MOHR DIAGRAM I. USES OF DIAGRAM: (MOHR) A. With known principal stresses we can find stress components acting on any inclined plane e.g., s1 = 5kb s 3 = 2kb stress with q = 47o with 2q = 94o B. From general state of stress we can find the magnitudes and directions of principal stresses ex: given     4.5 sxx 1.5 txy -1.5 tyx 1.5 syy II. CONVERSIONS: (h.w.) A. 1 dyne/cm2 = 10-9 kbars B. 1 dyne/cm2 = 14.503 X 10-6 pounds/in2 C. 1 dyne/cm2 = 10-10 gig. pa D. 1 lb/in2 = 6.895 X 105 kb III. TYPES OF STRESS: - (6) states A. Uniaxial stress - one direction / s 1 1. 2. Principal stresses s1> 0 s2 = s3 º 0 3. Mohr diagram 4. Stress ellipse - is a straight line B. Biaxial stress - 2 directions 1. 2. s1 > s2 > s3 = 0 3. 4. C. Triaxial stress - 3 directions 1. Real world 2. s1 > s2 > s3 not equal to 0 3. 4. Axis lengths not equal D. Hydrostatic (special) - 3 equal directions of stress 1. 2. s1 = s2 = s3 = s 3. 4. Axes length equal (sphere) a. What a submarine feels b. With rocks it is lithostatic pressure E. Pure shear - special biaxial 1. 2. s1 = -s3 neither = 0 but s2 = 0 3. 4. No stress ellipsoid due to (-) axis F. Axial stress - (most rock experiments done with this) 1. Two cases: a. b. s1 > s2 and s2 = s3 c. d. 2. Second case a. b. s1 = s2 > s3 c. d.