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Material Testing Equipment
A custom-built testing machine developed to apply controlled tensile loading and continuously record force and displacement during material testing.
Type
Custom Testing Machine
Testing
Tensile
Motion
Stepper Motor
Lead Screw
Measurement
Force
Displacement
Standard
ASTM D638
01
The testing apparatus was developed as a small-scale universal testing device for controlled and repeatable material testing.
Tensile testing required a system capable of applying controlled linear force to specimens while continuously measuring their response. The machine was developed specifically to provide this testing framework within the constraints of the research.
The resulting apparatus combines controlled linear motion, specimen gripping, force measurement, and displacement tracking into a single testing system.
02
A stepper motor-driven lead screw converts controlled rotational movement into precise vertical displacement.
The lead screw forms the basis of the machine's movement system. As the stepper motor rotates, the moving assembly translates vertically through a known displacement.
Controlling this movement allows consistent loading rates to be maintained throughout each tensile test and provides a repeatable relationship between motor movement and specimen displacement.
03
Samples are mounted between two grips, creating a direct loading path through the specimen.
One grip remains fixed while the second is connected to the moving assembly. As the motor advances, separation between the grips increases and places the specimen under tension.
Testing continues as the tensile force increases until the specimen reaches failure, allowing its response throughout the loading process to be recorded.
04
An integrated load cell records the force generated as the specimen is placed under tension.
Force data is captured continuously during the test rather than only at the point of failure. This makes it possible to observe how the material responds as load increases.
The force measurements are recorded alongside the position of the moving assembly, creating a continuous record of specimen behaviour throughout each test.
05
Specimen displacement is derived from the controlled motion of the stepper motor and lead screw.
The lead screw pitch and stepper motor resolution provide a known relationship between commanded motor movement and linear travel of the gantry.
This allows displacement to be tracked throughout testing without requiring a separate displacement sensor in the testing setup described in the research.
06
Force and displacement were independently checked against known reference measurements before material testing.
The load cell was verified using calibrated weights, establishing a relationship between sensor output and the applied force.
Displacement calculated from lead screw pitch and stepper resolution was checked using caliper measurements at known positions along the gantry. This confirmed that commanded movement corresponded to actual linear displacement.
07
After each test cycle, the gantry returns to a home position to establish a consistent starting condition.
Returning to the same reference position resets the system between specimens and supports repeatable displacement measurements across a larger testing series.
The apparatus is not intended to replicate an industrial universal testing machine. Instead, calibration and repeatable positioning provide consistent comparative measurements within the scope of the research.
08
Tensile testing used ASTM D638 dog-bone specimens to establish a consistent geometry and testing procedure.
ASTM D638 uses a reduced central gauge section to promote controlled stress distribution and encourage failure away from the grips. Samples were mounted in the machine and loaded in tension at a constant rate until failure.
Force and displacement were recorded continuously during each test, providing the measurements used to evaluate tensile strength, elongation at break, and stiffness.
09
The machine provided a repeatable framework for comparing the mechanical behaviour of lignin-based material specimens.
Standardized specimen geometry, controlled loading, continuous force measurement, and calculated displacement allowed material tests to be compared using the same experimental setup.
The apparatus supported the larger investigation into how the material developed strength and responded mechanically under controlled tensile loading.
Main Research Project