Load frames testing

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Load frames testing utilises a high stiffness support structure against which the test forces can react. The load frame comprises a base beam, two columns and a moving crosshead that when fitted with fixtures can measure different mechanical properties related to strength and displacement.

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Tension

Test name	Tension testing
Description	The most fundamental of type of mechanical test; provides information about how materials react to force being applied as it is pulled apart – as well as its strength and how much it will elongate
Fixtures	10kN Screw Side Action Grips 50kN Wedge Action Grips
Jaw faces	10kN Grips	Flat and serrated, Round and vee serrated
Jaw faces	50kN Grips	Flat and serrated, Round and serrated
Testing considerations	Cross-sectional area Specimen shape and dimensions
Test control	Preload, Precycle, up to two speeds
Calculations	Absolute peak Local peaks Preset points User Calculations	Modulus (nine types) Yield (five types) Break (six types) Slack/Compliance correction	Poisson’s ratio Area reduction Break location Seam Slippage
SOP	Load Frames Testing SOP (PDF, 94.2 KB)
Booking address	G SEBE ENG Lab Eqpmt KE2.101 Instron 10kN G SEBE ENG Lab Eqpmt KE2.101 Instron 50kN

Compression

Test name	Compression testing
Description	Provides information about how materials deform under crushing loads – as well as being useful for measuring the plastic flow behaviour and ductile fracture limits of materials.
Fixtures	Compression platens
Testing considerations	Cross-sectional area Specimen shape and dimensions
Test control	Preload, precycle, up to two speeds
Calculations	Absolute peak Local peaks Preset points User calculations	Modulus (nine types) Yield (five types) Break (six types) Slack/compliance correction	Poisson’s ratio Area reduction Break location Seam slippage
SOP	Load Frames Testing SOP (PDF, 94.2 KB)
Booking address	G SEBE ENG Lab Eqpmt KE2.101 Instron 10kN G SEBE ENG Lab Eqpmt KE2.101 Instron 50kN

Flexural

Test name	Flexural testing
Description	Provides information about how materials behave when subjected to simple beam loading, which produces tensile stress in the convex side of the specimen and compression stress in the concave side.
Fixtures	Lower Flexure and 3 Point Bend Upper Fixture 4 Point Bend Upper Anvil Fixture
Testing considerations	Cross-sectional area Specimen shape and dimensions Minimising shear stress in the specimen by controlling the span to depth ratio
Test control	Preload, tensile/compressive
Calculations	Absolute peak Local peaks Preset points User calculations	Modulus (nine types) Yield (five types) Break (six types) Slack/compliance correction	Poisson’s ratio Area reduction Break location Seam slippage
SOP	Load Frames Testing SOP (PDF, 94.2 KB)
Booking address	G SEBE ENG Lab Eqpmt KE2.101 Instron 10kN G SEBE ENG Lab Eqpmt KE2.101 Instron 50kN

COD Gauge

Mechanical property	Crack Open Displacement (COD) is suitable for both fatigue crack growth studies and fracture toughness measurements.
Principle of operation	The COD gauge gives a precise indication of the relative displacement of two accurately located knife-edges (or machined reference edges), which span the starter notch of the specimen.
Specifications	Gauge length 5mm, maximum travel 2mm.
Standards	Comply with requirements laid down in ASTM E399-09. Suitable for testing to determine the fracture toughness of metallic specimens as described in BS 7448, ASTM E399, ASTM E361, ASTM E1290, ASTM E1820, and ISO 12135, ISO 12737. Suitable for fatigue crack growth studies according to ASTM E647 and ISO 12108.
Testing considerations	Type of specimens Installation of the gauge See the testing considerations document (PDF, 259.5KB)
Calculations	Crack length K_IC, is calculated from the values of load versus crack opening displacement. The K_IC value characterises the resistance of the material to fracture in the presence of a sharp crack under static loads.
Resources	Crack Opening Displacement (COD) Gauge

Video Extensometer

Mechanical property	Extension displacement Strain displacement
Principle of operation	The AVE2 Video Extensometer measures accurate specimen strain during a materials test without contacting the specimen. There is no mechanical influence on the specimen and increased reproducibility. This is achieved through accurate detection of gauge length markers using a high resolution digital camera.
Specifications	Lens focal length = 9mm Axial field of view = 425 mm Transverse field of view = 57mm Minimum axial gauge length = 12mm Minimum transverse gauge width = 12 mm AVE2 resolution = 1.5mm AVE2 measurement accuracy (axial and transverse in mm) = the greater of ±3 or ±1% of reading
Testing considerations	Marking the gauge onto the specimen – colour, size and shape of gauge marks (PDF, 201.9KB) Use with Digital Image Correlation
Resources	Crack Opening Displacement (COD) Gauge

Bluehill3 Software

Description	Program used to develop methodology and run the tests. Tailored application solutions from the simplicity of a basic peak load test to the power required for a complex cyclic test.
Test method types	Tension Compression Creep/Relaxation	Flexural Peel/Tear/Friction Tension Test Profiler	Compression Test profiler Metals for EN/ISO Standards
Method development considerations	What is the test going to do? What starts and stops the test? What speed or speeds should the test run? What is the shape and dimensions of the test specimen? What data is collected and at what rate? What output (results tables, graphs, reports) are required? What answers from the test do you require? What information is going to be supplied by the operator?
Testing control	Determines how the crosshead moves during the test – ie: pull apart = tension, crush = compression, beam loading = flexural To specify a hold use either a Creep/Relaxation or Test Profiler method. To test metals to EN/ISO standards where up to three speeds or reversing direction for a hysteresis modulus use the Metals method. Preloading or Precycling can be done with Tension, Compression or Test Profiler methods. For complex method design involving up to 87 segments of ramps, holds or cycles with calculations applied to each segment use the Test Profiler method.
Testing control	End of Test Criteria Rate of Load Sensitivity (%): The test ends when the load drops by the sensitivity value within a 100ms time period. The sensitivity is measured as a percentage of the load at the beginning of the 100ms period Load Threshold Load drops to: The test ends when the load falls to the Load drops to value. The load must first attain a value 1.5X the load drops to value before the detector becomes active Load with Delay The detector is inactive for the delay period that you specify. After this time has elapsed, the test ends when the load falls to the Load drops to value % Peak Load The detector is inactive until the load specified in the load threshold field has been exceeded. After that value is attained, the tests ends when the detector finds the specified load drop by (%) from peak load Measurement Event Value: The transition occurs when the system detects that the specified measurement criteria are satisfied. The parameters for this event requires a measurement and specified value criteria Digital Input Event The transition occurs when the system receives a signal from an external device through the specified digital input line. This event requires a specified digital input line. Set the digital input condition for the specified input line in the Load Frame Settings area of the console PIP Count Value: The test ends when the system detects the specified number of PIP marks
Defining the console	Live Displays Appear in the margin at the top of the screen Up to 4 options can be displayed Let you monitor data on selected measurements, or monitor real time results, during a test Soft Keys Programs functions that can be used through the software or on the control panel Buttons on the control panel relate to each live display (ie: 1 = first button etc) Frame Set the test area to …….. for tensile tests, and below the crosshead for compression and flexural tests Specimen Protect feature is available here Specimen Protect protects the specimen from too much load being applied when it is installed – set the threshold value at the maximum load that the specimen can experience without damage Valid specimen protection values include: Minimum 0.1% of full-scale load or 10N, whichever is greater Maximum full-scale load Default 0.5% of full-scale load
Measurements	Extension - Acquired from Crosshead travel Load - Acquired from the Load Cell Time - Acquired from Bluehill controller Strain 1 - Calculated from Extensometer connected to Strain 1 board (eg: AVE2 non-contacting or contacting strain gauge) Strain 2 - Calculated from Extensometer connected to Strain 2 board Video strain - Acquired from Extensometer connected to Video board Tensile Strain - Calculated from Extension or Strain1/2 and is configured with the measurements area of the method Tensile Extension - Calculated from Tensile Strain % Strain - Calculated as Value/Gauge Length: Uses the Extensometer Gauge Length if source comes from extensometer Uses Specimen’s Gauge Length dimension if source comes from extension Physical - Data read directly from the transducer connected to the testing system. Virtual - Data calculated from a mathematical expression using data from one or more physical measurements: Compressive Extension - Compressive strain multiplied by the anvil height Compressive Load - Standard load with the sign inverted Compressive Strain - Can change the source of its information during a test eg: from extensometer to crosshead Flexure Extension - Flexure strain multiplied by an outer fiber strain factor Flexure Load - Standard load with the sign inverted Flexure Strain - Can change the source of its information during a test Flexure Stress - Flexure Load divided by an outer fiber stress factor Load/Width - Dividing all the readings of the load measurement by the width of the specimen Peel Extension - Extension divided by a peel factor. The value of the peel factor varies according to the specimen geometry. For 90° peel specimens and friction specimens, the peel factor is 1. For 180° peel specimens, T-peel specimens and tear specimens, the peel factor is 2. Tenacity - Load divided by linear density Tensile Extension - Tensile strain multiplied by the specimen gauge length Tensile Strain - Can change the source of its information during a test Tensile Stress - Load divided by the cross-sectional area of the specimen Corrected Extension - Corrects values of extension to allow for the compliance, or elastic “give”, of the testing system. The compliance is determined by performing a test using a dummy specimen that deforms very little at the maximum test load. Important to use exact same test set-up as actual samples when creating compliance file Creating an Expression - Using the expression builder you can create formulas to calculate virtual measurements, custom calculations and logical expressions. The formula must be comprised of predefined values and follow standard algebraic rules
Data collection rate	Recommended 100 – 1500 points Maximum 1000 points/sec
Calculations	By using the Domain, the area or portion of the data the software analysed to calculate the results can be set.
Calculations	Absolute peak Local peaks Preset points User calculations	Modulus (nine types) Yield (five types) Break (six types) Slack/compliance correction	Poisson’s ratio Area reduction Break location Seam slippage
Exports	There are 3 – 4 different types of export files that each need to be enabled to export Report – a document that you can customise to include graphs, results tables etc. The file format can also be chosen. Results – exported as a .CSV file, must be enabled to be exported. Additional information can be selected to be included in the file above the results. Raw data – exported as a .CSV file, must be enabled to be exported. Additional information can be selected to be included in the file above the results. Defaults Table – Only appears in the report and not displayed anywhere in the software. The table can be customised of names and values of any parameters in the testing system. Can be used to display information/parameters that do not change between specimens and that relates to the entire sample, so that a column isn’t produced in the results table with the same value.
Test prompts	Two different types: Freeform test – the only prompts are those you can add to the operator inputs area of the test workplace Prompted test – choose the number steps in the test sequence that can be customised to enter certain parameters at certain points.
SOP	Load Frames Testing SOP (PDF, 94.2 KB)
Resources	Knowledge on BlueHill3 TrendTracker – compiles results and analyses trends.