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.

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 July 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 July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
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:
from the past week

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