Damping analysis of plates with multiple constrained layer. Pdf in this paper, an efficient constrainedlayer damping layout. Constrained layer damping cld is an effective method for. A fundamental tradeoff in the properties of a driver cone is mechanical stiffness versus mechanical damping. The purpose behind this study is to predict damping effects using method of passive viscoelastic constrained layer damping.
They combine metallic sheets with polymeric layers, and their damping is due to the dissipation of energy that occurs through the shear. The middle layer uses viscoelastic gel for damping and the outermost layers, or the restraint layers, are made of thin metal sheets to restrict the deformation of the gel. When the system flexes during vibration, shear strains develop in the damping layer and energy is lost through shear deformation of the material. This thesis with the title modelling floors with a constrained damping layer is. Analysis of active constrained layer damping in composite. Each contributes its genius to an improved understanding of the nature of damping. Decidamp fdf is a specially formulated composite material comprising a viscoelastic polymer system laminated between two layers of polyester fabric. Constrained layer damping treatments promise to be an effective method to control vibration in flexible structures. Researcharticle dynamic optimization of constrained layer damping structure for the headstock of machine tools with modal strain energy method yakaixu,1 weiguogao,1 yuhanyu,2 daweizhang,1 xiangsongzhao,1. Cld was employed through a sandwichtype structure constructed by attaching viscoelastic gel and thin metal sheets to the base. It is specifically designed to be used as a constrainedlayer damping sheet in glass reinforced plastic grp and fibreglassfoam sandwich. Constrained layer damper modelling and performance evaluation.
Acld treatments combine the best features of passive and active control of structural vibrations. Optimization of constrained layer damping for strain energy. Constrainedlayer damping cld systems are used to increase damping in stiff structures. Pdf in this paper we assess the performance of finite element models in. Vibration control through passive constrained layer. This paper presents a theoretical study of the parameters that influence sandwichtype constrained layer damper design. Optimization of active constrained layer damping of beam. Constrainedlayer damping cld is a specific method of treatment commonly used in the aerospace and military industries. A constrained layer damping toolholder was designed to machine al 7075t7451 in this study. Identification of the substancemixture and of the company 1.
Due to the constrained condition, the viscoelastic core undergo transverse shear damped deformation which produce more energy dissipation than free layer damping treatment. Therefore, pcld treatment is more applicable than acld treatment in traditional industry. Heathcote specialise in the manufacture of constrained layer dampers clds one of the most effective and weight efficient forms of passive damper available. Topology optimization of freelayer damping material on a. Optimization of segmented constrained layer damping.
Application of a constrained layer damping treatment to a. Development of constrained layer damping toolholder to. Dynamic optimization of constrained layer damping structure. In this paper, the treatment of a beam with a separate active element and passive constrained layer pcld element is investigated.
With future design iterations, damping levels several times those seen in this document will be seen with a constrained treatment applied to a landing gear system. Noise and vibration control with constrained layer damping. This method of passive damping treatment is widely used for structural. Constrained layer damping sheet, decidamp fdf pyrotek. Topology optimization of passive constrained layer damping with partial coverage on plate suffers form its high cost and complexity. A mathematical model is developed to simulate the sound radiation based on the theories of the. Pdf optimal placement of constrainedlayer damping for. An overview of constrainedlayer damping theory and. Energy dissipation using constrainedlayer damping cld is achieved by shearing a viscoelastic polymer between a base structure and a constraining layer as depicted below. One is constrained layer damping treatment in which a damping material is sandwiched by two panels that are relatively stiffer than the damping material. Constrained layer damping material reduction of vibration in circuit boards and paneltype structures using a highly damped, constrained viscoelastic material attributes the epsg cldm material effectively and efficiently reduces the amount of vibration transmitted to a structure resulting in longer fatigue life of the structure or. An acoustical topology optimization of a constrained layer damping cld plate coupled with a rigid acoustical cavity is presented to minimize the sound radiation power.
Smart constrained layer damping of functionally graded shells. Constrained layer treatments are a first alternative allowing high. Kerwin entitled damping of flexural waves by a constrained viscoelastic layer, dr. May 09, 2017 ten years ago, constrained layer damping cld was the thing in highend audio. Ross, kerwin and unger rku model for passive viscoelastic damping has been used to predict damping effects in constrained layer sandwich cantilever beam.
The optimization objective is to maximize the system loss factor for the first mode of the beam. The viscoelastic damping layer is sandwiched between two piezoelectric layers. We saw cld turntable plinths, cld shelves, cld racks, cld aftermarket feet, cld audio cables i am sure if i looked hard enough i would have found cld remote controls and power cables. Historically, constrained layer damping treatments have used a very thin adhesive layer as the damping material. A ritz galerkin approach is used to obtain discretized equations of motion. Cld may be described as a type of shearrelated energy dissipation achieved by interconnecting two or more structural materials using a relatively thin viscoelastic layer.
The 7361d material is designed to offer the maximum amount of structural damping to panel structures by shearing. The application of cld treatments to cast engine covers has been difficult due to the rough surface finish of the covers. Abstractconstrained layer damping has extensively used since. These data can guide to specify the position of the constrained layer damping patch under pressure conditions. Pdf some of the fundamental principles of constrained layer damping methodology are addressed and several mechanisms by which large. Smart constrained layer damping of functionally graded shells using verticallyobliquely reinforced piezocomposite under a thermal environment mcrayandrcbatra department of engineering science and mechanics, mc 0219, virginia polytechnic institute and state university, blacksburg, va 24061, usa received 19 january 2008, in. Constrained layer damping is a mechanical engineering technique for suppression of vibration. Constrained layer dampers heathcote industrial plastics. A sandwich is formed by laminating a damping layer in between two structural constraining base layers.
Damping treatments are typically classified into two types of layered structures. Decidamp cld was developed to meet market noise reduction requirements across automotive, marine, industrial and oem markets. This paper describes the use of multiobjective genetic algorithm moga to solve an integrated optimization problem of a rotating flexible arm with active constrained layer damping acld treatment. A parametric study was carried out using modal strain energy method to explore interaction between. Influence of sandwichtype constrained layer damper design. Constrained layer damping cld is recognized as an effective means for. Although there are different ways to reduce the noise generated by a railway wheel, most devices are based on the mechanism of increasing wheel damping. The paper also gives an insight into the fundamentals governing the dynamics and activepassive control of smart composite sandwiched plate structures to use as the potential basic building block of structures where effective vibration damping is essential to their successful operation. Dimensionless analysis of segmented constrained layer damping. Decidamp cld is a constrained layer, viscoelastic damping material, designed to reduce structural vibration and sound transmission within light gauge materials. The damping is modeled using the ghm method and the system is analyzed in the time domain.
Topology optimization of passive constrained layer damping. How best shall noisy aircraft, cars, ships, machinery, etc. Concretebased constrained layer damping springerlink. The constrained version is a viscoelastic damping material, a constraining layer, and a protective release paper.
Evolution of constrained layer damping using a cellular. Baruch is identified in chat paper as having suggested the shear damping mechanism, li the same year, a paper was presented at the collo. Finite element modelling for the investigation of inplane modes and damping shims in disc brake squeal article pdf available in journal of sound and vibration 3319. Evolution of constrained layer damping using a cellular automaton algorithm c m chia, j a rongong, and k worden department of mechanical engineering, the university of shef. A parametric study was carried out on the constrained damping layer to investigate the effect of different parameters such as concrete base, rubber layer and protection layer on the overall dynamic performance of this system. Vibration analysis of beams with multiple constrained layer. Reproduction may be achieved either by combining two selected individuals. These thin layer cld treatments have yielded exceptional results in many applications. W kung and r singh acoustics and dynamics laboratory\ department of mechanical engineering\ the ohio state university\ columbus\ ohio 32109. Constrained layer damping material, viscoelastic damping.
The optimization of the constrained layer damping for strain energy minimization of vibrating pads depend on the position of the shape of the damping patch. Constrained layer damping treatments with a thin damping polymer layer have long been used as a means to impart damping to a structure. Pdf the analysis and design of constrained layer damping. Optimization of passive constrained layer damping treatments. Nowadays, it is a very common practice for automakers to add pcld patches to the structures. Constrained and free layer damping archives vibratec engelska. Constrained layer damping material reduction of vibration in circuit boards and paneltype structures using a highly damped, constrained viscoelastic material attributes the epsg cldm material effectively and efficiently reduces the amount of vibration transmitted to a structure resulting in longer fatigue life of the structure or circuit board. Sandwichtype clds are devices that combine metallic sheets with viscoelastic layers, and they increase the damping of the railway wheel. Vibration energy is dissipated by shear distortion of the damping material due to the flexural behavior of. Vibration control through passive constrained layer damping.
Constrained layer damping cld is a driver cone technology from atc that represents another advance in driver performance one that transfers directly to system performance and the reproduction of music. Noisekiller black is a unique highly efficient damping compound developed for acoustic improvement of decks and bulkheads, vehicle chassis and other structures that are exposed to vibrations. Topology optimization for minimizing frequency response. Passive viscoelastic constrained layer damping technology for. These are usually known as containment put it in a box, absorption usually foam, isolation usually rubber or hydraulic, passive damping and active damping. A realcoded genetic algorithm for optimizing the damping. However, due to the surface roughness of this cover, a traditional thin layer cld was not feasible without a costly machining step. Cutting both the constraining layer and the viscoelastic layer, which leads to segmentation, increases the damping efficiency. Sound radiation analysis of constrained layer damping structures. Optimization design method for constrained damping layers. Constrained and free layer damping vibratec engelska.
Constrainedlayer damping applied to dcj vibration isolation. Pdf finite element modelling for the investigation of in. By 1990s, active constrained layer damping acld has begun to receive much attention. Topology optimization of passive constrained layer damping with. Topology optimization of a constrained layer damping plate. The acld treatment consists of a conventional passive constrained layer damping which is augmented with efficient active control means to control the strain of the constrained layer in response to the structural vibrations, as shown in figure 1a. Passive viscoelastic constrained layer damping application. The 7361d damping material is produced as constrained layer or non constrained layer depending on the application. May 14, 20 constrained layer damping cld is a specific method of treatment commonly used in the aerospace and military industries.
Constrained layer damping cld was employed through a sandwichtype structure constructed by attaching viscoelastic gel and thin metal sheets to the base. A highly efficient damping compound for structure borne more less noise in metal, plastic, wood etc. Moreira and rodrigues 7 used modal strain energy mse method to optimally locate passive constrained viscoelastic damping layers on structures. Typically a viscoelastic or other damping material, is sandwiched between two sheets of stiff materials that lack sufficient damping by themselves.