1.1 Kinematic Analysis
Once a tentative mechanism design has been synthesized, it must then be analyzed. A principal goal of kinematic analysis is to determine the accelerations of all the moving parts in the assembly. Dynamic forces are proportional to acceleration, from Newton's second law. We need to know the dynamic forces in order to calculate the stresses in the components. The design engineer must ensure that the proposed mechanism or machine will not fail under its operating conditions. Thus the stresses in the materials must be kept well below allowable levels. To calculate the stresses, we need to know the static and dynamic forces on the parts. To calculate the dynamic forces, we need to know the accelerations. In…show more content… This approach offers some advantages in the synthesis of linkages. The links are represented as position vectors. Figure 1.2 shows the four bar linkage as in but the links are drawn as position vectors which form a vector loop. This loop closes on itself making the sum of the vectors around the loop zero. The lengths of the vectors are the link lengths which are known. The Current linkage Position is defined by the Input angle θ2 as it is a one DOF Mechanism. We want to solve for the unknown angles θ3 and θ4. To do so we need a convenient notation to represent the…show more content… Relative position of any link or a point on a link with respect to a reference frame which may be attached to a moving link or the fixed link;
2. The path traced by a point on a link in plane which is attached to a moving link or the fixed link;
3. The angular or linear displacement of a link or a point on a link relative to the fixed link.
From the definition of the degree-freedom of a mechanism, in order to determine the position of each link, the number of independent parameters to be defined must be equal to the degree-of-freedom of the mechanism. The joint parameters will define the relative position of two links connected by a joint. The joint whose parameter is defined will be called the input joint. However, if one of the links connected by the joint is fixed, the word input link may also be used since the joint parameter defines the absolute position of the other link.
1.2.3 Velocity Analysis of Mechanisms:
The standard approach to velocity analysis of a mechanism is to take derivative of the position equations with respect to time. (Note, alternative approaches, such as those termed influence coefficients, can be performed by first taking the partial derivative with respect to an alternate parameter multiplied by the time derivative of that