Featured Research

from universities, journals, and other organizations

Bone-Shaped Fibers Increase Strength Of Composite Materials

Date:
January 18, 1999
Source:
Los Alamos National Lab
Summary:
Researchers at the Department of Energy's Los Alamos National Laboratory have shown that enlarging the ends of short fibers used in composite materials simultaneously increases the overall toughness and strength of the material. Composite materials are used widely in the automotive, aerospace, civil engineering and other industries requiring lightweight but structurally sturdy parts.

Researchers at the Department of Energy's Los Alamos National Laboratory have shown that enlarging the ends of short fibers used in composite materials simultaneously increases the overall toughness and strength of the material.

Related Articles


Composite materials are used widely in the automotive, aerospace, civil engineering and other industries requiring lightweight but structurally sturdy parts.

The Los Alamos finding impacts a problem material scientists have been trying to solve for decades: how to get effective load transfer between fibers and the surrounding matrix without making the composite more brittle, as happens when the fibers are tightly bonded to the matrix.

The special fibers, shaped like a cartoon dog bone, anchor into the matrix at each end because of their shape but bond only weakly with the matrix along their length. This allows the fibers to help carry the load. The experimenters designed the shape and size of the enlarged fiber ends so they don't experience the stresses that usually snap fibers and limit a short-fiber composite's performance.

"People have been trying to solve this problem for the last couple of decades," said Los Alamos' Yuntian Zhu, who leads the research effort. "We've shown that this fairly simple mechanical approach can provide a solution."

In a pair of scientific papers, Zhu and his colleagues in Los Alamos' Material Sciences and Technology Division described their experiment of developing bone-shaped fibers from commercially available polyethylene stock and mixing them in a polyester matrix. They made another composite from the same materials, but without enlarging the ends of the fibers.

Standard, straight fibers can pull free of the matrix material if the fibers bond weakly with the surrounding matrix. If, on the other hand, the fibers bond strongly with the matrix, they can snap under the high stresses generated by a crack in the matrix.

The bone-shaped fibers connect mechanically with the matrix predominantly at their ends. They have a weak interface, and so don't

experience extreme stress, but remain anchored at their ends and so still help carry the load felt by the composite.

The composites developed for the experiment were subjected to forces to the point of failure and examined microscopically.

The composite with the bone-shaped fibers significantly outperformed the straight-fiber composite for both toughness and strength (toughness measures the amount of energy required to damage the composite; strength measures the composite's resistance to pressure, or force spread over a given area).

The bone-shaped fiber composite was much more resistant to the propagation of cracks; the fibers would actually bridge the crack, refusing to let go. Inspection showed that even though a crack in the matrix had snaked through the sample, the sample remained intact overall.

The researchers are conducting additional experiments to adjust the shape of the fibers for optimal composite performance. One member of the team, Irene Beyerlein, is using computer modeling to better understand the experimental results and predict the outcome when the researchers use different materials or change the fiber design.

Composite makers have successfully used long, continuous fibers to increase strength and toughness, but these materials require special, more expensive manufacturing techniques. Short-fiber composites have been long preferred because they are compatible with standard manufacturing processes.

The Los Alamos team expects their bone-shaped fiber approach could also be used in reinforced concrete structures, such as roads, bridges and buildings.

One Los Alamos research paper on this topic is in press at Scripta Materialia; a second paper has been submitted to Acta Materialia.

Other Los Alamos staff members engaged in the research are James Valdez, Michael Stout, Shujia Zhou and Terry Lowe.

Los Alamos National Laboratory is operated by the University of California for the U.S. Department of Energy.


Story Source:

The above story is based on materials provided by Los Alamos National Lab. Note: Materials may be edited for content and length.


Cite This Page:

Los Alamos National Lab. "Bone-Shaped Fibers Increase Strength Of Composite Materials." ScienceDaily. ScienceDaily, 18 January 1999. <www.sciencedaily.com/releases/1999/01/990118081445.htm>.
Los Alamos National Lab. (1999, January 18). Bone-Shaped Fibers Increase Strength Of Composite Materials. ScienceDaily. Retrieved November 25, 2014 from www.sciencedaily.com/releases/1999/01/990118081445.htm
Los Alamos National Lab. "Bone-Shaped Fibers Increase Strength Of Composite Materials." ScienceDaily. www.sciencedaily.com/releases/1999/01/990118081445.htm (accessed November 25, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Tuesday, November 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Who Will Failed Nuclear Talks Hurt Most?

Who Will Failed Nuclear Talks Hurt Most?

Reuters - Business Video Online (Nov. 25, 2014) With no immediate prospect of sanctions relief for Iran, and no solid progress in negotiations with the West over the country's nuclear programme, Ciara Lee asks why talks have still not produced results and what a resolution would mean for both parties. Video provided by Reuters
Powered by NewsLook.com
Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Flying Enthusiast Converts Real-Life Aircraft Cockpit Into Simulator

Reuters - Innovations Video Online (Nov. 25, 2014) A virtual flying enthusiast converts parts of a written-off Airbus aircraft into a working flight simulator in his northern Slovenian home. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Car Park Solution for Flexible Green Energy

Car Park Solution for Flexible Green Energy

Reuters - Innovations Video Online (Nov. 24, 2014) A British solar power start-up says that by covering millions of existing car park spaces around the UK with flexible solar panels, the country's power problems could be solved. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Microsoft Adds Robot Guards, Ushers In Sci-Fi Apocalypse

Newsy (Nov. 23, 2014) Microsoft has robotic security guards working at its Silicon Valley Campus. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins