Revisiting Inflection Circle via Level Luffing Crane for Academic Revival

Abstract

AbstractRepeated reference to a limited number of named straight line mechanisms in academics has introduced an element of dullness in the potentially challenging domain of synthesis and application. Young and vibrant domains like Compliant Mechanisms are likely to revive the interest in the synthesis of rigid body mechanisms as the starting topologies. Level Luffing Cranes are identified and described as one of the not-to-miss large size example of an approximate straight line mechanism. Historically the concept of Inflection Circle is more than three centuries old. Existence of the special point (Ball’s point or Undulation point) on the Inflection Circle is known for around one and half century. Involved theoretical nature of such concepts of the Path Curvature Theory has resulted into the marked avoidance at the introduction level of the courses on mechanisms. This paper highlights the possible association between synthesis of these mechanisms and the concepts related to Inflection Circle. Only the easy to explain traits of Inflection Circle and the Ball’s point are highlighted and their possible application in the synthesis of the double rocker kind of approximate straight line mechanisms is discussed. Three cases comprising of textbook and real life field examples are explained. Apparent limitations and introduction of higher level concepts of the path curvature theory are also discussed in the end. KeywordsLevel luffingStraight line pathInflection circlePath curvature