Combat Vehicle Weight Reduction by Materials Substitution Proceedings of a Workshop (2018) / Chapter Skim
Currently Skimming:
Topic 3: System Effects and Testing
Topic 3: System Effects and Testing
Pages 29-40
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 29... ...
Later developments included the first composite fan blade in airline service, the 120,000+ thrust engine, modular power tile, and, most recently, ceramic matrix composite production components. He said that since approximately 2004 there have been a number of new material and process introductions for jet engine manufacturing, including the following: 29
|
From page 30... ...
Peretti said that the introduction of new materials can take many years. For instance, modifying an existing material for a noncritical component can take ap proximately 2 to 3 years, but modifying an existing material for a critical structural component can take 4 to 6 years.
|
From page 31... ...
Another example he provided was a bracket. Using additive manufacturing, a group was able to redesign it with an 80 percent weight reduction via topological optimization.
|
From page 32... ...
de Weck spoke about a unique aircraft redesign challenge and the issues affecting vehicle development and how these examples could be used to develop management models for advanced development.2 De Weck discussed the experience that Switzerland has had with its F/A-18 Hornet fighters.
|
From page 33... ...
During the first step, designers conduct parametric modeling of mass, deter mine the key performance requirements, map how requirements impact system mass, and then create parametric scaling relationships. De Weck said that these can either be first-order, physics-based models or empirical models based on historical data.
|
From page 34... ...
He said that typical guidelines are to establish the SRR3 mass plus a 30 percent margin. For preliminary design review, the goal should be to keep 20 percent mass margin, said de Weck.
|
From page 35... ...
Ledo described a case study concerning the Space Shuttle's external tank. The external tank provided the structural backbone for the launch vehicle and had to support the 2.9 million pounds of thrust exerted by each of the two solid rocket boosters, as well as the 1.1 million pounds of thrust exerted by the engines in the tail of the Space Shuttle Orbiter.
|
From page 36... ...
According to Ledo, there were a number of key lessons learned with the devel opment of the Super Light Weight Tank. These included the following: • Industry experts should be engaged early in the design verification cycle; • Verification program should be test-based and failure-mode specific; • Testing to design capabilities is critical to understand margins; • Tests should be performed incrementally to reduce program risk; • Protoflight tests can be used when ultimate load tests are not practical; • Independent analyses can be used to extend test-based data for similarity verification; 4 Variable Polarity Plasma Arc (VPPA)
|
From page 37... ...
These include the au tomotive industry, where friction stir welding could be applied to dissimilar metals. Other markets include titanium ship structures, heat exchangers for power genera tion and liquid natural gas cryogenic storage tanks, and combat vehicles, he added.
|
From page 38... ...
They are produced by selectively e tching out the A element from a MAX phase, which has the general formula Mn+1AXn, where M is an early transition metal, A is an element from group IIIA or IVA of the periodic table, X is C and/or N, and n = 1, 2, or 3. MAX phases have a ayered hexagonal structure with P63/mmc symmetry, where M l 6 B
|
From page 39... ...
. First described in 2011,7 Barsoum explained that MXenes combine metallic conductivity of transition metal carbides and hydrophilic nature because of their hydroxyl or oxygen terminated surfaces.
|
From page 40... ...
So far, it has proven to be a better electrical and thermal conductor than titanium, stated Barsoum. It has also shown strong elastic properties.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.