Stress Hypotheses Apparatus
(MT113)
- Learning how to generate the multi-axial loads on test samples made of ductile metals:
- steel, copper, brass, aluminium
- Demonstrating the Mohr’s circle of stresses and strains
- Demonstrating the Tresca yield criterion
- Studying The Rankine yield criterion
- Familiarization of the yield point
- Studying the normal stresses hypothesis.
- Studying the shear stresses hypothesis.
- Generating a various load moment
- pure bending moment
- pure twisting moment
- combined bending moment and twisting moment
- torsion moment
- Specimens
- Length: 49mm
- Clamping length: 11,5mm
- Specimen diameter in measuring cross- section: Ø 4mm
- Weights to place load on specimens
- 1x 2N (hanger), 1x 1N, 1x 2N, 1x 4N, 2x 8N
- Weights to compensate for the load and the loading plate
- 1x1N, 2x2N, 1x4N, 2x8N Lever arm: 100mm
- Deformation
- Measuring range: 0…10mm
- Stress Hypotheses Apparatus (MT113)
- Hard copy of User manual
- Digital content (BI01)
- Set of bending and torsion specimens, Al, Cu, St and CuZn.
Stress Hypotheses apparatus is a bench top unit designed to allows the verification of stress hypotheses in specimens of different materials. by applying loads in various directions to a test specimen point and measuring the deformations produced, permits the investigation and testing of stress theories. Transverse stresses are avoided and only normal and shear stresses are used. Weights are attached to the device on one side and the test specimen is to produce the strains, situated on the opposite side. These weights are balanced using a counterweight.
- The Stress Hypotheses apparatus allows the verification of stress hypotheses in specimens of different materials.
- The main hypotheses occur when the part is simultaneously subjected to several unequal simple stresses, superimposing their actions, highlighting the hypothesis of normal stresses, deformation hypothesis and shear stress hypotheses.
- The unit mainly includes:
- Dial gauge
- Balance weight
- Loading plate
- Test specimen in clamps
- Deflection roller and cable to compensate for the dead-load of the plate
- Weight
- These stress-creating weights are supported on a graduated plate placed on the specimen, which allows the weights to be fixed at 15° differences, adding also bending and torsional moments.
- The test specimens have an annular cross- section in their loaded zone and the ends are reinforced for support.
- Stress hypotheses are used in the science of material strength to calculate comparative stresses when uneven stressors are coupled.
- Utilizing material qualities, the following stress theories have been investigated and validated in practice:
- The shear stress theory is supported by the Rankine yield criterion, the von Mises yield criterion, and the Tresca yield criterion.
- The specimen is secured to the fixed frame by a clamp at one end.
- On the opposite end, a loading plate issecured to the specimen.
- On the outside of the plate, a weight is fastened.
- The applied weight and the dead-load of the plate are balanced out by a balance weight.
- Shear forces are therefore avoided, and only direct and shearing stress occur at a spot on the test specimen as a result.
- A graduation grid on the loading plate allows weights to be attached in 15° increments.
- This makes it possible to create both pure bending and twisting moments as well as coupled load moments.
- On the loading plate, measuring points are situated perpendicular to the weight to gauge deformation.
- This makes it possible to measure the deformation at the point of maximal deflection.