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Posts Tagged ‘composites’

Using Simulation for Accurately Modeling Fiber-Reinforced Composites

Monday, May 6th, 2013

Designing lighter products, whether they’re as large as jet liners or as small as mobile phones, has always been smart business. Less material means less cost and lower energy consumption, both in production and operation. Lower production costs mean higher profit margins for manufacturers. Lower operational costs lead to broader customer acceptance and higher market share.

These days, the “smart business” in lighter products has been upgraded to “essential ingredient.” Lower weight and material efficiency are mandatory for companies that expect to succeed in markets coping with volatile energy prices and increasing environmental regulations. Higher energy prices cause sharp swings in production costs. Manufacturing a product and its component materials means more predictable costs and higher profit margins.

End products are also subject to more scrutiny during their operational lives. Vehicles have to squeeze more miles out of every gallon to satisfy mandates such as U.S. corporate average fuel economy (CAFE) standards

 

For decades, making a product lighter meant optimizing designs to cut out mass that wasn’t needed to achieve engineering goals. Now, extensive use of fiber-reinforced composites has introduced a new weight-saving measure into product design. Especially in vehicle design but also in appliances and industrial machinery, composites offer comparable strength to metal at a fraction of the weight.

However, introducing composites into product design requires extensive testing. Composites’ plasticity means they do not perform as predictably as metals under real-world conditions. Many manufacturers qualify composites through extensive physical testing on prototypes. This is expensive, time consuming, and can be replaced by simulation – provided that simulation evolves to accommodate composites. Otherwise, they will not yield accurate material allowables, and inaccurate allowables can lead to poor product performance or outright failure.

Simulation technology has traditionally focused on metals. Composites, however, have different properties from metals. For example, a metal-stamped part will behave the same way regardless of how it is manufactured. By contrast, the manufacturing process can change a fiber-reinforced plastic part’s behavior significantly because the process can affect the orientation of the fibers in the material’s epoxy-resin matrix.

Those additional variables complicate engineers’ tasks. They can optimize a design for maximum lightness but end up with a different set of problems because the composite won’t perform the way they expected. Engineers must be able to simulate the strength of composites in different configurations and through various manufacturing processes down to the microstructure level. However, simulation technology hasn’t accommodated them so far.

Most simulation solutions depict composites as “black aluminum.” They represent a composite part’s geometry, but not the full range of its properties. Composite suppliers provide their customers with property data, but that data seldom takes into account the manufacturing process’ influence on the material. Entered into a simulation, these data points will not produce accurate results.

Without accurate material modeling and simulation, designers have to approximate how the composite will perform under real-world conditions. That often leads to over-designing to guard against failure. Over-designing undermines the purpose of designing with plastic or composite in the first place – using less material and reducing weight. It also adds unnecessary cost.

Many simulation technology vendors have incorporated some level of non-uniform material behavior into their solutions. However, these solutions only simulate composite behavior on the surface. A truly realistic model requires an intelligent handle on:

  • individual properties of the fiber and the matrix;
  • the composition of the overall materials; and
  • manufacturing processes’ influence.

Conventional simulation tools do an excellent job of modeling a party’s geometry, loading, deformation physics, etc.  Incorporating detailed material behavior for composites drives further precision into the simulation lifecycle.

Giving engineers that precision opens a new range of possibilities for making products lighter without sacrificing performance. For example, an automotive OEM wants to re-design a metal engine mount in composite to save weight. Design engineers develop the basic geometry for the new mount in a 3D CAD environment. The mount weighs 1.2 kilograms. Simulation reveals that the engine mount performs its function under normal loads and in normal operating conditions.

Through virtual simulations to analyze the composite’s behavior in that shape and function, the design team does a series of iterations, analyzes the mount’s performance, and reduces its mass by 40 percent without compromising performance. The lower mass shaves 15 percent from the mount’s cost.

This is what design teams can achieve when they have the tools to model and simulate composites with the same precision they have for simulating metals. It’s the approach that manufacturers need to incorporate in bringing composites into their designs while keeping prototyping costs. The result will be lower material use and energy consumption in production and operation, and more accurate material and part performance. These essential qualities will enable manufacturers to meet the new economic realities of rising energy costs and the societal obligations of sustainability through lighter, better products.

This article was contributed by Dr. Roger Assaker, PhD,  founder and CEO of e-Xstream Engineering, and also chief material strategist at MSC Software. Please see http://www.mscsoftware.com/product/digimat for more information.)

Autodesk Acquires Firehole Composites, Extending Its Analysis Software Portfolio

Wednesday, March 20th, 2013

Not just resting on its cash reserves or other recent acquisitions, Autodesk announced that it has completed the acquisition of Firehole Technologies (DBA Firehole Composites), a privately held company that specializes in design and analysis software for composite materials. Through this acquisition, Autodesk will expand its analysis software portfolio to work with light, strong, and complex composite materials. Firehole Composites is based in Laramie, Wyoming, also the home of the University of Wyoming, and a town with an incredibly low unemployment rate of 3.4%.

“As manufacturers move to more complex material such as light weight composites, new simulation technology is required to predict and optimize the performance of these materials. This acquisition will enable Autodesk to deliver this technology to a broad spectrum of design and engineering industries,” said Buzz Kross, senior vice president for Design, Lifecycle and Simulation products. “The Firehole team will add significant expertise in next generation materials and non-linear analysis, as well as industry-leading technologies that strongly complement our solutions for structural, thermal and plastics analysis.”

Engineered composites are complex materials made from two or more  materials with widely different physical and/or chemical properties. When combined, the constituents produce a material with characteristics much different than the individual components. Interestingly, though, (and this adds to the mystique behind composites), the individual components remain separate and distinct within the finished structure. Even though it’s been around a long time, today, still the most common composite material is concrete. Because composites are complex materials, simulating and analyzing them and their behavior is a very computationally demanding proposition.

Check out the video for CompositePro for FEA that demonstrates some of the tools availble to support composite finite element analysis process. Among other things, CompositePro can be used to:

  • Determine ply-level or laminate-level material properties for 2D shell or 3D solid element analyses
  • Investigate complex failure modes of stuctures such as tubes or sandwich panels to understand when they will fail

Autodesk says it intends to sell and support the existing Firehole Composites product line, as well as integrating the composites analysis technology more tightly with Autodesk products. No surprise there, especially the latter. As usual, and not unexpectedly, terms of the transaction were not disclosed.

SpaceX Cuts Composite Development Time With Siemens’ Fibersim

Friday, June 1st, 2012

The privately funded and developed SpaceX Dragon just returned from a flight that was successful from start to finish. The SpaceX Dragon capsule parachuted into the Pacific on May 31, 2012 to conclude the first private delivery to the International Space Station and ring in a new era for NASA’s approach to space exploration.

SpaceX’s CEO/CTO, Elon Musk, said “Welcome home, baby,” and was said to be a bit surprised with the SpaceX Dragon’s triumphant mission.

After its initial success, the primary goal for SpaceX will be to repeat the success on future flights.

Because the unmanned supply ship’s arrival was so accurate, when it splashed down, a fleet of recovery ships was able to quickly move in to pull the capsule aboard a barge for towing to Los Angeles.

It was the first time since the shuttles stopped flying last summer that NASA got a sizable load returned from the space station – more than half a ton of experiments and equipment.

The arrival of the world’s first commercial cargo carrier concluded a nine-day test flight that was virtually flawless, beginning with the May 22, 2012 launch aboard the SpaceX company’s Falcon 9 rocket from Cape Canaveral, continuing with the space station docking three days later, and departure six hours before landing in the ocean.

SpaceX attributes a large part of its design and engineering success to CAD, CAM, and CAE software, including Fibersim from Siemens PLM Software for composite material design and engineering.

According to Chris Thompson, Vice President of Structures Engineering at SpaceX, “Time is always of the essence for us, so Fibersim’s proven ability to take us from art to part so rapidly was a critical consideration in our decision to purchase the software. Fibersim improves product quality by providing accurate engineering information to the manufacturing floor, which also helps the repeatability of the manufacturing process.” The repeatability of the manufacturing process is vital for repeated success of the space platform.

 

Adopting Advanced Composite Materials

For more than 50 years, commercial access to space has been limited by the high cost of flight operations. However, Space Exploration Technologies Corp. (SpaceX) has rewritten the rules of the game by adopting a new business model and cutting edge technologies to enhance reliability and reduce the cost of space access.

One significant way SpaceX enhanced the performance of its Falcon rocket and Dragon capsule was by adopting composite materials. Composites have received growing acceptance in a variety of industries, including aerospace, and the space industry has taken note. SpaceX was no exception. The design team recognized that composites could significantly enhance performance by improving the strength-to-weight ratio of the materials used to construct its spacecraft.

Once that decision was made, SpaceX conducted an evaluation of available composites engineering solutions and concluded that Siemens PLM Software’s Fibersim software was the best fit for its design and manufacturing environment.

“Based on our comparison, there was no question that Fibersim was definitely the best choice on the market for designing and manufacturing composite components to suit our needs,” said Kirk Matthes, SpaceX’s design manager.

SpaceX’s business model is derived from the philosophy that simplicity, so low-cost and reliability can go hand in hand. By eliminating the traditional layers of management and subcontractors, the company reduced costs while speeding decision making and delivery. Likewise, by keeping the vast majority of manufacturing in-house, SpaceX reduced costs, kept tighter control of quality, and ensured a tight feedback loop between the design and manufacturing teams. By concentrating on simple, proven designs with a primary focus on reliability, the company has reduced the costs associated with complex systems operating at the margin. Fibersim has proven very valuable within that design/engineering paradigm.

SpaceX used Fibersim to design and manufacture a variety of composite parts on both the Falcon rocket and the Dragon capsule. Fibersim was used to develop production fiber placement diagrams and laser projection files. It was also used to assist with actual fiber placement for the spacecraft’s thermal protection system, including the heat shield, exterior panels, insulating layers on the rocket and spacecraft, and several panels around the nose cone and engines.

Fibersim is now being employed from the outset on all new composites projects and has enabled SpaceX to reduce the design-to-manufacturing time on composite parts, such as the 5-meter fairing boattail panel by 71 percent, from seven days to two days. For other designs, the generation of manufacturing data was reduced by as much as 86 percent, from seven days to one day, using Fibersim. These time savings mean that changes are processed more quickly, designs are updated more reliably, and the overall process flows more smoothly.

SpaceX has used Fibersim to perform a variety of tasks, including creating designs, making flat patterns, working in conjunction with its finite element analysis (FEA) software, and creating laser data.

 

Strong Support From Siemens

As a newcomer to composites, SpaceX was also concerned about finding a software vendor that had significant composites experience so it could receive the necessary guidance and support as it embarked on working with new materials.

“Siemens PLM Software’s support is excellent,” said Matthes. “Anytime we have a problem, we can send a model to the Siemens PLM Software’s technical consultant and he helps us get through the issue. Again, as a fast-paced organization, we must continually be moving forward, and Siemens PLM Software’s responsiveness and expertise enables us to do just that.”

Siemens PLM Software also embeds the know-how derived from its years of experience in the composites industry to provide intuitive, easy-to-use features for the design of a variety of composite structures. This is integrated into the software, speeds learning time, and makes the learning experience for new users more effective. This also aids in training new users who may not have experience in designing with composite materials.

Since most of the composite parts are not especially complicated, the Fibersim Composites Engineering Environment (CEE) has proven to be sufficient. However, certain sections of the launch vehicle are characterized by complex curvature, so SpaceX opted for Siemens PLM Software’s Advanced Composites Engineering Environment (ACEE) to design those parts. ACEE exploits the inherent advantages of many different composite design methodologies –including structure-based, zone-based, and ply-based design — to enable efficient engineering of large, complex structural components and highly contoured composite skins.

Most importantly, it helps to address the changes that inevitably occur while developing a composite structure. Based upon inputs from analysis, manufacturing or further iterations of the design, the definition evolves to its final state. This can require frequent updates and changes, which are time-consuming without software created specifically for this process. ACEE is designed to meet this challenge and create a more straightforward process for managing design changes.

“ACEE provided a significant boost to our efforts to define or import laminate specifications and requirements quickly using a zone-based design methodology,” explained Matthes. “It helped speed ply definition by dynamically generating zone transitions and ply boundaries using an offset profile.”

The ability to accelerate the process and make it more accurate enables SpaceX to proceed with high speed and quality, as well set new standards for designing and manufacturing composite spacecraft both now and in the future.

As a kid who grew up during NASA’s heyday in the 60s and 70s and the more recent hiatus, I’m now very encouraged about the future of space exploration – due in large part to private enterprise — and I applaud the efforts of SpaceX. I hope SpaceX’s accomplishment ushers in a new wave of engineers, scientists, and entrepreneurial companies who will take advantage of this great opportunity.

 

SolidCAM: Program your CNCs directly inside your existing CAD system.



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