1.摩擦角的概念如图1所示,当物体静止且有摩擦时,支承面对平衡物体的约束力包含法向约束力F_N(即支持力)和切向约束力f(即静摩擦力),这两个力的合力F_R称为支承面的全约束力,它的作用线与接触面的公法线成一偏角ψ。当物体处于平衡的临界状态时,静摩擦力为最大静摩擦力,偏角ψ也达到最大值,如图2所示。全约束力与法线间夹角的最大值ψ_0称为摩擦角,由图可知tanψ_0=(f_(max))/(F_N)=μ_s,即摩擦 1. The concept of friction angle As shown in Figure 1, when the object is stationary and frictional, the restraining force of the bearing surface against the balancing object includes the normal binding force F_N (ie supporting force) and the tangential binding force f (ie static friction force) The resultant force F_R of these two forces is called the full binding force of the bearing surface, and its action line is at an angle ψ to the normal line of the contact surface. When the object is at a critical equilibrium state, the static friction is the maximum static friction and the declination angle ψ reaches the maximum, as shown in Fig. 2. Full binding force and the normal angle between the maximum ψ_0 known as the friction angle, the figure shows tanψ_0 = (f_ (max)) / (F_N) = μ_s, that is, friction