Shear Testing of Materials
Significance and Purpose
Shear Testing evaluates a material’s resistance to shear stress, measuring properties such as shear modulus, shear strength, and strain at failure. It is critical for materials used in applications where shear loads are significant, such as composites, polymers, and structural materials. Various ASTM and ISO standards define procedures for measuring shear properties in different material types, ensuring consistency and reliability in testing.
Shear testing is used for:
- Material Characterization: Determines shear modulus, shear strength, and failure modes.
- Quality Control: Ensures materials meet design specifications.
- Failure Analysis: Identifies shear failure mechanisms in materials and structures.
- Engineering Design: Supports calculations for shear loading in structural and mechanical components.
- Research & Development: Helps in optimizing material formulations for improved shear performance.
Relevant ASTM and ISO Standards
General Shear Testing Standards
- ISO 15310: In-plane shear modulus via plate twist method.
- ASTM D412, ASTM D638, ISO 527-1: Orthotropic in-plane shear modulus (calculated from tensile moduli and Poisson’s ratios).
- ASTM D732: Shear strength of materials using punch tool.
- ASTM D5379: Shear stress-strain measurement using the Iosipescu method.
- ASTM D7078/D7078M: Shear stress-strain measurement using the rail shear method.
- ASTM D2344, ISO 14130: Short-beam shear strength for general materials.
Shear Testing Standards for Composite Materials
- ASTM D5379/D5379M: Shear stress-strain testing for composite materials using the Iosipescu method.
- ASTM D2344/D2344M: Short-beam shear strength testing for composites.
- ASTM D3518/D3518M: In-plane shear stress-strain testing via tensile testing of a ±45° laminate.
DatapointLabs Tests for Shear Testing
Tests in the DatapointLabs test catalog that reference shear testing are as follows:
General Shear Testing (inquire regarding material suitability)
| Test ID | Test Description | Standards |
|---|---|---|
| M-017 | In-Plane Shear Modulus (Plate Twist Method) | ISO 15310 |
| M-013 | Orthotropic In-Plane Shear Modulus (Includes M-010, M-101) | ASTM D412, ASTM D638, ISO 527-1 |
| M-038 | Shear Strength | ASTM D732 |
| M-219 | Shear Stress-Strain | ASTM D5379 |
| M-219RS | Shear Stress-Strain using Rail Shear method | ASTM D7078/D7078M-20e1 |
| M-041 | Lap Shear Strength | Proprietary Specification |
Shear Testing Specific to Composites
| Test ID | Test Description | Standards |
|---|---|---|
| M-034C | Short Beam Shear Strength for Composite Materials | ASTM D2344/D2344M |
| M-219C | Shear Stress-Strain for Composite Materials | ASTM D5379/D5379M |
| M-204C_45 | In-Plane Shear Stress-Strain, Strength and Modulus by Tensile test of a ±45° laminate | ASTM D3518/D3518M |
Shear Testing Specific to Elastomers
| Test ID | Test Description | Standards |
|---|---|---|
| M-220 | Planar Tension (Shear) | DPL M-220* |
* Internal DatapointLabs Standard
Principle of Operation
Shear testing methods vary depending on material type and test objective:
- Plate Twist Method (ISO 15310): Measures in-plane shear modulus by twisting a thin plate specimen and measuring angular deformation.
- Tensile Method (ASTM D412, ASTM D638, ISO 527-1): Calculates in-plane shear modulus indirectly from tensile moduli along different orientations (flow, cross-flow, and 45°) and Poisson’s ratio.
- Punch Shear Method (ASTM D732): Measures shear strength using a punch tool to force a circular section out of a material specimen.
- Short Beam Shear Method (ASTM D2344/D2344M, ISO 14130): Measures short-beam shear strength in composites using three-point bending.
- Iosipescu Shear Method (ASTM D5379/D5379M): Uses a double V-notched specimen loaded asymmetrically to induce a uniform shear stress field.
- Rail Shear Method (ASTM D7078/D7078M): Uses a rectangular specimen with bolted rails to apply pure shear loading.
- In-Plane Shear via ±45° Tensile Test (ASTM D3518/D3518M): Measures shear modulus and strength by tensile loading of a ±45° composite laminate.
Typical Procedure
- Specimen Preparation
- Shape and dimensions conform to the relevant standard.
- Specimen may require notching (Iosipescu), bolting (rail shear), or precise orientation (±45° laminate).
- Test Setup
- Specimen mounted in grips or fixtures appropriate to the test method.
- Strain measurement via extensometer or digital image correlation (DIC).
- Loading and Testing
- Load applied at a controlled displacement or force rate.
- Force and deformation continuously recorded.
- Post-Test Analysis
- Stress-strain curves generated.
- Key shear properties extracted.
Specimen Types
Specimens used by DatapointLabs in various types of shear testing are as follows:
| Specimen Type | DatapointLabs Test IDs |
|---|---|
| Plaques [Details] | M-017 |
| Plaques (4in x 12in) [Details] | M-013 |
| Discs (50mm Diam.) [Details] | M-038 |
| Shear Sample [Details] | M-219, M-219C |
| Assembled, Lap Bonded Specimens (1in x 10in) [Details] | M-041 |
| Thin Sheets or Film [Details] | M-220 |
| Contact Us [Details] | M-219RS, M-034C, M-204C_45 |
Extensometry Techniques
Extensometry techniques typically employed by DatapointLabs in various types of shear testing are as follows:
| Extensometry Technique | DatapointLabs Test IDs |
|---|---|
| Non-Contact Extensometry | M-219, M-219C, M-204C_45 |
| Determined from Tensile Values | M-013, M-220 |
| Crosshead Displacement | M-017, M-034C |
| Optical 2D Digital Image Correlation (DIC) | M-219RS |
| Not Relevant | M-038, M-041 |
Characterization Measurements (General)
Shear Modulus (ISO 15310, ASTM D412, ASTM D638, ISO 527-1, ASTM D5379, ASTM D7078/D7078M)
- Definition: Slope of the shear stress-strain curve in the linear region.
- Significance: Measures stiffness under shear loading.
Orthotropic In-Plane Shear Modulus (ASTM D412, ASTM D638, ISO 527-1)
- Definition: Derived from tensile moduli in flow, cross-flow, and 45° orientations and Poisson’s ratio.
- Significance: Critical for anisotropic materials like composites and filled polymers.
Shear Strength (ASTM D732, ASTM D5379, ASTM D7078/D7078M)
- Definition: Maximum shear stress sustained before failure.
- Significance: Indicates load-bearing capacity in shear-dominated applications.
Iosipescu Shear Stress-Strain (ASTM D5379) [Filled Plastics]
- Definition: Measurement derived from a double V-notched specimen.
- Significance: Used to induce a pure shear stress state in a uniform region.
- Measured Properties:
- Shear modulus
- Shear strain at yield
- Shear strength
- Shear strength at yield
- Offset yield stress
- Strain at offset yield
Shear Stress-Strain in the Rail Shear Method (ASTM D7078/D7078M-20e1)
- Definition: Measurement derived from a double V-notched specimen bolted between two rails and loaded in tension.
- Significance: Used to induce a pure shear stress state in a uniform region.
- Measured Properties:
- Shear modulus
- Shear strain at yield
- Shear strength at yield
- Shear stress vs. shear strain curves
- Failure type
- Load-displacement curve
Characterization Measurements (Composites)
Short Beam Shear Strength (ASTM D2344/D2344M, ISO 14130)
- Definition: Measurement derived from a short-beam three-point flexural test.
- Significance: Used to determine interlaminar strength of composites.
- Measured Properties:
- Short beam shear strength
Iosipescu Shear Stress-Strain (ASTM D5379/D5379M)
- Definition: Measurement derived from a double V-notched specimen.
- Significance: Used to induce a pure shear stress state in a uniform region.
- Measured Properties:
- Offset yield stress
- Shear modulus
- Shear strain at yield
- Shear strength
- Shear stress vs. shear strain curves
- Strain at offset yield
In-Plane Shear via ±45° Tensile Test (ASTM D3518/D3518M)
- Definition: Measurement derived from tensile loading of a ±45° composite laminate.
- Significance: Simplicity of fixturing and specimen preparation.
- Measured Properties:
- In-plane shear modulus G12
- Offset yield stress
- Shear strength
- Shear stress vs. shear strain curves
- Strain at offset yield
- Failure type
- Force-displacement curve
Typical Data Reported (see test descriptions for exact details)
- Shear Modulus: Relationship between stress and strain in the elastic region.
- Shear Strength and Strain at Yield: Stress and strain at the first deviation from linearity.
- Offset Shear Strength and Strain: An approximation of stress and strain at the material’s elastic limit.
- Shear Strength and Strain at Failure: Stress and strain at peak stress before failure.
- Shear Stress-Strain Curves: Plotted stress-strain relationship.
- Load-Displacement Curves: Applied load versus displacement.
Suitable Material Types
- Metals: ASTM D732 (punch shear).
- Plastics: ASTM D5379, ASTM D7078, ASTM D638, ISO 527-1.
- Elastomers: ASTM D412.
- Composites: ASTM D5379, ASTM D3518, ASTM D2344.
Suitable Applications
- Material Selection: Evaluating shear strength and resistance to sliding forces for layered materials such as composites, adhesives, or other materials.
- Component Design: Assessing performance of fasteners, rivets, and bonded joints under shear loads.
- Quality Control: Ensuring consistent shear properties in materials such as composites, polymers, and metals.
- Research & Development: Testing new materials and adhesive formulations for improved shear resistance.
- Failure Analysis: Identifying causes of material failure such as delamination, tearing, or shearing fractures.
- Product Certification: Verifying compliance with industry standards for shear strength and structural integrity.
- Process Optimization: Assessing the impact of manufacturing variables on shear performance in laminated and bonded materials.
- Environmental Testing: Evaluating shear strength under conditions such as temperature fluctuations, humidity, or chemical exposure.
Conclusion
Shear testing provides critical insights into shear stiffness, strength, and failure mechanisms for materials exposed to shear forces, guiding material selection, product design, and structural safety. By following standards like ISO 15310, ASTM D5379, ASTM D7078, and ASTM D2344, engineers can ensure accurate, repeatable results, supporting the development of high-performance materials for demanding applications.
