CAD, CAD Technology, dynamic modeling, CAD modeling

How CAD Technology benefits from Dynamic Modeling

Alexander Pope, in the 17th century, coined the phrase “A little knowledge is a dangerous thing”. This phrase holds true in many cases, because a small amount of knowledge could lead to overconfidence. An overconfident person is likely to make decisions hastily without taking all facts into account.

What does this phrase have to do with Computer Aided Design? A CAD engineer who is trained primarily to use CAD software tools, but who lacks sound theoretical training, fits this phrase in many respects. Such a CAD engineer who has successfully solved many routine design problems with CAD tools could become overconfident in his/her design skills.

The time will come when this overconfident engineer, who lacks adequate theoretical training, models a non-routine problem incorrectly and misinterprets the results. Consequently, an incorrect design for a product is implemented. Unless the design error is caught and fixed, the launched product will be an accident waiting to happen. Failure of a poorly-designed product could cost a company a lot of time, money, and loss of reputation.

Many CAD and engineering organizations are aware of such dangers, and they include Dynamic Modeling into their product design cycles. Doing so provides “checks and balances” before a design materializes into a product.

This article examines the roles that Dynamic Modeling plays in CAD-driven product design.

Specifically, the article tries to answer these questions:

  • What is Dynamic Modeling, and is it needed for all product designs?
  • Are all CAD engineers qualified to perform CAD enabled dynamic modeling?
  • What are the benefits of Dynamic Modeling?
  • How is Dynamic Modeling being used?

What Is Dynamic Modeling and Is It Needed for all Product Designs?

Dynamic modeling simulates the behavior of an object over time. In engineering, dynamic models are described in terms of causal loops or feedback and control systems.

The causal loop captures the structural makeup or components that comprise a complex system or product, and the interactions between them. Computer models are built to simulate how the system responds to time-varying states and external loads, and how the system responds over time.

Dynamic modeling is not restricted to time-variant behavior of physical structures, but it is also used for artificial intelligence, economics, psychology, political science, and many other disciplines.

Not all products require dynamic modeling. For example, stationary objects such as statues are not subjected often to time varying externals loads such as wind forces or earthquakes. Therefore, static models suffice for determining their structural integrity.

Examples of good candidates for dynamic modeling are:

  • Bridges, which experience variable loadings, wind forces, and perhaps earthquakes.
  • Offshore oil production platforms, which are subjected to ocean waves, wind, and current loadings.
  • Automobiles, which are subjected to shock loadings and aerodynamic forces.
  • Buildings and structures in earthquake-prone areas, because they endure seismic loadings. 

Are all CAD Engineers Qualified to Perform CAD Enabled Modeling?

Not all CAD engineers have the skills to perform dynamic modeling adequately. CAD software tools which provide its capabilities will incorporate them as FEA, CFD, and other software packages. The CAD engineer who has not taken advanced courses in Solid Mechanics, Fluid Mechanics, Feedback and Control Systems, Vibration Analysis, Random Mechanics, and similar courses may lack sufficient theoretical skills to adequately model and interpret non-routine design problems with CAD software.

Dynamic modeling which is performed incorrectly could produce design errors with disastrous consequences, if the errors:

  • Are not detected and corrected by peers,
  • Are not detected during design reviews,
  • Are not detected during the prototyping and testing phase.

Once a poorly designed product is launched, the consequences could mean applying fixes in the field, having a product recall, or withdrawing a product. None of these options is desirable, because it creates customer dissatisfaction, possible lawsuits, loss of income, and loss of reputation.

What are the Benefits of Dynamic Modeling?

If properly performed, Dynamic Modeling can reveal design flaws that may not show up readily during the prototyping and testing phases of the product design cycle.

Unique benefits that dynamic modeling provides include:

  • Identifying interactions between subsystems of a complex product which may be too expensive to create during physical prototyping and testing,
  • Identifying potential failure modes which should be tested in physical prototypes, before hard tooling,
  • Simulating dynamic loadings which may be difficult to create during actual testing,
  • Identifying functional limitations on the use of a product.

Although some complex systems may be difficult to model accurately, it provides extra product performance data from virtual prototypes. Testing and validation of data obtained from virtual prototypes within physical prototypes should create a robust and reliable design.

How is Dynamic Modeling being used?

A few examples should clarify the benefits that Dynamic Modeling brings to CAD design work.

  • Engineers at NIST (National Institute of Standards and Technology) are building a horizontal smokestack computer model called the Scale-Model Smokestack Simulator. The Dynamic Model will predict the amount of carbon dioxide coming out of smokestacks with 1% accuracy, compared with current measurement accuracy of 10 to 20%. This Dynamic Model will make it easier to address the problem of CO2 emissions which the EPA is concerned about.
  • The University of Le Havre uses Dynamic Modeling to efficiently calculate optimized mold measurements for a ship hull.
  • SolidWorks provides modeling software within their CAD offerings for all types of industrial robot movements. The software also translates code from one robot to another, and can import models from major CAD systems.
  • It is being used extensively to study the impact of Self Driving vehicles on traffic flow.

Conclusions

When it is used effectively and correctly, creates virtual product prototypes that can identify failure modes and functional limitations of a design at an early stage.

When dynamic modeling is used together with Additive Manufacturing (or 3D printing) for physical product prototyping, the design cycle could be significantly shortened. Consequently, reliable and cost effective products will be launched, and the cost saving will benefit both the product manufacturer and the consumer.

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3D printing, music industry, music storage, computer-aided design

How Music Industry impacted by 3D Printing

Prior to digital preservation of works of art, books were stored on microfiche, while music, pictures and movies were stored on film. One benefit of storing information in digitized form is that it can be transported electronically, so that backup copies of the information can be placed at many remote locations. Another benefit is that the fidelity of the information is preserved indefinitely.Unfortunately, it is likely that significant amounts of music, movies and works of art may have been lost forever because reliable methods of preserving music were not previously available. For example, lots of music that had been stored on wax discs and were played on phonographs, or many old movies that had been stored on reels may not be restorable. Although many original recordings have now been digitized, natural degradation of wax recordings and tapes have made large amounts of music and movies unrecoverable. Even though many old movies and music have now been digitally remastered, true fidelity of the multimedia data may have been lost.

Works of art that have the most longevity have been preserved in several forms. Some artifacts remain as carvings on stone and wood, some artifacts remain as statues, and some artifacts remain as stylus-based ink recordings on papyri, scrolls, paper, and on other media. Except for stone carvings and statues which could be considered to a reasonable extent as naturally non-destructible, recordings on wood-based products such as papyri, scrolls and paper degrade quickly in high humidity environments. Recordings on wood-based media need low humidity or vacuum storage conditions to survive over long periods of time.

It only takes a natural or man-made disaster to lose objects of cultural and historical value for ever. For example, a significant amount of the rich jazz musical heritage of New Orleans may have been lost during the hurricane Katrina, together with other artifacts that were stored on destructible media.

The need to preserve musical data brings up the question “How has 3D printing impacted the music industry?” To answer this question, it will be helpful to address these topics:

  • What methods have been used historically to store music?
  • What modern methods are now utilized for storing music?
  • How useful is 3D printing for the music industry?

What Methods Have Been Used Historically To Store Music?

The traditional method for storing music relies on writing music on sheets of paper. For example, classical orchestral works by Bach, Mozart, Beethoven and others are available as published sheet music.

This method for storing music cannot provide good longevity and permanence because (a) the medium for storing the music (paper and ink) degrades over time, and (b) the stored music can be easily lost due to fire or floods.

Improvements to storing music utilize an audio format, together with physical recording media.

Over the last 100 years, musical storage relied on the following methods:

  • Prior to the year 1900, audio data in the form of sound waves were transcribed to paper, glass and wax cylinders as mechanical analog signals recorded as lateral grooves. Stylus motion over the grooves was used to render the recorded audio data. Products in this era include the Edison phonograph, the Dictaphone and the phonograph disk.
  • Between 1900 and 1948, improvements to sound recordings utilized magnetization and electrical amplification of analog signals to produce high fidelity audio. Products in this era include the magnetic tape, audio cassettes, and vinyl phonograph discs. Tape speeds ranged from , and discs at.
  • Between 1948 and 1970, significant audio signal processing techniques utilized Dolby noise reduction and stereophonic rendition. Products in this era include the 4-track and 8-track stereo, the compact cassette, the microcassette and the minicassette.
  • After 1970, digital processing technology produced advanced products that utilize audio formats such as MPEG, MLP, and many other audio formats found in products that provide CDs, DVDs, HD DVD, and Blu-ray technology.

What Modern Methods Are Now Utilized For Storing Music?

Because the music library continues to grow at an alarming rate, compression methods have been developed to store voluminous amount of audio data on the cloud, and to make them available to users by using web streaming technology.

Well-known competitors in this audio storage and streaming market place include the following:

  • Apple’s iTunes stores over 43 million songs. The songs can be downloaded on iPhones, iPad, iPod or other Apple-based products. The audio formats are limited to Apple approved formats, but conversion software is available for other formats. The service does not use web streaming.
  • The Amazon Cloud Player provides a service similar to Apple iTunes. However, the Amazon Player utilizes a compression that is lossier than iTunes. Being lossy means that the original music is not rendered with true fidelity. Portions of the audio signal are dropped when rendered in such a way that the human ear cannot easily detect the difference between the true and rendered sound.
  • Google Play Music provides free access to over 30 million songs. Because this service is free, it may be considered a bargain, compared with the other paid services. Both Amazon and Google services utilize web streaming.

How Useful Is 3D Printing For The Music Industry?

An amazing benefit that 3D printing brings is that musical recordings stored in digital format can be recalled and reprinted at will. For sentimental reasons, many people like to play music that was previously available only on phonographs. With 3D printing, both old and modern music can be stored in digital form, to be retrieved and 3D printed on improved durable media. As more sophisticated materials become available for 3D printers, high quality audio recordings can be printed with outstanding audio fidelity and rendition.

Apart from printing musical recordings, 3D printers can print musical instruments such as guitars, drums, pianos and saxophones. The list of musical instruments will grow as more 3D printing materials are discovered.

To summarize, it is reasonable to conclude that 3D printing makes it possible to:

  • Store music digitally and reproduce it faithfully,
  • Print a variety of musical instruments.

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difference between IGES and STEP Files

What is difference between IGES and STEP Files?

What is difference between IGES and STEP Files?

  • Both are "neutral file formats". They were developed to be compatible with different 3D packages
  • The oldest is IGES (Initial Graphics Exchange Specification). It was developed in the mid '70s by the defense industry to solve compatibility issues between different software packages
  • STEP (Standard for the Exchange of Product data) was created in the '80s by ISO as an improvement on IGES
  • The most widespread format is IGES but it can only contain basic 2D or 3D data
  • STEP is more versatile and contains additional information such as material information and tolerances

For most design engineers, the following scenario should look familiar: Peter, the lead designer for company X, needs to send a CAD model to Mary, the design engineer for company Y. Peter designed the part using Solidworks and Mary only works in Pro Engineer. Peter’s Solidworks file can’t be opened in Mary’s software, so the simple transfer of a part file has now become a problem.

This issue of non-interchangeable proprietary file formats for CAD data has been around for decades. Software companies want to promote the use of their own modeling packages, and one way to do this is to ensure that only their package can open a file created in their software. Unfortunately, every major 3D modeling software company has done this, so communicating between them is a problem.

Luckily, a solution exists in the form of neutral file formats. A neutral file format is one that can be passed between different modeling software packages. Bob could use a neutral file format to pass his CAD model to Susan, who could then open it and work with it as needed.

The most common variants of these neutral file formats are the IGES (pronounces eye-jess) and STEP formats. You can recognize these formats because the file name will end in .iges, .igs, .stp, or .step.

The History of Neutral file Formats

In the mid-seventies, the United States government realized that it had a problem. With all of the unique proprietary CAD programs used by its different contractors, millions of dollars and countless hours were wasted on the tedious process of sharing and converting data between all the systems. You can imagine how many times this scenario played out on a large project like an aircraft carrier or missile delivery system with hundreds of suppliers!

So, the Air Force launched a project in conjunction with Boeing and several other large industry partners to create a neutral file format. The result was IGES (Initial Graphics Exchange Specification), which is a flexible file format that codifies drawing, 3d geometry, and other critical CAD data in a format that can be shared between all major CAD systems.

Since the eighties, the US Department of Defense has required that the IGES format be used for all weapons and defense contracts, and it has been adopted in other industries as well.

STEP (Standard for the Exchange of Product data) was created in the eighties as an improvement on the IGES standard by ISO (the International Standards Organization), with the goal of creating a global standard for a range of CAD-related data types. Due to the complexity of the undertaking, it has taken years of development and is still being continuously upgraded. It is currently the largest of all of ISO’s standards.

Difference Between IGES and STEP

IGES is the most widespread standard, and is supported by nearly all major CAD systems worldwide.

An IGES file contains basic CAD information:

  • 2D and 3D geometry (curves, surfaces, and wireframes)
  • Presentation elements (drafting elements like lines and annotations)
  • Electronic and pipe schematic elements
  • Finite element modeling elements
  • Language and product definition data

STEP is a newer standard, and is therefore not as widespread as IGES. However, most major CAD programs recognize STEP and its ubiquity is steadily growing as the standard improves.

STEP files contain the same product definition information as IGES, with the following additions:

  • Topology
  • Tolerances
  • Material properties
  • Other complex product data

Practical Considerations

In most cases where solid models or drawings are being shared, either file format will work fine. For compatibility it is safest to start with IGES, since it is the more common format and therefore more likely to work with the receiving party’s software.

However, a designer should also consider the information being shared. If the file being sent needs to contain more product definition (for example, geometric dimensioning and tolerancing data, material properties, etc), then STEP would be a better choice.

It is not uncommon for one supplier to have trouble working with one format, and to request its alternative. Depending on your industry and software, you will likely become familiar with one or the other and stick to it in most situations

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