Flexible Material Testing and Characterizing by Adding Precise Measurements

The choice of material plays a vital role across many industries, as manufacturers seek to reduce weight and cost of vehicles, machines, constructions and devices or consumer good in general.

As part of the structural integrity domain, the mechanical characteristics of new material components, such as metal, alloy, concrete, polymers, ceramic, moulded structural plastics or advanced composites, are essential to achieving optimal safety, durability, flexibility, strength-to-weight ratio, performance, reliability and cost-effectiveness.

Scientists and engineers in product design, simulation and testing rely on material properties such as stress, strain, tensile modulus, and Poisson’s ratio. Accurate material property data prevents failures in the field and anticipatex issues before they arise.

Thus, material properties testing is a critical step in understanding how your material will perform under a wide variety of stresses. It is commonly performed by testing machines, that meet the many ISO and ASTM standards. However, adding additional sensors is highly recommended as it helps to get an even better and more precise understanding of structural characteristics.

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What is Material Properties or Coupon Testing?

Material testing breaks down into five major categories, finding the properties or characteristics in the fields of mechanical, thermal, electrical, corrosion, radiation, and biological deterioration.

The mechanical testing methods can be divided into destructive and non-destructive material testing:

Destructive Testing: Random samples are loaded so heavily that they are destroyed. This serves to determine the maximum load and the behaviour under the influence of this load.
Non-destructive Testing: Workpieces of the material are tested without destroying them.

A further classification of the test procedures is based on the type of load:

Static Testing: Loads (tensile, compressive, or bending loads) act very slowly or constantly on a material sample.
Dynamic Testing: The sample is subjected to an abrupt load or a load acting periodically over a longer period.
Cyclic Testing: The sample is subjected to recurring, swelling or alternating load cycles in, for example, sinusoidal form.
Impact Testing: The sample is subjected to an impact like as in a Charpy test.

In a tensile test, the test coupon is pulled to its breaking point. Based on the material characteristics you get a true understanding of the material´s behaviour, how much energy it may absorb allowing you to predict the performance of the product in its real-life application. Some tests may also need to be performed in environmental chambers.

Destructive Material Testing (click to enlarge)

Reliable Results: Adding HBK Measurement Equipment

In material testing, highly accurate sensor data helps to get a better and more precise picture of material properties and gives you the extra plus of getting deeper test data. Integrating QuantumX allows overlaying additional sensor data sources and delivers precise and reliable results.

The integration of an HBK measurement chain into material testing systems such as MTS, Instron or ZwickRoell is easy. You can directly integrate the unit:

In real-time via EtherCAT, PROFINET or voltage inputs
Via PC software integration, measuring with catman Easy in parallel fusing data file
Directly into the test machine software via simple API commands

Parallel installation enables you to also get sensor data while the material testing machine is running. Measurements on various places on the coupon and on any material are possible. You receive precise data about the material´s behaviour according to loads, strain, temperature and whatever you want to measure.

Want to see an example? Zwick Roell integrated QuantumX and catman into their testing system. Read more

HBK solution for tests up to 200 kS/s
HBK solution for tests from 200 kS/s to 2 MS/s

catman

Easily acquire, visualize, and analyse your measurement data and store in all common file formats – online or post-process. catman can also integrate the FOM Aramis.

QuantumX

Universal DAQ system, popular for its low noise, precise inputs, its versatility and ease of use. Maximum resolution is needed, when capturing the relatively small elastic regions.

Typical sensors to be used:

Electrical or optical strain gages whenever highly accurate data is needed
Pt100 for temperature measurement and sensing compensation in environmental climate chambers
Extensometers
Camera-based stereoscopic deformations using triangulation, whenever rough 3D displacements surface strain and graphical pictures are needed

Typical modules in use:

MX840B universal amplifier supporting up to 17 different sensor types
MX410B universal high-speed amplifier for measurements up to 200 kS/s per channel

Perception

Easily acquire ultra-fast data from Genesis Highspeed systems and analyse these with user defined formulas. Calculations like dynamic Young’s modulus or rosette strain can be done and automatic reports per sample can be created. Cross sample report tables spanning test series with hundreds of coupons are possible as well.

Genesis HighSpeed

Modular, universal DAQ system, used for high sample rates up to 2 MS/s typically needed to test stiff or composite materials.
Available with Sigma-Delta ADCs for maximum resolution or SAR ADCs for minimized overshoot measuring fast rising signals in destructive material testing like Charpy pendulum or Hopkinson bar tests.

Typical sensors to be used:

Electrical strain gages in 1/1, ½ or ¼ configuration
IEPE type Accelerometers
Charge type sensors
DC supplied sensors like Kulite pressure transducers for fast pressure waves
Thermocouples or Ptxx for temperature measurement
Ultra-High-Speed cameras with thousands of frames/s

Typical input cards in a Genesis Highspeed system:

GN840B / GN1640B universal input card with 500 kS/s @ 24 bit supporting most common sensors
GN815 / GN816 high speed input card with 2 MS/s and SAR ADC for accelerometers for ultra-fast rising signals

HBK also offers material testing as a service, delivering fully characterized and interpreted material parameters ready for us in mechanical FAE or CAE-based fatigue analysis using nCodeDesignLife.

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Calibration

When a material testing machine is calibrated, reference points of the measurement device are compared to a reference sensor calibrated to a known traceable standard laboratory. Many material test machine manufacturers around the world calibrate their sensors and machines in production and in service with the HBK reference measurement chain.

DMP41 and MGCplus have a strong place in laboratories worldwide including the PTB, NIST and other metrological institutes. The QuantumX MX238B is the perfect portable tool for calibration services at customer sites. All HBK devices can be traced back to DAkkS by our accredited lab in Darmstadt, Germany, guaranteeing that your calibration services are performed precisely and efficiently, with traceable results. Whether they are static or dynamic materials testing machines, HBK provides the perfect measurement solution.

Through mutual recognition of national accreditation bodies, we ensure worldwide validity of your calibration certificate and measurement results. The calibration procedures are determined by internationally recognized standards.

Calibrating the instrument itself can also be done. This ultimately certifies the overall accuracy and determines traceability of the measurements. Internationally recognized standards have been developed for calibration of crosshead speed and displacement (ASTM E2658 and E2309), strain and load rate (ASTM E2309), and measurement of tension, compression (ASTM E4), torque (ASTM E2624), and dynamic force (ASTM E467).

All in all, HBK offers the right tool set enabling a variety of calibration and maintenance services in a highly efficient and traceable way.