A Study of the Dynamic Response of Carbon Fiber Reinforced Epoxy (CFRE) Prepregs for Musical Instrument Manufacturing

Abstract

Composite materials are presented in a wide variety of industrial sectors as an alternative to traditionally used materials. In recent years, a new sector has increasingly used these kinds of materials: the manufacture of musical instruments. Resonances of different elements that make up the geometries of musical instruments are commonly used with the aim of enhancing aspects of the timbre. These are sensitive to the mechanical characteristics of the material, so it is important to guarantee the properties of the composite. To do this, it is not uncommon to use pre-impregnated fibers (prepregs) which allow fine control of final volumetric fractions of the composite. Autoclaving is a high-quality process used to guarantee the desired mechanical properties in a composite, reducing porosity and avoiding delamination, but significantly raising production costs. On the contrary, manufacture without autoclaving increases competitiveness by eliminating the costs associated with autoclave production. In this paper, differences in dynamic behavior are evaluated under free conditions of different Carbon Fiber Reinforced Epoxy (CFRE) prepreg boards, processed by autoclave and out-of-autoclave. The results of the complex module are presented according to the frequency, quantifying the variations in the vibratory behavior of the material due to the change of processing.

Review of Manufacturing Processes and Vibro-Acoustic Assessments of Composite and Alternative Materials for Musical Instruments

“…Prepregs consist of reinforcement fabrics pre-impregnated with the matrix, remaining in a non-cured state. They find extensive usage in instruments manufacturing [3,4,16,28,32]. The vacuum-assisted resin transfer molding (infusion or VARTM, a subcategory of RTM) [12,17,23], stands out as the secondbest process for producing high-quality composite objects.…”

“…Some resins cure at room temperature, but high-quality resins often require specific cure cycles in ovens with specific rates of temperature rise and cooling [23,28]. Autoclaves [13,16,32] represent the most advanced version of ovens, providing controlled temperature and pressure conditions for an optimized curing process. Machining, joining, and shearingforming follow for the manufacturing of every part and the assemble of the final instrument is completed.…”

Special Issue on Musical Instruments: Acoustics and Vibration

“…The paper by Ibáñez-Arnal et al [5] shifts the discussion to the physical properties of the material utilized for the realization of musical instruments, focusing on the carbon fiber reinforced epoxy (CFRE) prepregs, which could be used for new prototypes of new musical instruments. Undoubtedly, the physical characteristics of the materials strongly contribute to the overall assessment of the sound quality of the instruments.…”

Manufacturing and Structural Features with Respect to the Modal Behavior of a Carbon Fiber-Reinforced Epoxy Drum Shell

“…The shell shown in Figure 5 was processed using an autoclave method (pressure 4.05 × 10 5 Pa) laying three or more collinear plies, as shown in Figure 4. Autoclave processing allows the elimination of voids generated during the curing process, which eliminates the effects of composite damping [26]. In order to obtain the highest mechanical properties of the composite, a postcure was performed following the curve shown in Figure 5.…”