the reference for tolerances.

  • Width: 25.4 mm (1.00 in), measured to the nearest 0.25 mm (0.01 in).

  • Overlap: 12.7 ± 0.25 mm (0.50 ± 0.01 in) for 1.62 mm metal, measured on every specimen after bonding.

  • Adherend length: 101.6 mm (4.0 in) each, for an assembled specimen about 190.5 mm (7.5 in) long.

  • Adherend thickness: 1.62 ± 0.125 mm (0.064 ± 0.005 in) recommended.

  • Free length: 63.5 mm (2.5 in) between each jaw and the overlap. The standard lets the overlap vary but not this distance.

  • Edges: cut or machined smooth with no burrs, which start cracks at the overlap ends.

Recommended metals

The standard recommends 2024-T3 aluminum (ASTM B209), brass, copper, carbon steel, Type 302 stainless steel and titanium, each to its ASTM material specification. 2024-T3 is by far the most common, because aerospace adhesive specifications grew up around it. If your product bonds a different metal, test that metal, but report it and do not compare the result with aluminum data.

Why 12.7 mm, and when to change the overlap

The overlap is chosen so the adhesive fails before the metal yields. A 25.4 × 1.62 mm strip of 2024-T3 has a 41.1 mm² cross-section, and at a yield strength of roughly 345 MPa it starts to yield at about 14 kN, an average shear stress of about 44 MPa on the 322.6 mm² bond. D1002 gives a formula for the maximum overlap with other metals or thicknesses:

  • L = Fty × t ÷ τ, where L is the overlap, Fty the yield strength of the metal, t the adherend thickness and τ 150 % of the estimated average shear strength of the adhesive.

  • Example: for 2024-T3 at Fty ≈ 345 MPa, t = 1.62 mm and an adhesive expected to reach 30 MPa, τ = 45 MPa and L = 345 × 1.62 ÷ 45 ≈ 12.4 mm, which is why 12.7 mm suits most structural adhesives.

  • Very strong adhesives on thin or soft metal need a thicker or stronger adherend, or a shorter overlap. Report any change and compare results only within one geometry.

Making the specimens: panels, surface preparation and cure

Most lap shear scatter is created before the specimen reaches the testing machine. A perfectly run test on a poorly made joint measures the joint, not the adhesive.

Panels or individual specimens

  • Panel method: two sheets are bonded along one edge with the 12.7 mm overlap in a fixture that holds overlap and alignment, then cut into 25.4 mm strips after cure, discarding the edges. A panel about 178 mm (7 in) wide yields five specimens; the standard calls for specimens in multiples of at least five.

  • Individual (finger) specimens: pre-cut strips are bonded one at a time in a jig. This avoids sawing through the bondline, but each joint needs its own alignment and overlap check.

  • Bonding jigs: use stops that set the overlap to ±0.25 mm and keep the strips coplanar. Twisted or offset joints load the bond in peel and torsion and fail early.

Surface preparation

D1002 leaves surface preparation to the user and to the adhesive or process specification, and it is the variable the test most often evaluates. Write it down in detail and keep it identical across every panel you compare. Common preparations, in rough order of durability:

  • Solvent wipe only: quick but weak and variable; screening only.

  • Abrade and solvent clean: grit blast or abrasive pad, then a clean solvent wipe, bonding within the open time your process allows.

  • Chemical treatments for aluminum: FPL etch (ASTM D2651), phosphoric acid anodizing (ASTM D3933) and sol-gel treatments give the highest and most durable bonds on 2024-T3.

  • Primers: many structural film adhesives are tested over a bond primer. Report the primer, its thickness and cure.

Applying the adhesive and controlling the bondline

  • Coverage: spread adhesive about 6 mm (1/4 in) beyond the overlap, then remove squeeze-out or leave a fillet, the same way every time. Fillets raise apparent strength.

  • Bondline thickness: control it with glass beads, a film-adhesive carrier or jig shims, and report the average to 0.025 mm (0.001 in). Thick bondlines usually lower lap shear strength.

  • Cure: follow the manufacturer's temperature, pressure, time and ramp exactly and record them. Under-cured epoxies give low, rubbery failures.

  • After cutting: deburr the edges and measure overlap and width on every specimen.

Conditioning

  • D1002 asks for testing as soon as practical after preparation unless the adhesive manufacturer specifies a conditioning period. Many two-part adhesives keep curing for days, so test at a defined time after mixing and record it.

  • Most labs condition and test at 23 °C and 50 ± 10 % RH unless the adhesive or customer specification says otherwise.

  • For durability work, expose specimens to humidity, salt fog, fluids or thermal cycling and compare them with unexposed controls from the same panels. ASTM D1151 covers the effect of moisture and temperature on bonds.

  • Moisture-sensitive adhesives can change strength within hours of leaving a humidity chamber, so test within a fixed window.

ASTM D1002 loading rate and machine requirements

D1002 specifies a loading rate of 80 to 100 kgf/cm² (1,200 to 1,400 psi) of shear area per minute, about 7.8 to 9.8 MPa/min. On a 322.6 mm² bond that is roughly 2.5 to 3.2 kN per minute, so a 20 MPa adhesive fails in two to two and a half minutes. The standard notes that a free crosshead speed of about 1.3 mm/min (0.05 in/min) approximates this rate, and most labs run in crosshead control at 1.3 mm/min.

  • Rate control: a machine with closed-loop load control can run the stress rate directly. In crosshead control, check the load-time slope on the first specimen; machine stiffness, grip seating and adherend stretch all change how crosshead speed becomes load rate.

  • Load cell range: older editions ask for the failing load to fall between 15 % and 85 % of full scale. With load cells verified to ASTM E4 over a wide range, the practical rule is to keep the failing load inside the verified range, with good resolution for weak adhesives.

  • Capacity: set by the strongest adhesive and adherend you will test. See below.

  • Travel and data rate: specimens fail within a few millimetres, so any tester with room for the 190 mm specimen and grips is enough, and 10 Hz or more captures the peak at this speed.

Which testing machine for ASTM D1002: Mark-10 or Galdabini?

Size the machine from the failing load: apparent shear strength times bond area. Using the typical values later in this guide, flexible adhesives fail below about 2 kN on the standard bond, polyurethanes and cyanoacrylates at roughly 1.5 to 8 kN, and structural epoxies and acrylics routinely exceed 5 to 10 kN, reaching 13 kN or more on treated aluminum. Steel or titanium adherends, wider specimens and longer overlaps push loads higher still.

Mark-10 tensile testers: lower-strength adhesives and QC

A Mark-10 motorized test frame is an economical, compact choice for lap shear QC when failing loads are known and fall well within the frame capacity. On the standard 322.6 mm² bond, full capacity corresponds to:

  • 100 lb (F105), about 450 N: about 1.4 MPa. Sealants and very weak bonds only.

  • 300 lb (F305), about 1.3 kN: about 4.1 MPa. Hot melts, silicones and flexible adhesives.

  • 500 lb (F505), about 2.2 kN: about 6.9 MPa. Flexible and semi-structural adhesives.

  • 750 lb (F755), about 3.3 kN: about 10.3 MPa. Polyurethanes and lower-strength cyanoacrylates.

  • 1,500 lb (F1505), about 6.7 kN: about 20.7 MPa. Many cyanoacrylates, MS polymers, polyurethanes and lower-strength acrylics.

Keep a margin: a 20 MPa adhesive puts the F1505 at full capacity, and a strong batch will overload it. Two more points:

  • Speed: the standard speed range of every F-series frame starts well above 1.3 mm/min, so specify Mark-10's optional low-speed range when you order a frame for D1002.

  • Grips: use compact wedge or vise grips with spacers on the right grip adapters. All F-series frames hold speed to ±0.2 % and sample load at 5,000 Hz, so brittle failures are captured cleanly.

Mark-10 F505-EM 500 lb tensile tester, suited to lap shear QC of flexible and lower-strength adhesives

Compare the two machine types in Mark-10 test frame vs. universal testing machine, and see every model on the tensile testers page.

Galdabini universal testing machines: structural adhesives and full adhesive labs

For structural adhesives, qualification work, testing at temperature and labs that also run peel, block shear and tensile tests, choose a Galdabini benchtop universal testing machine:

  • 10 kN: covers adhesives up to about 30 MPa on the standard bond, with ASTM D903 and ASTM D1876 peel on the same frame.

  • 25 kN: the safe choice for structural adhesive development, covering toughened epoxies and film adhesives up to the yield of the aluminum adherend, plus steel and titanium adherends, in line with our advice to size grips and load cell for at least 20 kN.

  • 50 kN: for thick steel adherends, wide and double-lap specimens, ASTM D4501 block shear and metals tensile testing. Our 50 kN wedge grips are made for lap shear, metals and reinforced plastics.

UTM software stores a D1002 method with the bond area entered per specimen, runs the stress rate or 1.3 mm/min, and records the failure mode with each result. See our universal testing machine buyer's guide or browse benchtop UTMs.

Quick comparison

  • Choose a Mark-10 for QC of sealants, hot melts, flexible adhesives, polyurethanes and cyanoacrylates whose failing loads stay well under 6.7 kN, with the low-speed option.

  • Choose a Galdabini UTM for structural epoxies, acrylics and film adhesives, steel and titanium adherends, testing from −80 to +280 °C, stress-rate control, and labs running peel, block shear and tensile methods too.

Grips for ASTM D1002: wedge grips, spacers and offset jaws

The two adherends of a lap shear specimen sit in different planes, offset by one adherend thickness plus the bondline. Clamp each end in an ordinary grip centred on the load line and the specimen bends before any load is applied, adding peel at the overlap ends. D1002 calls for self-aligning grips holding the outer 25.4 mm of each end, and good practice is to put the load line through the bondline from the start.

Spacers (shims) and offset jaws

The simplest fix is a spacer the same thickness as the adherend, placed in each grip on the opposite side of the specimen from the other adherend, so both tabs sit in the plane of the bondline. Many labs bond a spacer tab to each end with the same adhesive so it cannot slip. Keep a set for each adherend thickness. Grips with jaw faces that shift sideways by one adherend thickness avoid loose spacers and are faster in production. Either way, the specimen should hang straight, with no visible bend at the overlap, before you load it.

Which grip type?

  • Wedge grips: the usual choice for D1002. The wedge tightens as load rises, serrated faces hold aluminum, steel and titanium without slipping, and our 10 to 50 kN sizes cover every lap shear load. Jaw breaks are rare because the adhesive fails far below the metal's strength.

  • Vise grips: screw-action grips with serrated faces suit lower-strength adhesives on Mark-10 testers. Shim the opposite face, tighten evenly and watch for slip on smooth or oily metal.

  • Pneumatic grips: constant, repeatable clamping for high-volume QC. Our 2.4 kN and 2.6 kN models suit weak bonds and plastic lap shear, not structural metal joints.

  • Hydraulic grips: for thick adherends and high-volume structural testing.

  • Roller grips are designed for flexible materials and are not used for metal lap shear.

Use coarse serrated faces and replace worn ones, set a stop or marked line so the gripped and free lengths are identical every time, and let a universal joint or self-aligning coupling settle the load string. Our grips fit Instron, MTS, ZwickRoell, Shimadzu, Tinius Olsen and Mark-10 frames with the right grip adapters. See the shear fixtures page and the tensile grip and fixture selection guide for the full range.

Do you need an extensometer for ASTM D1002?

No. D1002 reports a failing load and an apparent shear strength, so the standard does not require strain or displacement measurement. Crosshead travel is fine for a load-extension plot, but it mostly measures grip seating, adherend stretch and joint rotation, not shear strain in a 0.1 mm bondline, so never report it as adhesive strain. Non-contact measurement still adds value in an adhesive lab:

  • Joint displacement without machine compliance. A video extensometer tracking targets on each adherend beside the overlap records the movement of the joint itself, separating adhesive behaviour from grip slip and frame stiffness.

  • Joint rotation and peel at the overlap ends. The UGC-VE-4105 3D stereo video extensometer captures out-of-plane movement and full-field strain, which is exactly what single-lap rotation produces. Useful in research and when a joint fails earlier than expected.

  • Documenting failures. A recording of every test shows where the failure started and supports the failure-mode percentages in the report.

  • Design data needs another test. For adhesive shear stress-strain properties, use thick-adherend lap shear (ASTM D5656) with a dedicated displacement gauge, not D1002.

UGC-VE 4000 series video extensometer tracking specimen deformation without contact, as used to record lap joint displacement and rotation

A single-camera UGC-VE-2109 covers a full lap shear specimen at room temperature or through a chamber window. Clip-on extensometers are rarely used because the brittle failure can damage them. Read the video extensometer buying guide and types of extensometers.

ASTM D1002 test procedure, step by step

  • Step 1: Prepare surfaces, bond panels or individual specimens in an alignment jig and cure exactly as specified, in multiples of at least five.

  • Step 2: Cut panels into 25.4 mm strips, deburr, and label each specimen with its panel and position.

  • Step 3: Measure width and overlap to the nearest 0.25 mm and the bondline thickness; calculate the bond area.

  • Step 4: Condition the specimens and record the time since cure.

  • Step 5: Fit spacers or set the offset jaws. Mount the specimen with 25.4 mm in each grip and 63.5 mm free on each side, hanging straight.

  • Step 6: Zero the load with the specimen in the upper grip only, close the lower grip and remove any preload.

  • Step 7: Load at 7.8 to 9.8 MPa/min, or about 1.3 mm/min, until the joint fails.

  • Step 8: Record the maximum load. Inspect both fracture surfaces, estimate the percentages of cohesive, adhesive and adherend failure, and photograph them.

  • Step 9: Calculate the apparent shear strength for each specimen and the average, maximum, minimum and standard deviation for the set.

ASTM D1002 calculation and worked example

  • Apparent shear strength: τ = F ÷ A, where F is the maximum load and A = L × b, the measured overlap length times the measured width.

  • Units: N ÷ mm² = MPa. Multiply MPa by 145.04 for psi; divide kgf/cm² by 10.197 for MPa.

  • Report the failing load too, so readers can see where it sat in the load cell range.

Worked example: a toughened epoxy on FPL-etched 2024-T3. The specimen measures 25.40 mm wide with a 12.85 mm overlap, so A = 25.40 × 12.85 = 326.4 mm². It fails at 7,180 N, so τ = 7,180 ÷ 326.4 = 22.0 MPa (about 3,190 psi or 224 kgf/cm²). The surfaces show about 90 % cohesive failure and 10 % adhesive failure at one edge.

Checking the loading rate: at 7.8 to 9.8 MPa/min, a 22.0 MPa bond should fail in about 2.2 to 2.8 minutes. If it broke in 50 seconds at 1.3 mm/min, the setup is stiffer than the standard assumed; reduce the speed or switch to load-rate control.

Set statistics: five specimens from one panel give 22.0, 21.4, 23.1, 20.6 and 22.5 MPa. The average is 21.9 MPa, minimum 20.6 and maximum 23.1 MPa, with a standard deviation of about 1.0 MPa (a coefficient of variation of about 4.4 %).

Typical apparent shear strength values

Typical ranges on the standard geometry with good surface preparation, from manufacturers' published data. A sanity check, not a specification:

  • Silicones, MS polymers and sealants: about 1 to 3 MPa (150 to 450 psi).

  • Hot melts and flexible polyurethanes: about 2 to 8 MPa (300 to 1,200 psi).

  • Cyanoacrylates on metal: about 10 to 25 MPa (1,500 to 3,600 psi), often lower on aluminum than on steel.

  • Structural acrylics and two-part epoxies: about 15 to 30 MPa (2,200 to 4,400 psi).

  • Toughened heat-cured epoxies and film adhesives on treated aluminum: about 30 to 40 MPa (4,400 to 5,800 psi), close to the yield of the 1.62 mm adherend.

Failure modes: adhesive, cohesive and substrate failure

D1002 requires the nature of the failure for each specimen, as estimated percentages of the bond area. The failure mode often tells you more than the number:

  • Cohesive failure: the fracture runs through the adhesive, leaving adhesive on both surfaces. This is the target: the result reflects the adhesive.

  • Adhesive (interfacial) failure: the adhesive comes cleanly off one surface. This points to surface preparation, contamination or primer problems, and such joints usually degrade badly in humidity.

  • Mixed failure: estimate the percentages by area; a photograph with a grid overlay makes this repeatable. Some labs record thin-layer cohesive failure separately, as it can indicate a weak boundary layer.

  • Adherend (substrate) failure: the metal yields or breaks first. The result is a lower bound on joint strength, not an adhesive strength; use a thicker or stronger adherend or a shorter overlap.

ISO 10365 gives standard designations for these failure patterns, and many labs use them with D1002 so reports are consistent between sites.

Precision and scatter

Older editions of D1002 state that precision and bias had not been determined, so check the current edition for interlaboratory data. In practice, well-controlled bonds on chemically treated aluminum often give coefficients of variation around 5 % or less within a panel, while abraded or solvent-wiped surfaces often scatter by 10 to 15 % or more. Most scatter comes from specimen preparation; in the test itself, misalignment and grip slip are the main causes.

Older editions also ask for at least 30 specimens representing at least four joints when characterizing an adhesive. Routine QC typically uses five or more specimens per condition. Draw them from more than one panel, because panel-to-panel variation is usually larger than variation within a panel.

Testing lap shear at high and low temperature

  • Aerospace and automotive specifications often call for lap shear at a cold temperature such as −55 °C and one or more elevated temperatures, plus hot/wet conditions. Many adhesives lose most of their strength above their glass transition temperature.

  • Use an environmental chamber on the frame; ours run from −80 to +280 °C. Put a thermocouple at or near the bondline and soak for the time your specification requires.

  • Use grips and spacers rated for the temperature, or extension rods that keep the grips outside the hot zone.

  • Report the test temperature, soak time and any humidity exposure. See the temperature chamber buyer's guide.

What to report

  • The standard and edition, and any deviation from the standard geometry or rate.

  • Adhesive identification and lot; adherend metal, temper, thickness and surface preparation; primer if used.

  • Bonding and cure conditions, time between cure and test, and conditioning.

  • Average bondline thickness (to 0.025 mm) and the overlap length.

  • Test temperature and loading rate or crosshead speed.

  • Number of specimens and of panels or joints represented.

  • Maximum, minimum and average failing loads and shear strengths, ideally with standard deviation.

  • Failure mode of each specimen, with estimated percentages of cohesive, adhesive and adherend failure.

Common ASTM D1002 problems and how to fix them

  • Low strength with clean metal on one side: poor surface preparation or contamination. Review cleaning, abrasion, etch or primer and the time to bonding.

  • Specimens bend before loading: no spacers or offset. Fit spacers equal to the adherend thickness or use offset jaws.

  • Lower than the data sheet: different adherend, thinner metal, longer overlap, no fillet, thicker bondline or incomplete cure. Match the data sheet geometry first.

  • Metal yields beside the overlap: the adherend is too weak for the adhesive. Use thicker or stronger metal, or shorten the overlap within the L = Fty × t ÷ τ rule.

  • Slipping tabs and saw-tooth traces: worn faces or oily metal. Clean the tabs and use coarse serrated wedge grips.

  • Wrong rate: running a machine's default 13 or 50 mm/min. Use 7.8 to 9.8 MPa/min or about 1.3 mm/min.

  • Nominal instead of measured area: a 13.2 mm overlap instead of 12.7 mm shifts the result by 4 %. Measure every specimen.

  • Overloaded tester: a structural epoxy on a 1,500 lb frame. Size from the strongest adhesive you test.

  • No failure mode recorded: without it you cannot tell whether you measured the adhesive or the surface treatment.

ASTM D1002 vs. ISO 4587 and related ASTM methods

ISO 4587 (EN 1465 in Europe) is the closest international equivalent: 25 mm wide, 100 mm long adherends, typically 1.6 mm aluminum, with a 12.5 mm overlap. Instead of a stress rate it sets a constant speed so the joint fails in about a minute (65 ± 20 s in the 2003 edition). Results are similar but not interchangeable, so report which standard you used.

  • ASTM D5868: lap shear for fiber-reinforced plastic bonding, with a 25.4 mm overlap and a faster rate.

  • ASTM D3163 and D3164: lap shear of bonded rigid plastics.

  • ASTM D3165: single-lap shear of laminated assemblies, notched from a bonded panel.

  • ASTM D3528: double-lap shear, which cancels most single-lap bending.

  • ASTM D5656: thick-adherend lap shear for adhesive shear stress-strain design data.

  • ASTM D905 and ASTM D4501: block shear of wood and rigid substrates. See lap shear vs. block shear.

  • ASTM C273: shear of sandwich core materials bonded between plates.

Related adhesive tests: peel, tension and cleavage

Most data sheets pair lap shear with a peel test, because adhesives that are strong in shear can be weak in peel, and peel is how many bonds fail in service.

Complete ASTM D1002 equipment packages

Basic QC station (flexible and lower-strength adhesives)

Advanced structural adhesive lab

UGC-VE-2100 series single-camera video extensometer for recording adhesive lap joint displacement and failure

ASTM D1002 FAQ

What is ASTM D1002?

The ASTM test method for apparent shear strength of single-lap-joint adhesively bonded metal specimens by tension loading. Two metal strips bonded with a 12.7 mm overlap are pulled apart, and the maximum load divided by the bond area gives the apparent shear strength.

What are the ASTM D1002 specimen dimensions?

Each adherend is 25.4 mm (1 in) wide and 101.6 mm (4 in) long, typically 1.62 mm (0.064 in) 2024-T3 aluminum, bonded with a 12.7 ± 0.25 mm (0.5 in) overlap for a bond area of about 322.6 mm².

What is the ASTM D1002 test speed?

A loading rate of 80 to 100 kgf/cm² (1,200 to 1,400 psi) per minute, about 7.8 to 9.8 MPa/min. A crosshead speed of about 1.3 mm/min (0.05 in/min) approximates it.

How is lap shear strength calculated?

Maximum load divided by measured bond area: τ = F ÷ (L × b). For example, 7,180 N on a 25.40 × 12.85 mm bond (326.4 mm²) gives 22.0 MPa.

Why is it called apparent shear strength?

Because the joint rotates under load, the overlap ends see peel, and shear peaks at the ends of the overlap. F ÷ A is an average that depends on the geometry, not a pure material shear strength.

Do I need spacers or shims for ASTM D1002?

Yes, or offset jaws. The adherends are offset by one thickness, so spacers equal to the adherend thickness put the load line through the bondline. Without them the specimen bends before loading and fails early.

What grips are best for ASTM D1002?

Mechanical wedge grips with coarse serrated faces and spacers or offset jaws. Vise grips suit lower-strength adhesives, pneumatic grips suit high-volume QC of weak bonds, and hydraulic grips suit thick adherends.

What load capacity do I need for lap shear testing?

Multiply expected strength by the 322.6 mm² bond area. Flexible adhesives fail below about 2 kN, but structural epoxies and acrylics reach 5 to 13 kN, so a 10 to 25 kN UTM is usual, and 50 kN suits thick steel adherends and block shear.

Can I run ASTM D1002 on a Mark-10 tester?

Yes, when failing loads stay well within capacity: the F1505 (6.7 kN) reaches about 20 MPa on the standard bond. Order the low-speed option for 1.3 mm/min. Structural adhesives need a Galdabini UTM.

What failure modes must be reported?

The nature of failure for each specimen, as estimated percentages of cohesive failure in the adhesive, adhesive failure at the interface and any adherend failure. Adherend yielding means the result is not an adhesive strength.

How many specimens should I test?

Make specimens in multiples of at least five. Older editions ask for at least 30 from at least four joints to characterize an adhesive; routine QC usually tests five or more per condition from more than one panel.

Do I need an extensometer for ASTM D1002?

No. The result is load divided by area. A video extensometer or 3D DIC adds value for joint displacement without machine compliance, joint rotation, failure records and chamber testing.

Is ASTM D1002 the same as ISO 4587?

They are close equivalents with very similar specimens, but ISO 4587 uses a 12.5 mm overlap and a speed set by time to failure, while D1002 uses a stress rate. Report which standard you used.

Related reading

Get a complete ASTM D1002 system

Universal Grip supplies everything for ASTM D1002 and the rest of your adhesive program: wedge, vise, pneumatic and hydraulic grips with spacers or offset jaws, lap and block shear fixtures, peel fixtures, grip adapters, environmental chambers, video extensometers, and testing machines from a Mark-10 tensile tester to a full Galdabini universal testing machine. Tell us your adhesives, adherends, expected failing loads and temperature range, and we will configure a lap shear system and quote it. Contact us.

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