Determination Of Cable Forces Research Articles

Tension prediction for straight cables based on effective vibration length with a two-frequency approach

Cost-efficient and theoretically simple vibration-based analyses are widely used to assess the axial forces of tensioned members. In the determination of cable forces, the applicability of an explicit-type formula depends on the suitability of the adopted theories and the accuracy of the known parameters. For straight cables, the sectional rigidity is generally assumed to be a known quantity and the end conditions are presumptive. Nevertheless, given data of these parameters could be vague or unreliable. Methodologies which omit the requirement of a priori data are thus preferable in practice.This paper illustrates an effective methodology for the tension prediction of cables with presumptive end conditions by making use of multiple measured mode frequencies. Simple yet accurate formulas are obtained from the exact expressions based on the Bernoulli beam theory. Due to the fact that this approach does not require the knowledge of the flexural rigidity of the testing cable and it can be performed using only a single sensor, the method is suitable to be implemented in a quick diagnosis scheme. Present research emphasizes developing an analytic basis to effectively correlate the proposed formulas with the concept of the effective vibration lengths. This concept has been widely recognized as a useful idea to interpret the dynamics of cable vibrations.

Determination of cable forces in cable‐stayed bridges constructed under parametric uncertainty

PurposeThe existing methods for determining cable forces in cable‐stayed bridges constructed are based on assumption of complete determinacy of structural parameters. This is usually referred to as deterministic analysis. But in reality there are uncertainties in design variables. These uncertainties include geometric properties (cross‐sectional properties and dimensions), material mechanical properties (modulus and strength, etc), load magnitude and distribution, etc. Thus deterministic analysis cannot provide complete information regarding cable forces in cable‐stayed bridges constructed. The purpose of this paper is to determine cable forces in cable‐stayed bridges constructed under parametric uncertainty.Design/methodology/approachAn efficient and accurate algorithm is proposed to determine the cable forces in cable‐stayed bridges constructed under parameter uncertainty. The proposed method is a hybrid method, consisting of the improved Monte Carlo simulation method and forward process analysis method.FindingsThe proposed algorithm can obtain more information about the cable forces at different construction stages than the commonly used deterministic method, and it provides an improved understanding of the cable forces in cable‐stayed bridges constructed with parameter uncertainties.Originality/valueThe values of this type of research are that: it developed an efficient and accurate algorithm for determining the cable forces in cable‐stayed bridges constructed under parameter uncertainty; and it provided an improved understanding of the cable forces in cable‐stayed bridges constructed with parameter uncertainties.

Optimization of a planar tendon-driven parallel manipulator for a maximal dextrous workspace

In this article, new methodologies for determining the tension distribution and optimal configurations of planar tendon-driven parallel manipulators (TDPMs) are presented. TDPMs are characterized by the use of cables in place of the linear actuators used in most parallel manipulators. Three separate, but inter-related topics are examined in this article, and methodologies for addressing them are proposed. The first is the determination of cable forces for overconstrained tendon-driven manipulators, which is necessary in order to address the second topic, namely, the development of a methodology for workspace determination of tendon-driven manipulators. The final topic examined is the dimensional synthesis of tendon-driven manipulators for a large dextrous workspace. The numerical methodologies developed here have potential for easy application to more complex spatial cases.