Louis Cloutier

A network approach to operate agile manufacturing systems

Abstract This paper presents and illustrates a strategic framework for designing and operating agile networked manufacturing systems. This framework allows to collaboratively plan, control and manage day-to-day operations and contingencies in a dynamic environment. The first section summarizes the NetMan organizational and collaboration strategy. It consists of a dynamic business method to organize and operate manufacturing activities through the configuration, activation and operation of a distributed network of inter-dependent and responsible manufacturing centers. Next, the concepts underlying this strategic framework as well as the technical implications of such an approach, are illustrated, using a detailed case study inspired by a motorcoach industrial partner.

A general formulation for the calculation of the load sharing and transmission error under load of spiral bevel and hypoid gears

Abstract This paper presents the basis of a Loaded Tooth Contact Analysis (LTCA) program predicting the motion error of spiral bevel gear sets under load, and explores some of the influences of the unloaded motion error curve shape and amplitude over the kinematical behaviour under load. The effects of tooth composite deflection caused by bending and shearing, tooth contact deformation and initial profile separation due to profile mismatch are considered in the development. Due to the complex geometry of spiral bevel gear teeth, the tooth bending stiffness is calculated by finite elements. Classical Hertz theory is used to calculate the contact deformation. Numerical examples are presented to illustrate the behaviour of spiral bevel gear motion error under load as the unloaded motion error is modified. Results show that under general circumstances, low contact ratio spiral bevel gears with parabolic unloaded motion error may produce undesirable kinematics under load, while parabolic motion error high contact ratio spiral bevel gears are likely to produce acceptable kinematics under a larger load range. It is also shown that the governing factors, in loaded motion error, are the contact ratio, thus combined mesh stiffness, and the amplitude of unloaded motion error curve which is linked to load sharing between adjacent tooth pairs.

A commitment-oriented framework for networked manufacturing co-ordination

In the rapidly changing world of market place evolution and pressures, many authors have studied new organizational forms. Within these new trends, this paper deals particularly with network organizations. An approach is thus proposed to integrate the overall business organization and to co-ordinate the business processes involved in achieving the overall organization goals. In this study, integration is concerned with the implementation of collaborative information structures, enabling efficient operation management and control among heterogeneous business entities. Thus, based on the contract theory from economic science, philosophical work done on conventions and the multiagent systems paradigm, a commitment-oriented co-ordination framework for business integration is proposed. These concepts present a new comprehensive formalization of business collaboration within networked manufacturing, insofar as they concern the modelling of many kinds of business interactions, including collaborative contingencies management and collaboration performance measurement. In order to illustrate this approach, a multiagent prototype using the commitment-oriented approach is finally presented.

Express Model for Load Sharing and Stress Analysis in Helical Gears

The performance of a gear set is strongly influenced by the manufacturing and assembly quality. Therefore, detailed analyses at the design stage, where the effects of expected assembly and manufacturing errors can be simulated, are crucial. At an early design stage, when contact conditions are addressed, the widely used finite element method (FEM) may still result in unwanted computing time. The paper presents an Express model developed to serve as a fast design tool offering fine simulation and a high precision level. The model establishes load sharing, fillet stresses and pressure distribution along the contacting surfaces of meshing helical gear teeth. The calculations combine the finite strip method with a pseudo-three-dimensional (3D) model of the tooth base solved with finite differences to calculate tooth bending deflexion and fillet stresses. The accuracy of the procedure is demonstrated through 3D FEM models. A contact cell discretization completes the model. This very fast and accurate approach gives the contact pressure distributions resulting from the roll-slide motion of mating teeth. An analysis of a helical gear set in two different assembly positions reveals the effects of edge contact, and exhibits the influence of tooth stiffness reduction near tooth corners.

Helical Gears, Effects of Tooth Deviations and Tooth Modifications on Load Sharing and Fillet Stresses

Based on a few specific cases, this paper presents a comparative investigation of the effect of helix slope and form deviation tolerances as specified by grades 5 and 7 of the ANSI/AGMA ISO 1328-1 Standard for Cylindrical Gears. In addition, the consequences of longitudinal flank crowning and radial tip relief modifications are investigated, as applied on a misaligned helical gear set. For all simulations, the express model (Guilbault et al., 2005, ASME J. Mech. Des., 127(6), pp. 1161-1172) is employed. The bending deflection and fillet stresses are obtained from a combination of finite strip and finite difference meshes. The rolling-sliding motion of mating gear teeth is modeled with a cell discretization of the contact area, which offers fast and accurate results. Similar contact conditions arise from a helix slope deviation or a misalignment of the gear set: the first contact point is driven to a theoretical contact line endpoint. Such a condition produces a localized, and clearly impaired, contact area subject to overloading. Consequently, flank crowning and tip relief corrections must be carefully regarded in the design process. The presented results highlight that, if improperly combined, profile modifications can amplify the overloading condition.

Experimental and numerical investigation of the meshing cycle and contact ratio in spiral bevel gears

The load carrying capacity of spiral bevel gears is governed by the way load is distributed between meshing tooth pairs, which is highly dependent on the actual contact ratio as the gears mesh. Previous experimental studies have shown that the AGMA calculated contact ratio is substantially different from that found in practice, because of the shape and dimensions of the bearing pattern produced by the load transmitted between meshing gear teeth. Given the geometrical complexity of spiral bevel gear tooth profiles, a Tooth Contact Analysis computer program is used to determine the location of the path of contact, the dimensions of the bearing pattern under load and the associated contact ratio. The objectives of this paper are to experimentally and numerically study the relationships between the bearing pattern of selected spiral bevel gear sets and their load meshing cycles, to evaluate the actual contact ratio, and to calculate and compare the corresponding AGMA contact ratio to measurements and values calculated by a Loaded Tooth Contact Analysis computer program.

Strain Measurements on ACSR Conductors During Fatigue Tests I—Experimental Method and Data

Electrical transmission lines are subjected to aeolian vibrations which may lead to the failure of overhead conductors by fretting fatigue at suspension clamps. In order to obtain a better understanding of the damaging mechanism of these conductors, strain measurements have been taken on wires near critical sites. The strain gauges were glued in order to separate the bending and the traction strain modes, which gives major insights into conductor mechanics. While the static loading is a combination of traction and bending loadings, the alternating loading is mainly an alternating traction. Alternating stresses used as fatigue indicators do not correlate well with the experimental results due to crude assumptions.

An agent-driven approach to design factory information systems

Abstract This paper presents an agent-driven approach for the design of factory information systems. The approach exploits the object/agent-oriented paradigm to construct a factory information system by networking domain-dedicated responsible manufacturing planning and control software agents. The paper presents the agent-based perspective adopted, and then discusses the generic architecture of agent-based factory information systems. Two illustrative examples are provided, one based on the hierarchical manufacturing planning and control scheme behind the ISO/TC 184 AG N 19–20 reference model shop floor production control, and a second based on a distributed planning and control scheme derived from a commercial implementation by the authors, of an agent-based factory information system.

Fatigue strength characterization of ACSR electrical conductors at suspension clamps

A new system for testing the fatigue strength of ACSR electrical conductors at suspension clamps has been designed. Two benches based on this new design have been used to perform fatigue tests on two typical ACSR conductors. These tests have been planned to study the influence of bending amplitude, mean tensile load and clamping pressure. Recordings of the time sequence of the wire breaks have yielded a better definition of conductor fatigue up to 108 cycles on the endurance curves. Wire fracture location analysis has also yielded some new results on the bending behaviour of an ACSR-suspension clamp system.

Elastic-Plastic Microcontact Model for Elliptical Contact Areas and Its Application to a Treillis Point in Overhead Electrical Conductors

Aeolian vibrations represent a threat to the integrity of electrical transmission lines. The fretting fatigue of conductors is thus a major concern. The modelization of the contact conditions at critical points is an important tool in assessing the life of conductors. Treillis points around the last point of contact between the conductor and the pieces of equipment are such critical points. We observe a fully plastic contact condition at these points. Finite element results for the contact between an ellipsoid and a rigid plane and between two wires at different angles are compared with an elastic-plastic microcontact model for elliptical contact areas. These numerical results are then compared with experimental ones for the contact between two wires of a conductor (ACSR Bersfort), showing a very similar relationship between the contact force and the observed contact area. We have a good correlation between the microcontact model and the finite elements ones in the fully plastic contact regime on both the contact area and the contact force for a given interference between bodies. The use of the elastic-plastic microcontact model for elliptical contacts presented in this paper proves to be a strong tool in getting a better understaruling of the mechanical behavior at those critical points.