Patent Application
20180239848
The invention generally relates to computer aided mechanical engineering analysis, more particularly to methods and systems for performing time-marching simulation of a physical domain in response to an explosion using a combination of simulated gas particles representing the blast source and smoothed-particle hydrodynamics (SPH)) particles representing the physical domain.
Continuum mechanics has been used for simulating continuous matter such as solids and fluids (i.e., liquids and gases). Differential equations are employed in solving problems in continuum mechanics. Many numerical procedures have been used, including but not limited to, finite element method (FEM), meshfree methods such as discrete element method (DEM), Smoothed-particle Hydrodynamics (SPH), and etc.
There are limitations/drawbacks to these numerical procedures for numerically simulating a continuum physical domain in response to an explosion. For example, FEM requires a mesh that would result to numerical singularity (i.e., unsolvable numerical problem) when the physical domain experienced a large deformation, DEM is more suitable for objects that are not tightly coupled (e.g., sands), while SPH suffers difficulty of imposing boundary conditions.
Therefore, it would be desirable to have improved methods that can more realistically conduct a numerical simulation of a physical domain in response to an explosion.
This section is for the purpose of summarizing some aspects of the invention and to briefly introduce some preferred embodiments. Simplifications or omissions in this section as well as in the abstract and the title herein may be made to avoid obscuring the purpose of the section. Such simplifications or omissions are not intended to limit the scope of the invention.
Numerical blast simulation methods and systems are disclosed. According to one aspect of the invention, a method of obtaining numerically simulated behaviors of a physical domain in response to an explosion. The method comprises the following: a smoothed-particle method (SPH) model containing a plurality of SPH particles representing a physical domain is received in a computer system having at least one application module installed thereon. Each SPH particle is associated with an influence function having a domain of influence. Using the application module, a blast source model containing a group of at least one simulated gas particle is created. The blast source model, defined by a set of explosion characteristics, represents the explosion just before impacting the physical domain. Each simulated gas particle is associated with a set of properties that includes a mass, a velocity vector and a location. Numerically calculated domain behaviors in response to the explosion are obtained by conducting a time-marching simulation for a predetermined duration in a plurality of solution cycles using the SPH model and the blast source model, the domain behaviors are a result of combined interactions between said each simulated gas particle and a corresponding subgroup of the SPH particles.
According to another aspect, the result of combined interactions are computed as follows: (a) determining which of the SPH particles to be included in the corresponding subgroup for each simulated gas particle based on a subgroup determination rule; (b) calculating a representative location of the subgroup using a formula algebraically combining respective properties of those SPH particles determined to be included in the subgroup; (c) performing numerical energy exchange between said each simulated gas particle and the subgroup based on a set of energy exchange rules; and (d) updating the set of properties of said each simulated gas particle and respective locations of the SPH particles from the numerical energy exchange for next solution cycle.
Other objects, features, and advantages of the invention will become apparent upon examining the following detailed description of an embodiment thereof, taken in conjunction with the attached drawings.
These and other features, aspects, and advantages of the invention will be better understood with regard to the following description, appended claims, and accompanying drawings as follows:
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will become obvious to those skilled in the art that the invention may be practiced without these specific details. The descriptions and representations herein are the common means used by those experienced or skilled in the art to most effectively convey the substance of their work to others skilled in the art. In other instances, well-known methods, procedures, components, and circuitry have not been described in detail to avoid unnecessarily obscuring aspects of the invention.
Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Further, the order of blocks in process flowcharts or diagrams representing one or more embodiments of the invention do not inherently indicate any particular order nor imply any limitations in the invention.
Embodiments of the invention are discussed herein with reference to
Referring first to
Process 100 starts by receiving a smoothed-particle hydrodynamics method (SPH) model representing a physical domain (e.g., a structure) in a computer system (e.g., computer system 600 of
Two other example SPH models 310-320 are shown in
Next, at action 104, process 100 using the application module creates a blast source model, which contains a group of at least one simulated gas particle. Each simulated gas particle is associated with a set of properties that includes a mass, a velocity vector and a location. As shown in
Then, at action 106, the numerically calculated domain behaviors are obtained by conducting a time-marching simulation for a predetermined duration (i.e., total simulation time) using the SPH model represent the physical domain and the blast source model representing the explosion. The time-marching simulation contains a number of solution cycles each representing a snapshot in time within the predetermined duration. Time-marching simulation can be achieved with either implicit or explicit solution scheme. The behaviors of the physical domain are a result of combined interactions between each simulated gas particle and a corresponding subgroup of the SPH particles. The flowchart in
Next, at action 110b, procedure 110 calculates a representative location of the subgroup using a formula algebraically combining respective properties of those SPH particles determined to be included in the subgroup. The formula can employ a number of known schemes, for example, simply average, weighted average, etc. In one embodiment, the representative location is the geometric centroid of the subgroup. For example,
Then, at action 110c, numerical energy exchange between the simulated gas particle 510 and the subgroup 524 is performed in accordance with a set of energy exchange rules. For example, the energy exchange rules are based on the energy conservation principles.
At action 110d shown in
Moreover, the scenario shown in
According to one aspect, the invention is directed towards one or more computer systems capable of carrying out the functionality described herein. An example of a computer system 600 is shown in
Computer system 600 also includes a main memory 608, preferably random access memory (RAM), and may also include a secondary memory 610. The secondary memory 610 may include, for example, one or more hard disk drives 612 and/or one or more removable storage drives 614, representing a floppy disk drive, a magnetic tape drive, an optical disk drive, etc. The removable storage drive 614 reads from and/or writes to a removable storage unit 618 in a well-known manner. Removable storage unit 618, represents a floppy disk, magnetic tape, optical disk, etc. which is read by and written to by removable storage drive 614. As will be appreciated, the removable storage unit 618 includes a computer usable storage medium having stored therein computer software and/or data.
In alternative embodiments, secondary memory 610 may include other similar means for allowing computer programs or other instructions to be loaded into computer system 600. Such means may include, for example, a removable storage unit 622 and an interface 620. Examples of such may include a program cartridge and cartridge interface (such as that found in video game devices), a removable memory chip (such as an Erasable Programmable Read-Only Memory (EPROM), Universal Serial Bus (USB) flash memory, or PROM) and associated socket, and other removable storage units 622 and interfaces 620 which allow software and data to be transferred from the removable storage unit 622 to computer system 600. In general, Computer system 600 is controlled and coordinated by operating system (OS) software, which performs tasks such as process scheduling, memory management, networking and I/O services.
There may also be a communications interface 624 connecting to the bus 602. Communications interface 624 allows software and data to be transferred between computer system 600 and external devices. Examples of communications interface 624 may include a modem, a network interface (such as an Ethernet card), a communications port, a Personal Computer Memory Card International Association (PCMCIA) slot and card, etc. Software and data transferred via communications interface 624. The computer 600 communicates with other computing devices over a data network based on a special set of rules (i.e., a protocol). One of the common protocols is TCP/IP (Transmission Control Protocol/Internet Protocol) commonly used in the Internet. In general, the communication interface 624 manages the assembling of a data file into smaller packets that are transmitted over the data network or reassembles received packets into the original data file. In addition, the communication interface 624 handles the address part of each packet so that it gets to the right destination or intercepts packets destined for the computer 600. In this document, the terms “computer program medium”, “computer readable medium”, “computer recordable medium” and “computer usable medium” are used to generally refer to media such as removable storage drive 614 (e.g., flash storage drive), and/or a hard disk installed in hard disk drive 612. These computer program products are means for providing software to computer system 600. The invention is directed to such computer program products.
The computer system 600 may also include an input/output (I/O) interface 630, which provides the computer system 600 to access monitor, keyboard, mouse, printer, scanner, plotter, and alike.
Computer programs (also called computer control logic) are stored as application modules 606 in main memory 608 and/or secondary memory 610. Computer programs may also be received via communications interface 624. Such computer programs, when executed, enable the computer system 600 to perform the features of the invention as discussed herein. In particular, the computer programs, when executed, enable the processor 604 to perform features of the invention. Accordingly, such computer programs represent controllers of the computer system 600.
In an embodiment where the invention is implemented using software, the software may be stored in a computer program product and loaded into computer system 600 using removable storage drive 614, hard drive 612, or communications interface 624. The application module 606, when executed by the processor 604, causes the processor 604 to perform the functions of the invention as described herein.
The main memory 608 may be loaded with one or more application modules 606 that can be executed by one or more processors 604 with or without a user input through the I/O interface 630 to achieve desired tasks. In operation, when at least one processor 604 executes one of the application modules 606, the results are computed and stored in the secondary memory 610 (i.e., hard disk drive 612). The status of the analysis is reported to the user via the I/O interface 630 either in a text or in a graphical representation upon user's instructions.
Although the invention has been described with reference to specific embodiments thereof, these embodiments are merely illustrative, and not restrictive of, the invention. Various modifications or changes to the specifically disclosed exemplary embodiments will be suggested to persons skilled in the art. For example, whereas the example blast source model and the physical domain have been shown and described in two-dimensional space, the blast source model and the physical domain can be in three-dimensional space for the invention. In summary, the scope of the invention should not be restricted to the specific exemplary embodiments disclosed herein, and all modifications that are readily suggested to those of ordinary skill in the art should be included within the spirit and purview of this application and scope of the appended claims.
