Introduction to Contact Mechanics Part 12 pot

... flow, 27 fracture surface energy, 33, 36, 117, 122 , 123 , 128 , 129 , 130 fracture toughness, 143, 144 friction, 110 frictionless contact, 77, 102, 125 , 153, 165 bonded interface, 202, 203 ... GPa 0.02 0.57 R 0.04 1.14 R 1.59 Contact 0.06 1.71 1.19 Contact Suggested # Actual diameter 0.08 2.28 R Suggested # Actual diameter 116 0.10 2.85 0.79 Contact 127 227 0 .12 3.4...

Ngày tải lên: 11/08/2014, 09:20

... geometry factor, and c is the crack half-length. K 1 is called the “stress intensity factor.” There is an impor- tant reason for the stress intensity factor to be defined in this way. For a particu- lar ... the strength of a particular structure was not appreciated by engineers. These failures led to the emergence of the field of “fracture mechanics. ” Fracture mechanics attempts...

Ngày tải lên: 11/08/2014, 09:20

... the two- dimensional elastic contact problems with friction,” Int. J. Numer. Methods Eng. 17, 1981, pp. 125 7 127 1. pp. 129 –137. A.C. Fischer-Cripps, “The Hertzian contact surface,” J. Mater. ... 7.6b apply equally well to the tip of a single- ended crack and thus are appropriate for the present analysis * . Second, although it is customary to apply a +12% correction to the...

Ngày tải lên: 11/08/2014, 09:20

... mean contact pressure and a is the radius of circle of contact) . Substituting this value of B into Eqs. 8.2.1a to 8.2.1d and normalizing to mean contact pressure p and radius of circle of contact ... the factor ( c 2 −b 2 ) −1/2 . Larger values of c cause the integral to evaluate to a lower value compared to smaller flaws at the same r o . From Eq. 7.6g, P c /a 3/2 is p...

Ngày tải lên: 11/08/2014, 09:20

... where the contact pressure for the elastic-plastic case, appears to be more uniformly distributed (except for the rise in contact pressure near the edge of the contact circle) compared to the ... these reasons, it is desirable to be able to measure fracture tough- ness using crack length data available from indentation tests. Attention is usually given to the length of the...

Ngày tải lên: 11/08/2014, 09:20

... available as bond potential energy (neglecting any dissipative losses due to heat, sound, etc.). The resulting two separated atoms have the potential to form bonds with other atoms. The atoms, now ... directions on a particular atom, and the atom takes up an equi- librium position within the material. Now consider an atom “B” on the surface. Such an atom is attracted by the many atoms j...

Ngày tải lên: 11/08/2014, 09:20

... is: () 12 1 12 π + ⎛⎞ = ⎜⎟ − ⎝⎠ A A F cb K cb c (2.5.2a) Forces F B also contribute to the stress field at A, and the stress intensity fac- tor due to those forces is: () 12 1 12 π − ⎛⎞ = ⎜⎟ + ⎝⎠ B B F cb K cb c ... to the additive nature of stress intensity factors, the total stress intensity factor at crack tip A shown in Fig. 2.5.2c due to forces F A and F B , whe...

Ngày tải lên: 11/08/2014, 09:20

... attribut- ing a quadratic function to represent the profile of the two opposing surfaces and gave particular attention to the case of contacting spheres. Condition 4 above, taken together with the quadric ... τ max , (e) the hydrostatic stress σ H , (f) σ 1 and σ 3 trajectories, (g) τ max trajectories. Fig. 5.3.2 Stress trajectories and contours of equal stress in MPa for Boussines...

Ngày tải lên: 11/08/2014, 09:20

... hence identical mean contact pressures), it is evident that more Now, for a given value of load P leading to equivalent contact areas of energy is required to obtain this contact pressure for ... size of the plastic zone is large in comparison to the size of the radius of circle of contact, then one may consider the mean contact pressure to be independent of the shape of...

Ngày tải lên: 11/08/2014, 09:20