The article presents the generalization of constitutive equations for rate-sensitive plastic materials to general states of stress. The author discusses the dynamical yield conditions for elastic, visco-plastic materials and introduces new relaxation functions. The paper provides solutions to the relaxation equations for such materials. The original equations, derived by Hohenemser and Prager, are generalized by replacing a term with a function that depends on the yield function. This leads to new constitutive equations that account for the rate of plastic strain and the effect of strain rate on material behavior. The equations are shown to be equivalent to those of isotropic work-hardening materials in plasticity theory, but with the yield radius depending on strain rate rather than strain. The paper also discusses relaxation processes for visco-plastic materials. It introduces an $A$-process, where stress and strain are homogeneous, and a $B$-process, where the surface velocities vanish. The relaxation equations for $J_2$, the second invariant of the stress deviation, are derived and solved using iterative methods. The solutions are expressed as nonlinear Volterra integral equations. The article further generalizes the constitutive equations to include more complex yield functions, such as those involving the third invariant of the stress deviation. It considers special forms of the function $\Phi(F)$, including power-law and exponential functions, and derives corresponding constitutive equations. These equations are shown to be consistent with known strain rate laws, such as the Cowper-Symonds-Bodner law and Sokolovskii's law. The paper concludes with a discussion of the validity of the solutions and the importance of the Lipschitz condition in ensuring the convergence of the iterative methods used to solve the relaxation equations. The work provides a comprehensive framework for understanding the behavior of rate-sensitive plastic materials under dynamic loading conditions.The article presents the generalization of constitutive equations for rate-sensitive plastic materials to general states of stress. The author discusses the dynamical yield conditions for elastic, visco-plastic materials and introduces new relaxation functions. The paper provides solutions to the relaxation equations for such materials. The original equations, derived by Hohenemser and Prager, are generalized by replacing a term with a function that depends on the yield function. This leads to new constitutive equations that account for the rate of plastic strain and the effect of strain rate on material behavior. The equations are shown to be equivalent to those of isotropic work-hardening materials in plasticity theory, but with the yield radius depending on strain rate rather than strain. The paper also discusses relaxation processes for visco-plastic materials. It introduces an $A$-process, where stress and strain are homogeneous, and a $B$-process, where the surface velocities vanish. The relaxation equations for $J_2$, the second invariant of the stress deviation, are derived and solved using iterative methods. The solutions are expressed as nonlinear Volterra integral equations. The article further generalizes the constitutive equations to include more complex yield functions, such as those involving the third invariant of the stress deviation. It considers special forms of the function $\Phi(F)$, including power-law and exponential functions, and derives corresponding constitutive equations. These equations are shown to be consistent with known strain rate laws, such as the Cowper-Symonds-Bodner law and Sokolovskii's law. The paper concludes with a discussion of the validity of the solutions and the importance of the Lipschitz condition in ensuring the convergence of the iterative methods used to solve the relaxation equations. The work provides a comprehensive framework for understanding the behavior of rate-sensitive plastic materials under dynamic loading conditions.