In a biaxial state of stress, with normal stresses of n/mm² and n/mm², and a shear stress of n/mm², we can calculate the maximum principal stress using the formula:
Maximum Principal Stress = (σ1 + σ2) / 2 + √((σ1 - σ2) / 2)² + τ²)
Where σ1 and σ2 are the normal stresses, and τ is the shear stress.
Plugging in the given values:
Maximum Principal Stress = (n/mm² + n/mm²) / 2 + √((n/mm² - n/mm²) / 2)² + (n/mm²)²
Simplifying the expression:
Maximum Principal Stress = 2n/mm² / 2 + √(0) + n²/mm²
Maximum Principal Stress = n/mm² + n²/mm²
Therefore, the maximum principal stress in this biaxial state of stress is n/mm² + n²/mm².