Axial tensile stress

In order to test the strength of a ceramic, cylindrical specimens of length 25 mm and diameter 5 mm are put into axial tension. The tensile stress a which causes 50% of the specimens to break is 120 MPa. Cylindrical ceramic components of length 50 mm and diameter 11 mm are required to withstand an axial tensile stress with a survival probability of 99%. Given that m = 5, use eqn. (18.9) to determine oh... 

Figure 6-6. Maximum axial tensile stress in the coating as a function of coating thickness for SiC coatings on Amoco T-50 carbon fiber.

Seismic forces have effects somewhat similar to wind loads in that the vertical tower is loaded as a cantilever beam standing on end and fixed at the base. There is a difference in the distribution of wind loads compared to seismic loads, but in both instances the vertical column is exposed to bending which produces axial tensile stresses on one side and axial compressive stresses on the other side. These must be combined with the axial stresses from the operating pressures for both vacuum and pressure operation. 

For the lower portion of tall towers, where the combined axial stress controls the design of the shell, there is the problem of selecting the maximum allowable axial compressive stress. The combined axial tensile stress presents no problem. The tensile stresses produced by internal pressure, bending stress of wind loads or bending stress firom seismic loads may be combined by simple addition of the stresses. The thickness of the shell may be calculated so that the combination of axial tensile stresses is equal or less than the maximum permissible value specified by the ASME Code. 

For unidirectional fibre composites with each of the following compositions, predict the strengths and describe the failure processes under axial tensile stress. 

Hollow microspheres imbedded in matrix can be subjected to compressive stresses locally prior to cracking as will be shown later. When the tri-axial tensile stress (cr ) created internally due to an external load is applied to such a hollow microsphere that is already under compressive residual stress (cr ) in the vicinity of the crack tip, there will be a transition between the two stress components. In this situation, the following two different cases, depending on the magnitudes of stresses around the microsphere, can be considered Case I ... 

A vertical, cyUndricaJ rod of a (very) viscous fluid with a constant exten-sional viscosity jje has an initial length lo- An axial tensile stress cth is applied to one end of the rod, while the other end is held fixed. Obtain an expression for the extension ratio a = l/lo as a function of time. Neglect the effects of gravity on the rod material. Hint. The local tensile strain in the material is dsu = dl/l. Consider two cases ... 

Aveston etai [50] developed a model which considered the sum of the bending stress and the axial tensile stress at the point at which the fibre intersects the crack surface. They calculated the ratio between this total local stress and the axial stress that can be supported by the fibre, as presented graphically in... 

The Pin and Ft were set constant at design conditions, which are 22 MPa and 1785 kN, respectively. The response for the riser is then obtained by applying a range of M, on the riser. Under combined Pin, Ft, and M, loads, the axial strain is found to be the dominant mode of failure, arising due to the positive axial tensile stress contributed by both... 

Constant tensile load joint tests (CTLJT) are conducted to meet the requirements of ASTM F 1924 section 6.2.4. Due to the viscoelastic properties of plastics, some mechanical fittings produce joints that pass the quick tensile test at 0.2 in/min., but fail a CTLJT. This test was designed to identify those fittings so that they could be redesigned or removed from consideration by the utility. The CTLJT is performed on in-line joints only. One specimen of each nominal pipe size is tested using method ASTM F 1588. The joint is subjected to internal pressure and external loading to provide an axial tensile stress of 1320 psi for 1000 hours. Six in-line fittings have passed the CTLJT. 

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