ICES2008-1675 ADDRESSING CAM WEAR AND FOLLOWER JUMP IN SINGLE-DWELL CAM-FOLLOWER SYSTEMS WITH AN ADJUSTABLE MODIFIED TRAPEZOIDAL ACCELERATION CAM PROFILE

ABSTRACT Presented is a modified trapezoidal cam profile with adjustable forward and backward acceleration. The profile is suitable for single-dwell cam and follower applications. The main benefit of the profile is that it allows cam designers to choose easily a value for the maximum forward or maximum backward acceleration to achieve design objectives. An additional benefit of the profile is that it has a continuous jerk curve. Follower acceleration is one of the primary factors affecting cam wear and follower jump, two main concerns of cam designers. Large forward acceleration against a load creates cam-follower interface forces that can cause excessive wear. Backward acceleration tends to reduce the cam-follower interface force, and if the backward acceleration is sufficiently large, separation between the cam and follower ("follower jump") can occur. The cam profile presented in this paper gives cam designers an easy way to adjust the maximum forward or backward acceleration to prevent these problems

Stresses in Laminated Glass Subject to Low Velocity Impact

Finite element analysis is used to study small, low velocity missile impact of laminated architectural glass. The impact situation models that commonly observed during severe windstorms in which small, hard missiles impact laminated glass windows in large buildings. Architectural laminated glass is typically made of two soda-lime glass plies separated by a clear, sticky, polyvinyl butyral (PVB) interlayer. In order to increase the damage tolerance of laminated glass windows, various geometric and material parameters are investigated to determine their effect in minimizing stress wave propagation through the three-layer system to the critical inside ply. Parameters investigated include the thickness of each layer of the system and the viscoelastic properties of the PVB interlayer. © 1997 Elsevier Science Ltd

A New Algorithm to Measure the Convergence of PSO with an Application to Hydronic Design in Buildings

The particle swarm optimization (PSO) method is one of the simplest methods to apply in order to solve HVAC engineering design optimization problems. The effective application of this method in design requires an appropriate criterion for convergence and a good estimate of the number of particles to use. A common way to check for convergence in many iterative methods is to monitor the change in the objective function. However, in this paper, the authors propose using the distribution of particles to determine the convergence of the PSO method. Because of the variety of objective functions that may be possible in HVAC design, the authors investigate the rate of convergence and the appropriate number of particles using some representative test functions as well as a practical hydronic design problem. The hydronic problem simulates closed-loop systems starting with two floors and a basement to 28 floors and a basement. The results show that the PSO method does not always convergetothe solutionwhen aninsufficient number of particles are used and may be too costly if too many particles are used. For the hydronic design in this study, the recommended number of particles is eight for a two-floor building increasing to 32 for a 28-floor building. In other HVAC design problems, the same number of particles may be used to start the iteration proces

Modeling Interply Debonding in Laminated Architectural Glass Subject to Low Velocity Impact

Standard finite element wave propagation codes are useful for determining stresses caused by the impact of one body with another; however, their applicability to a laminated system such as architectural laminated glass is limited because the important interlayer delamination process caused by impact loading is difficult to model. This paper presents a method that allows traditional wave propagation codes to model the interlayer debonding of laminated architectural glass subject to low velocity, small missile impact such as that which occurs in severe windstorms. The method can be extended to any multilayered medium with adhesive bonding between the layers. Computational results of concern to architectural glazing designers are presented

Modelling Fracture in Laminated Architectural Glass Subject to Low Velocity Impact

Standard finite element wave propagation codes are useful for determining stresses caused by colliding bodies; however, their applicability to brittle materials is limited because an accurate treatment of the fracture process is difficult to model. This paper presents a method that allows traditional wave propagation codes to model low velocity, small missile impact in laminated architectural glass such as that which occurs in severe windstorms. Specifically, a method is developed to model typical fractures that occur when laminated glass is impacted by windborne debris. Computational results of concern to architectural glazing designers are presented

Low Velocity Impact Resistance of Laminated Architectural Glass

Recently developed finite element algorithms are used to study the effect of glass ply geometry on low velocity, small missile impact resistance of laminated architectural glass. The impacts studied are those typically found during severe windstorms, in which debris such as roof gravel can attain sufficient velocity to break windows in large high rise buildings. Outside ply fracture and interlayer debonding are both incorporated in the finite element analysis. It is shown that glass ply geometry can significantly affect the impact resistance of laminated glass. Three-layer laminates are shown to offer better impact resistance than five-layer and seven-layer laminates of the same overall thickness. For three-layer laminates of the same overall thickness, those with thin outside glass plies provide better impact resistance than those with thick ones

Designing HVAC systems using particle swarm optimization

Many design and operating goals in HVAC systems are optimization problems. For example, building operators want to determine the combination of equipment and set-points that result in the most energy-efficient operating conditions. Similarly, HVAC system designers want to determine the best combination of equipment, components, and operating conditions that provide minimum lifecycle cost. In both problems, the goal is to find an optimal set of system design variables. The purpose of this work is to apply an optimization technique known as particle swarm optimization to the design and operation of HVAC systems. This algorithm is based on the idea of swarms of animals, such as flying birds or insects, searching for food. In these swarms, each member gains knowledge from the whole and in turn contributes its individual knowledge back to the swarm. The result is a very efficient way to find the best available food source. The particle swarm optimization algorithm is well suited to computers with multiple processors and to HVAC problems, because it does not require continuous or well-behaved mathematical functions. Another advantage of the method is that it is remarkably simple to implement. This article illustrates the particle swarm optimization algorithm by applying it to the design of an HVAC piping system