Patent Application
20240054985
The present disclosure relates generally to sound absorbing devices, and particularly to sound absorbing devices that include acoustic resonators.
Acoustic resonators, e.g., Helmholtz resonators and quarter-wave tubes, are used for acoustic absorption of specific frequency ranges. In addition, multiple acoustic resonators of different sizes can be used for broadband acoustic absorption, however such structures can be cost and structurally prohibitive.
The present disclosure addresses issues related to the use of acoustic resonators for broadband acoustic absorption, and other issues related to acoustic absorption.
This section provides a general summary of the disclosure and is not a comprehensive disclosure of its full scope or all of its features.
In one form of the present disclosure, a sound absorbing device includes an acoustic resonator with an opening and at least one fabric layer extending across the opening. In addition, the at least one fabric layer includes actuatable liquid crystal elastomer (LCE) fibers such that the at least one fabric layer is configured to change its average pore size as a function of temperature.
In another form of the present disclosure, a sound absorbing device includes an acoustic resonator with an opening and at least one fabric layer extending across the opening. In addition, the at least one fabric layer includes reversible actuatable liquid crystal elastomer (LCE) fibers such that an average pore size of the at least one fabric layer increases with decreasing temperature and decreases with increasing temperature.
In still another form of the present disclosure, a sound absorbing device includes an acoustic resonator with an opening and at least one fabric layer extending across the opening. The at least one fabric layer includes reversible actuatable liquid crystal elastomer (LCE) fibers such that an average pore size of the at least one fabric layer increases with decreasing temperature and decreases with increasing temperature. The sound absorbing device also includes at least one of a heater configured to heat the at least one fabric layer such that the average pore size of the at least one fabric decreases and a cooler configured to cool the at least one fabric layer such that the average pore size of the at least one fabric increases. And in some variations a controller configured to command at least one of the heater to heat to the at least one fabric layer and the cooler to cool the at least one fabric layer is included.
Further areas of applicability and various methods of enhancing the above technology will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The present teachings will become more fully understood from the detailed description and the accompanying drawings, wherein:
The present disclosure provides sound absorbing devices with one or more acoustic resonators (referred to herein simply as “acoustic resonator”) decorated with fabric. The acoustic resonator includes a chamber with a cavity and an opening that provides fluid communication between an interior of the chamber and an exterior of the chamber. The chamber without the fabric is a lossy resonator for a predefined narrow range of acoustic frequencies and a lossless resonator for acoustic frequencies outside the predefined narrow range. However, sound absorbing devices according to the teachings of the present disclosure cover (decorate) the opening of the chamber with at least one fabric layer such that the acoustic resonator is a lossy acoustic resonator for acoustic frequencies outside the predefined narrow range of the chamber. In addition, the at least one fabric layer is configured to desirably change its average pore size as a function of temperature such that the range acoustic frequencies absorbed by the sound absorbing devices can be adjusted. For example, in some variations, the at least one fabric layer includes actuatable liquid crystal elastomer (LCE) fibers that change at least one of shape and dimension as a function of temperature such that the average pore size of the at least one fabric layer changes as a function of temperature. And in such variations, the range of acoustic frequencies outside the predefined narrow range of the chamber can be adjusted by changing the temperature of the at least one fabric layer. Stated differently, the sound absorbing devices according to the teachings of the present disclosure provide acoustic dissipation for a broad range of acoustic frequencies using a simple design or structure.
Referring to
where ‘S’ is the speed of sound. In addition, the acoustic resonator 100 can absorb a band of frequencies and reemit the frequencies with the opposite phase such that the reemitted frequencies interfere with the incoming sound waves via attenuation.
The at least one fabric layer 150 has a predefined thickness, an average pore size and an average porosity at a predefined temperature (e.g., room temperature≅23° C.), and can be made or formed from any type of fabric suitable for use to enhance acoustic loss. Non-limiting examples of fabric include silk, wool, linen cotton, rayon, nylon, polyesters, and combinations thereof, including woven fabrics such as plain weave fabric, twill weave fabric, and satin weave fabric. It should be understood that fabric generally absorbs acoustic waves by converting acoustic energy of acoustic waves into heat.
The at least one fabric layer 150 also includes actuatable LCE fibers 152 (
Not being bound by theory, the actuatable LCE fibers 152 can include cross-linked polymer networks that contain rigid, anisotropic mesogenic units incorporated into the polymer chains. And due to the anisotropic nature of the anisotropic mesogenic units, the actuatable LCE fibers 152 exhibit a liquid crystalline structure in which the mesogenic units have an orientational order but remain individually mobile and can flow with respect to one another. For example, in a “nematic phase,” the mesogenic units of the actuatable LCE fibers are preferentially aligned in a given direction but have no positional order and no crystalline regularity. Accordingly, when the mesogenic units are topologically fixed via incorporation into a crosslinked polymer network, an overall distortion in the dimensions of the polymer network occurs through liquid crystalline phase transition. For example, in some variations the actuatable LCE fibers exhibit up to 300% uniaxial deformation via a liquid crystalline phase transition and such deformation is used to control and change the average pore size of the at least one fabric layer 150 as described in greater detail below. Also, non-limiting methods or process of manufacturing the actuatable LCE fibers 152 include electro spinning to form electro spun actuatable LCE fibers, direct ink writing to form direct ink write actuatable LCE fibers, among others.
Still referring to
In at least one variation, the heating device 160 is a heater configured to blow heated gas (e.g., air) onto the actuatable LCE fibers 152 and/or the cooling device is a cooler configured to blow cooled gas onto the actuatable LCE fibers 152. In another variation, the heating device 160 includes a radiate heater configured to heat the actuatable LCE fibers via heat radiation. And in some variations the heating device 160 includes one or more electrical wires 162 (e.g., a copper wire) in contact with the at least one fabric layer 150 and an electrical power source 161 configured to supply electrical current to the one or more electrical wires 162, In such variations the one or more electrical wires 162 are desirably heated from a first temperature to a second temperature and the actuatable LCE fibers 152 are heated via heat conduction from the one or more electrical wires 162.
Referring to
It should be understood that the change in average pore size of the at least one fabric layer 150 is executed or enabled by actuation of the actuatable LCE fibers 152. For example, in some variations the actuatable LCE fibers decrease in length (i.e., contract) with an increase in temperature. In such variations,
In other variations, the actuatable LCE fibers decrease in length with a decrease in temperature. In such variations,
In some variations, the average pore size of the pores 153 is controlled and adjusted between about 0.1 micrometers (μm) and about 500 μm. In at least one variation, the average pore size of the pores 153 is controlled and adjusted between about 0.2 μm and about 200 μm. And in some variations, the average pore size of the pores 153 is controlled and adjusted between about 0.5 μm and about 100 μm.
Accordingly, it should be understood from
While
Referring to
Referring now to
It should be understood from the teachings of the present disclosure that sound absorbing devices that include one or more acoustic resonators decorated with fabric are provided. The fabric can be at least one fabric layer that absorbs acoustic frequencies generally not absorbed by the one or acoustic resonators without the at least one fabric layer. That is, average pore size, the range of pore sizes, the distance and volume of gas between at least two fabric layers, and/or the elasticity and/or vibration properties of a fabric layer are adjustable such that an increased range of acoustic frequencies that are absorbed by the sound absorbing device is provided.
The preceding description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. Work of the presently named inventors, to the extent it may be described in the background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present technology.
As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical “or.” It should be understood that the various steps within a method may be executed in different order without altering the principles of the present disclosure. Disclosure of ranges includes disclosure of all ranges and subdivided ranges within the entire range.
The headings (such as “Background” and “Summary”) and sub-headings used herein are intended only for general organization of topics within the present disclosure and are not intended to limit the disclosure of the technology or any aspect thereof. The recitation of multiple variations or forms having stated features is not intended to exclude other variations or forms having additional features, or other variations or forms incorporating different combinations of the stated features.
As used herein the terms “generally” and “about” when related to numerical values herein refers to known commercial and/or experimental measurement variations or tolerances for the referenced quantity. In some variations, such known commercial and/or experimental measurement tolerances are +/−10% of the measured value, while in other variations such known commercial and/or experimental measurement tolerances are +/−5% of the measured value, while in still other variations such known commercial and/or experimental measurement tolerances are +/−2.5% of the measured value. And in at least one variation, such known commercial and/or experimental measurement tolerances are +/−1% of the measured value.
The terms “a” and “an,” as used herein, are defined as one or more than one. The term “plurality,” as used herein, is defined as two or more than two. The term “another,” as used herein, is defined as at least a second or more. The terms “including” and/or “having,” as used herein, are defined as comprising (i.e., open language). The phrase “at least one of . . . and . . . ” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. As an example, the phrase “at least one of A, B, and C” includes A only, B only, C only, or any combination thereof (e.g., AB, AC, BC, or ABC).
As used herein, the terms “comprise” and “include” and their variants are intended to be non-limiting, such that recitation of items in succession or a list is not to the exclusion of other like items that may also be useful in the devices and methods of this technology. Similarly, the terms “can” and “may” and their variants are intended to be non-limiting, such that recitation that a form or variation can or may comprise certain elements or features does not exclude other forms or variations of the present technology that do not contain those elements or features.
The broad teachings of the present disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the specification and the following claims. Reference herein to one variation, or various variations means that a particular feature, structure, or characteristic described in connection with a form or variation or particular system is included in at least one variation or form. The appearances of the phrase “in one variation” (or variations thereof) are not necessarily referring to the same variation or form. It should be also understood that the various method steps discussed herein do not have to be carried out in the same order as depicted, and not each method step is required in each variation or form.
The foregoing description of the forms and variations has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular form or variation are generally not limited to that particular form or variation, but, where applicable, are interchangeable and can be used in a selected form or variation, even if not specifically shown or described. The same may also be varied in many ways. Such variations should not be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
