CC(T) Specimen Load-Bearing Capacity Related to Yield Strength and Upper-Shelf Charpy-V Energy

The load-bearing capacity of a CC(T) specimen (Center-Cracked Tension) in the ductile fracture regime is usually controlled by plastic collapse. If the material’s tearing resistance is sufficiently low, the load-bearing capacity can drop below the plastic collapse value. Here, a recently developed simple fracture mechanics-based Charpy-V impact energy criterion for plastic collapse was used to provide a best estimate assessment of the CC(T) specimen load-bearing capacity.

Variations in Testing Procedures on the Rotary Flexometer

The rotary flexometer described in German Standard Proposal DIN 53 533 has been used to determine heat generation and fatigue resistance on homogeneous rubber specimens, laminated specimens, and some containing fabric plies. When a series of compounds having a range of hysteresis or hardness is run at constant deformation amplitude, the ranking is usually inverse to that obtained when run at constant force amplitude. The test method should be chosen to correspond to the proposed use of the compound. Accessories developed permit testing of 10 ×. 10 mm cylindrical specimens as well as conventional 20 × 20 mm cylinders. Temperature measurements in the specimen center have proven to be more precise than those on the free surface or on a clamped surface. Temperature increase during cycling is strictly a function of the viscoelastic properties of the compound. Creep measured at ambient temperature may rate a series of compounds differently than if measured at an elevated temperature. Fatigue resistance is well represented by S-N curves where the logarithm of N, the cycles to failure is plotted as a function of S, the severity factor (deformation amplitude or force amplitude). An inverse relationship exists between rate of heat generation and failure by degradation of the specimen center. The vulcanization system affects fatigue life. The temperature reached during testing of a highly hysteretic material can be minimized by using it as the central layer of a laminated specimen and higher hysteretic materials for the rest of the specimen. The apparatus can be used for testing dynamic adhesion fatigue of rubber-fabric bonds. Failure between plies started as a failure of the bond between rubber and cord.