Patent Publication Number: US-2023152779-A1

Title: Perforations in a membrane for a lattice structure

Description:
BACKGROUND 
     An additive manufacturing machine can be used to form a compressible lattice structure, such as a foam layer used in consumer and sporting goods, in vehicles, and so forth. Additive manufacturing machines produce three-dimensional (3D) objects by accumulating layers of build material, including a layer-by-layer accumulation and solidification of the build material patterned from computer aided design (CAD) models or other digital representations of physical 3D objects to be formed. A type of an additive manufacturing machine is referred to as a 3D printing system. Each layer of the build material is patterned into a corresponding part (or parts) of the 3D object. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some implementations of the present disclosure are described with respect to the following figures. 
         FIG.  1    is a schematic view of a portion of a beam-based lattice structure and a perforated membrane formed using techniques or mechanisms according to some examples. 
         FIG.  2    is a block diagram of an example arrangement that includes a computer and an additive manufacturing machine, according to some examples. 
         FIGS.  3 A- 3 D  illustrate a process of defining perforations in a membrane, according to some examples. 
         FIG.  3    is a block diagram of a storage medium storing machine-readable instructions according to some examples. 
         FIG.  4 A  is a top perspective view of a portion of an assembly including a beam-based lattice structure and a perforated membrane formed according to some examples. 
         FIG.  4 B  is a bottom perspective view of a portion of the assembly including a beam-based lattice structure and a perforated membrane formed according to some examples. 
         FIG.  5    is a block diagram of a storage medium storing machine-readable instructions according to some examples. 
         FIG.  6    is a block diagram of a computer according to some examples. 
         FIG.  7    is a flow diagram of a process according to some examples. 
     
    
    
     Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements. The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings. 
     DETAILED DESCRIPTION 
     In the present disclosure, use of the term “a,” “an”, or “the” is intended to include the plural forms as well, unless the context clearly indicates otherwise. Also, the term “includes,” “including,” “comprises,” “comprising,” “have,” or “having” when used in this disclosure specifies the presence of the stated elements, but do not preclude the presence or addition of other elements. 
     Using an additive manufacturing machine to build a compressible lattice structure can allow for better control of the compression response of the compressible lattice structure then typically possible with traditional manufacturing techniques. A lattice structure is compressible based on the material used to form the lattice structure, such as a thermoplastic polyurethane material or another elastomeric material. 
     In an example, a digital representation of the compressible lattice structure can be adjusted to change of properties of the compressible lattice structure, such as volumes within the lattice structure, and/or other properties. 
     As an example, by adjusting volumes within the compressible lattice structure based on use of an additive manufacturing machine, the compressible lattice structure can provide for better breathability than foam structures formed without the adjusted volumes. Fluid flow channels can be provided within the compressible lattice structure to allow for a flow of fluid, such as air or another gas or a liquid, through the fluid flow channels. In some applications, the fluid flow channels in the compressible lattice structure allows for enhanced user comfort. For example, an airflow through the compressible lattice structure can transfer heat away from where a user’s skin touches the compressible lattice structure. As another example, the fluid flow channels can remove sweat away from the user’s skin. 
     In some scenarios, a membrane is provided between a user and the compressible lattice structure to provide a more uniform contact area, than available at the surface of the compressible lattice structure. However, if the membrane is not properly perforated, the membrane can reduce the amount of airflow, which can reduce user comfort. 
     A lattice structure can be a beam-based lattice structure, in which beams are used to define a lattice arrangement. A “beam” can refer to a generally elongated member within the lattice structure. A lattice structure can include a uniform lattice, in which cells that make up the lattice are repeated throughout the entire lattice structure. In other examples, a lattice structure can include a stochastic lattice, which uses a random arrangement of beams. 
     To improve breathability in examples where membranes are applied to lattice structures, perforations can be formed in the membranes. A “perforation” refers to a hole that extends through the entire thickness of the membrane, such that a fluid can flow through the hole. A further example benefit of forming perforations in a membrane that is contacted to a lattice structure includes allowing more effective cleaning of an overall assembly including the lattice structure and the perforated membrane based on an ability of cleaning fluids to flow through the assembly. For example, powders, uncured resin, or other particulates can be removed more easily with a perforated membrane as compared to a membrane without perforations or with improperly positioned perforations. 
     There can be hundreds or thousands of contact points between the beams of the lattice structure and the membrane. An issue associated with forming perforations in a membrane that is physically contacted to a lattice structure is that, if not properly aligned, the perforations in the membrane may intersect with some beams of the lattice structure. If beams of the lattice structure intersect a perforation in the membrane, the intersecting beams may cause a partial (or even full) blockage of fluid flow through the perforation. If there are many intersections of beams of the lattice structure with perforations of the membrane, the result may be an overall reduction in the amount of fluid flow through the membrane. In some cases, a representation of a lattice structure can be generated algorithmically, such as for a stochastic lattice structure. As a result, a human designer would not know specifically how the beams of the lattice structure will be arranged, and thus it would be impractical for the designer to specify locations for the perforations in the membrane. 
     In accordance with some implementations of the present disclosure, a system receives data representing a beam-based lattice structure and a membrane to be placed on the beam-based lattice structure, identifies intersections of beams of the beam-based lattice structure with the membrane, and identifies locations for perforations in the membrane to form a perforated membrane, where the identified locations excluding the identified intersections. The system generates a representation of the beam-based lattice structure and the perforated membrane that includes the perforations at the identified locations. The representation of the beam-based lattice structure and the perforated membrane can then be used as part of an additive manufacturing process by an additive manufacturing machine to build a 3D object. 
     In some examples, the beam-based lattice structure can be a compressible lattice structure, such as one used in items for users. Items including compressible lattice structures can include a car seat, home furniture, clothing, bags, and so forth, which can come into contact with users. In other examples, compressible lattice structures can be used for non-user applications (an application in which the lattice structure is not intended to be used by humans). Moreover, lattice structures may be rigid instead of being compressible. Materials used to form lattice structures can include any or some combination of the following: polymer, metal, ceramic, glass, and so forth. 
     In other examples, the lattice structure can be non-compressible. 
     A membrane provided on a lattice structure can be formed of any or some combination of the following materials: polymer, ceramic, metal, and so forth. In some example, the membrane and the lattice structure can be built by an additive manufacturing machine as a single object. In other examples, the membrane can be built separately from the lattice structure, and then the membrane can be attached to the lattice structure. 
     Although reference is made to forming a lattice structure and a membrane using an additive manufacturing machine, it is noted that techniques or mechanisms according to some implementations can be built using other types of manufacturing machines, such as a laser cutting machine, a computer numerical control (CNC) machine, and so forth. 
       FIG.  1    is a perspective view of a portion of an assembly that includes a beam-based lattice structure  102  and a perforated membrane  104  that is physically contacted to a surface of the lattice structure  102 . Some of the perforations of the perforated membrane  104  are labelled with the reference numeral  108 . 
     Although  FIG.  1    shows the perforated membrane  104  as being provided just on one surface of the lattice structure  102 , it is noted that in other examples, the perforated membrane  104  can be provided on multiple surfaces of the lattice structure  102 . In some examples, the perforated membrane  104  can even fully wrap around the exterior surface(s) of the lattice structure  102 . 
     The beam-based lattice structure  102  includes various beams (with some of the beams identified with reference numeral  106 ). The beams are connected to one another in a generally lattice-like arrangement to form the lattice structure  102 . In some examples, the lattice structure  102  is a stochastic lattice structure, which includes a random arrangement of beams. In other examples, the lattice structure  102  is a uniform lattice structure, which includes repeating cells throughout the lattice structure, or in a portion of the lattice structure (such as the portion that provides the outermost surface of the lattice structure  102 ). A “cell” of a uniform lattice structure includes an arrangement of beams. The cell is repeated throughout the entire lattice structure or a portion of the lattice structure, such that a uniform arrangement of beams is provided in the lattice structure. 
     The assembly depicted in  FIG.  1    can be built using an additive manufacturing machine. 
     The beam-based lattice structure  102  includes fluid flow channels, and the perforations  108  in the perforated membraned  104  are aligned with the fluid flow channels to provide fluid flow through the perforations and the fluid flow channels. 
     An additive manufacturing machine such as a 3D printing system can use a build material, such as a powdered build material composed of particles in the form of fine powder or granules, to build a 3D object. The powdered build material can include metal particles, plastic particles, polymer particles, ceramic particles, glass particles, or particles of other powder-like materials. In some examples, a build material powder may be formed from, or may include, short fibers that may, for example, have been cut into short lengths from long strands or threads of material. 
     In some examples of additive manufacturing machines, as part of the processing of each layer of build material, liquid agents can be dispensed by liquid agent dispensers (such as through a printhead or another fluid dispensing device) into a layer of build material. In examples where the build material is a non-metallic build material such as plastic or polymer, the applied liquid agents can include a fusing agent (which is a form of an energy absorbing agent) that absorbs heat energy emitted from an energy source used in the additive manufacturing process. For example, after a layer of build material is deposited onto a build platform (or onto a previously formed layer of build material) in the additive manufacturing machine, a fusing agent with a target pattern can be deposited on the layer of build material. The target pattern can be based on an object model (or more generally, a digital representation) of the physical 3D object that is to be built by the additive manufacturing machine. 
     If a metallic powdered build material is used, then an additive manufacturing machine can apply a binder agent (which is another form of a liquid agent) to layers of powdered metal build material such that the binder agent is applied to selected portions of each layer. In some examples, the binder agent can include a liquid functional agent (LFA), which may be a water-based binder agent that includes latex, solvents, and surfactants. Alternatively, the binder agent can include a pre-wetting liquid that can be applied to promote or inhibit infiltration of another binder agent. As each layer of the powdered metal build material is deposited, a binder agent can subsequently be dispensed by liquid agent dispensers (such as through a printhead or another fluid dispensing device) to the layer. Portions of the powdered metal build material where the binder agent is applied are bound together by the binder agent. The binder agent can include an ultraviolet-curable binder agent, heat-curable binder agent, and so forth. After the layers of powdered metal build material have been deposited and the binder agent has been applied to locations of each layer of the powdered metal build material, curing (e.g., based on application of heat or ultraviolet light in the additive manufacturing machine) of the binder agent in the layers of the powdered metal build material produces a so-called “green part.” The green part is de-powdered to remove any external unbound build material powder. Afterwards, the green part can be transferred to an oven, where the binder agent can be decomposed from a thermal process, and where the bound build material powder (e.g., metal particles, etc.) are sintered together to form a highly dense 3D object. Sintering refers to coalescing powdered particles to form a solid mass with a higher density than the green part. 
     In further examples, an additive manufacturing machine can include a selective laser melting (SLM) or selecting laser sintering (SLS) printer, which employs a laser-based fabrication technique that does not involve dispensing of liquid agents (e.g., the fusing agent or binder agent discussed above). 
       FIG.  2    is a block diagram of an example arrangement that includes a computer  202  and an additive manufacturing machine  204  (or alternatively, another type of manufacturing machine). Although the computer  202  is separate from the additive manufacturing machine  204  in some examples, it is noted that the computer  202  can be part of the additive manufacturing machine  204  in other examples. In the latter examples, the computer  202  can be implemented as a controller in the additive manufacturing machine  204 . In examples where the computer  202  is separate from the additive manufacturing machine  204 , the computer  202  is able to communicate with the additive manufacturing machine  204  over a communications link  206 , such as a network, a short-range wireless link, and so forth. 
     The computer  202  includes a 3D object representation forming engine  208  that forms a digital representation of a 3D object for use by the additive manufacturing machine  204  in building a 3D object. 
     As used here, an “engine” can refer to a hardware processing circuit, which can include any or some combination of a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, or another hardware processing circuit. Alternatively, an “engine” can refer to a combination of a hardware processing circuit and machine-readable instructions (software and/or firmware) executable on the hardware processing circuit. 
     The 3D object representation forming engine  208  includes a membrane perforations defining logic  210  for identifying locations of perforations in a membrane that is to be attached to a lattice structure, such as to form the assembly shown in  FIG.  1   . The membrane perforations defining logic  210  can be part of the hardware processing circuit of the 3D object representation forming engine  208 , or can be part of the machine-readable instructions of the 3D object representation forming engine  208 . In other examples, the membrane perforations defining logic  210  can be separate from the 3D object representation forming engine  208 . 
     The 3D object representation forming engine  208  receives data ( 212 ) representing a beam-based lattice structure and data ( 214 ) representing a (un-perforated) membrane to be placed on the beam-based lattice structure. 
     The membrane perforations defining logic  210  identifies intersection points at which beams of the beam-based lattice structure intersects with the membrane. Based on the identified intersection points, the membrane perforations defining logic  210  identifies locations for perforations in the membrane to form a perforated membrane. The identified locations for the perforations in the membrane excludes the identified intersection points, so as to prevent intersection of beams of the beam-based lattice structure with the perforations. 
     The 3D object representation forming engine  208  generates a digital representation ( 216 ) of the beam-based lattice structure and the perforated membrane that includes the perforations at the identified locations. The digital representation ( 216 ) of the beam-based lattice structure and the perforated membrane is provided to the additive manufacturing machine  204 , which builds a 3D object including an assembly that includes the beam-based lattice structure and the perforated membrane. 
     The additive manufacturing machine  204  includes a controller  218  that can be used to control an additive manufacturing process in the additive manufacturing machine  204  for building a 3D object. As used here, a “controller” can refer to a hardware processing circuit, which can include any or some combination of a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, a digital signal processor, or another hardware processing circuit. Alternatively, a “controller” can refer to a combination of a hardware processing circuit and machine-readable instructions (software and/or firmware) executable on the hardware processing circuit. 
     The controller  218  receives the digital representation ( 216 ) of the beam-based lattice structure and the perforated membrane generated by the 3D object representation forming engine  208 , and the controller  218  controls an additive manufacturing process according to the digital representation  216  to build a 3D object including the assembly that includes the beam-based lattice structure and the perforated membrane. 
     An additive manufacturing process includes the spreading of a layer of a powdered build material across a build bed  220  by a spreader assembly  222 , and the dispensing of a liquid agent by a fluid dispensing device  224 . The controller  218  is able to control an operation of the spreader assembly  222 , the fluid dispensing device  224 , and other components (e.g., heaters, etc.) that are not shown. 
     Initially, before a 3D build operation has started, the build bed  220  includes the upper surface of a build platform  226  in the additive manufacturing machine  204 . After build material layers have been spread over the build platform  226  and processed on a layer-by-layer basis, the build bed  220  would include any previously formed part(s) of the 3D object based on the previously processed build material layer(s). More generally, a “build bed” refers to a structure onto which a build material layer can be spread for processing, where the structure can include just the upper surface of the build platform  226 , or alternatively, can further include any previously formed part(s) of a 3D object. 
     The spreader assembly  222  is used to spread a powdered build material across the build bed  220 . The spreader assembly  222  (including a roller, a blade, etc.) is moveable in a spread direction  223  (along a spread axis) to spread the powdered build material from a supply of the powdered build material across the build bed  220 . In further examples, the spreader assembly  222  is moveable in multiple spread directions (along multiple respective spread axes) to spread a powdered build material across the build bed  220 . 
     After a layer of powdered build material has been spread across the build bed  220  by the spreader assembly  222 , the fluid dispensing device  224  is used to dispense a liquid agent to selected portions of the layer of powdered build material. The fluid dispensing device  224  (e.g., a printhead) includes nozzles to dispense the liquid agent (such as generally in a downward direction  225  in the view shown in  FIG.  2   ) to a layer of build material that is part of the build bed  220 . In other examples, the additive manufacturing machine  204  can include multiple fluid dispensing devices  224 . 
     In some examples, the fluid dispensing device  224  can be mounted to a moveable carriage (not shown) in the additive manufacturing machine  204 . During a build process, the carriage can move back and forth to move the fluid dispensing device  224  along a scan axis, to dispense liquid agents to the layer of build material during a build operation. In other examples, the fluid dispensing device  224  can be moved along multiple different scan axes. 
     The layers processed by the additive manufacturing machine  204  based on the digital representation  216  includes layers of the beam-based lattice structure and layers of the perforated membrane as represented by the digital representation  216 . 
       FIGS.  3 A- 3 D  illustrate a process performed by the membrane perforations defining logic  210  in the computer  202  ( FIG.  2   ) to identify locations for perforations in a membrane  302 . 
     Based on the data ( 212 ) representing a beam-based lattice structure and the data ( 214 ) representing the (un-perforated) membrane to be placed on the beam-based lattice structure, the membrane perforations defining logic  210  identifies intersection points at which the beams of the beam-based lattice structure intersect the membrane  302 . The intersection points are identified with an “X” in  FIG.  3 A . The intersections between the beams and the membrane  302  are at points where the beams interact physically with the membrane  302  (i.e., at points where there is physical touching between the beams and the membrane  302 ). 
     Based on the data ( 212 ) representing the beam-based lattice structure, the membrane perforations defining logic  210  can identify a start point and an end point of each beam in the beam-based lattice structure. A start point and an end point refer to geometric points in a 3D space containing the beam-based lattice structure. For example, the data ( 212 ) representing the beam-based lattice structure can define the beams using respective pairs of geometric points that represent a respective start point and end point. In other examples, the data ( 212 ) representing the beam-based lattice structure can be a graphical representation of the beams of the beam-based lattice structure. 
     Based on the intersection points (identified by “X” in  FIG.  3 A ), the membrane perforations defining logic  210  can use triangulation to identify triangles that connect the intersection points. For example, the triangulation can include Delaunay triangulation, such as a 2D Delaunay triangulation (performed in a 2D space) or a 3D Delaunay triangulation (performed in a 3D space). As another example, the triangulation can include Voronoi tessellation. 
     Although  FIG.  3 A  shows the intersection points as being part of a single plane, it is noted that the intersection points can actually exist in multiple planes in a 3D space. 
       FIGS.  3 A- 3 D  illustrate intersection points in a single 2D plane for ease of explanation. Techniques or mechanisms according to some implementations of the present disclosure for identifying locations for perforations can be extended to intersection points in 3D space, such as based on use of 3D Delaunay triangulation. 
       FIG.  3 B  shows triangles formed by connecting the intersection points (each represented by an “X” in  FIG.  3 B ). If a Delaunay triangulation is used, each of the triangles is generated from a circumcircle (or circumsphere in the 3D case) based on three distinct original intersection points. For these circumcircles (or circumspheres) to be valid, each circumcircle (or circumsphere) does not enclose any intersection point. As a result, each triangle that is defined does not contain any intersection point. Thus, each triangle defines a region on the external surface of the membrane  302  where a perforation can be created. 
     The membrane perforations defining logic  210  fits incircles into respective triangles. An incircle is an inscribed circle of a polygon (which in the present examples is a triangle); the circle is located completely within the triangle and is tangent to each of the triangle’s sides. 
     As shown in  FIG.  3 C , an incircle that is fitted into each triangle is the largest circle contained within the respective triangle. In some examples, incircles can be fitted into all of the triangles defined by the intersection points on the membrane  302 . In other examples, incircles can be fitted into some of the triangles defined by the intersection points on the membrane  302 . 
     To improve the structural integrity of the membrane  302 , the radius of each incircle  304  can be reduced by a specified amount such that connecting portions can be formed in the membrane  302  to allow for structural integrity of the membrane  302 . The reduction of the incircles produces reduced radius circles  306  as shown in  FIG.  3 D , in which each reduced radius circle  306  is spaced apart from the sides of the triangle in which the reduced radius circle  306  is located, such that a specified gap is provided each reduced radius circle  306  and the corresponding sides of the respective triangle. 
     The reduced radius circles  306  represent the locations where perforations are to be formed in the membrane  302 . The perforations formed can have the general size represented by the reduced radius circles  306 . Each reduced radius circle generally defines the center and maximal radius of each perforation. 
       FIG.  4 A  depicts a top perspective view of an assembly including a perforated membrane  402  formed by forming perforations according to the reduced radius circles  306  of  FIG.  3 D . The external surface of the perforated membrane  402  is visible in  FIG.  4 A . Some beams  404  of the lattice structure that are in physical contact with the perforated membrane  402  are shown in  FIG.  4 A . 
       FIG.  4 B  is a bottom perspective view that shows beams  404  contacting an inside surface of the perforated membrane  402 . 
       FIG.  5    is a block diagram of a non-transitory machine-readable or computer-readable storage medium  500  storing machine-readable instructions that upon execution cause a system to perform various tasks. The system can include the computer  202 , for example. 
     The machine-readable instructions include data reception instructions  502  to receive data (e.g.,  212  and  214  in  FIG.  2   ) representing a beam-based lattice structure and a membrane to be placed on the beam-based lattice structure. 
     The machine-readable instructions include intersection identification instructions  504  to identify intersections of beams of the beam-based lattice structure with the membrane. The intersections are at points of physical interaction between the beam-based lattice structure and the membrane. 
     The machine-readable instructions include perforation location identification instructions  506  to identify locations for perforations in the membrane to form a perforated membrane, the identified locations excluding the identified intersections. In some examples, the identifying of the locations for the perforations in the perforated membrane uses triangulation to identify triangles that connect intersection points. The identified locations for the perforations are inside the triangles. In some examples, a specified gap is defined between a perforation of the perforations and sides of a respective triangle, such as by reducing the radius of a circle fitted within each triangle. 
     The machine-readable instructions include representation generation instructions  508  to generate a representation of an object including the perforated membrane that has the perforations at the identified locations. In some examples, the generated representation can be of the object that includes both the beam-based lattice structure and the perforated membrane. In other examples, the generated representation can be of the object that includes the perforated membrane without the beam-based lattice structure; in such latter examples, the perforated membrane is to be applied to a beam-based lattice structure by the manufacturing machine. 
     In some examples, the machine-readable instructions further include machine-readable instructions to provide, to a manufacturing machine (e.g., an additive manufacturing machine or another manufacturing machine, the representation for building of the beam-based lattice structure and the perforated membrane placed on the beam-based lattice structure. 
       FIG.  6    is a block diagram of computer  600  that includes a hardware processor  602  (or multiple hardware processors). A hardware processor can include a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, or another hardware processing circuit. 
     The computer  600  includes a storage medium  604  that stores machine-readable instructions executable on the hardware processor  602  to perform various tasks. Machine-readable instructions executable on a hardware processor can refer to the instructions executable on a single hardware processor or the instructions executable on multiple hardware processors. 
     The machine-readable instructions include data reception instructions  606  to receive data (e.g.,  212 ,  214  in  FIG.  2   ) representing a beam-based lattice structure and a membrane to be placed on the beam-based lattice structure. 
     The machine-readable instructions include intersection point identification instructions  608  to identify intersection points of beams of the beam-based lattice structure with the membrane when contacted to the beam-based lattice structure. 
     The machine-readable instructions include triangle definition instructions  610  to define triangles connecting the intersection points. 
     The machine-readable instructions include perforation location identification instructions  612  to identify locations for perforations in the membrane to form a perforated membrane, the identified locations being within the triangles. In some examples, the identifying of the locations for the perforations includes defining circles inside the triangles, where each circle has a radius that is reduced from a radius of a maximum sized circle (e.g., the incircles  304  shown in  FIG.  3 C ) that can fit in a respective triangle. 
     The machine-readable instructions include representation generation instructions  614  to generate a representation of an object including the perforated membrane that has the perforations at the identified locations. 
     In some examples, the machine-readable instructions further include machine-readable instructions to provide, to a manufacturing machine, the representation for building of the beam-based lattice structure and the perforated membrane placed on the beam-based lattice structure. 
       FIG.  7    is a flow diagram of a process  700  according to some examples. The process  700  can be performed by the computer  202  or the computer  600 , for example. 
     The process  700  includes receiving (at  702 ) data representing a beam-based lattice structure and a membrane to be placed on the beam-based lattice structure, the beam-based lattice structure comprising fluid flow channels. 
     The process  700  includes identifying (at  704 ) intersections of beams of the beam-based lattice structure with the membrane. 
     The process  700  includes identifying (at  706 ) locations for perforations in the membrane to form a perforated membrane, the identified locations excluding the identified intersections, the perforations being aligned with the fluid flow channels in the beam-based lattice structure. 
     The process  700  includes generating (at  708 ) a representation of the beam-based lattice structure and the perforated membrane that includes the perforations at the identified locations. 
     The process  700  includes providing (at  710 ), to a manufacturing machine, the representation for building of the beam-based lattice structure and the perforated membrane placed on the beam-based lattice structure. 
     A storage medium (e.g.,  500  in  FIG.  5    or  604  in  FIG.  6   ) can include any or some combination of the following: a semiconductor memory device such as a dynamic or static random access memory (a DRAM or SRAM), an erasable and programmable read-only memory (EPROM), an electrically erasable and programmable read-only memory (EEPROM) and flash memory or other type of nonvolatile memory device; a magnetic disk such as a fixed, floppy and removable disk; another magnetic medium including tape; an optical medium such as a compact disk (CD) or a digital video disk (DVD); or another type of storage device. Note that the instructions discussed above can be provided on one computer-readable or machine-readable storage medium, or alternatively, can be provided on multiple computer-readable or machine-readable storage media distributed in a large system having possibly plural nodes. Such computer-readable or machine-readable storage medium or media is (are) considered to be part of an article (or article of manufacture). An article or article of manufacture can refer to any manufactured single component or multiple components. The storage medium or media can be located either in the machine running the machine-readable instructions, or located at a remote site from which machine-readable instructions can be downloaded over a network for execution. 
     In the foregoing description, numerous details are set forth to provide an understanding of the subject disclosed herein. However, implementations may be practiced without some of these details. Other implementations may include modifications and variations from the details discussed above. It is intended that the appended claims cover such modifications and variations.