Long creep-recovery behavior of bamboo-based products

Author

• Xinxin Ma
  • 1
• Sheldon Q. Shi
  • 2
• Ge Wang
  • 1
• Benhua Fei
  • 1
  Email author
• Zehui Jiang
  • 1
  Email author
1. 1.Key Laboratory of Bamboo and Rattan Science and Technology of the State Forestry Administration, Department of BiomaterialsInternational center for Bamboo and RattanBeijingChina
2. 2.Department of Mechanical and Energy EngineeringUniversity of North TexasDentonUSA
Original Article

First Online: 26 December 2017

Abstract

This paper describes the bending creep behavior of two types of bamboo-based products, bamboo-laminated veneer lumber (BLVL), and glued-laminated bamboo (GLB, also called Bamboo Glulam) at different stress levels for half a year and recovery for the same time. It was found that the stress level of BLVL was more sensitive on creep property than that of GLB; the creep resistance of GLB was worse than that of BLVL in the stress levels of 30–50%; the instantaneous recovery ratio (elastic recovery to elastic creep) decreased with an increase of the stress levels, while the residual ratio (residual deformation corresponded to the total creep deflections) increased with an increase of stress levels for all specimens; Burgers model fit creep data very well for both bamboo-based products, while the recovery Weibull equation does not fit recovery data well for GLB.

Acknowledgments

This work was supported by The International Centre for Bamboo and Rattan, China, and was funded by China’s “13th Five-Year Plan” to support science and technology project, Grant No. 2016YFD0600900.

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Copyright information
© The Japan Wood Research Society 2017

For further details log on website :
https://link.springer.com/article/10.1007/s10086-017-1683-7

Investigation of elastic constants and ultimate strengths of Korean pine from compression and tension tests

Author

• Na Yang
  • 1
  Email author
• Lei Zhang
  • 2

1. 1.School of Civil EngineeringBeijing Jiaotong UniversityBeijingChina
2. 2.Department of Civil and Environmental EngineeringUniversity of AlbertaEdmontonCanada

Original Article

First Online: 18 December 2017

Abstract

Korean pine (Pinus koraiensis) is a wood species recently adopted in China for the rehabilitation of traditional timber buildings. This paper investigates its mechanical properties with laboratory tests on typical specimens to obtain the moduli of elasticity, Poisson’s ratios, shear moduli, coefficients of mutual influence, crushing strengths and tension strengths in various directions. Highly different failure patterns of specimens in compression test were observed when loaded in different directions relative to the grain while only brittle failure mode was observed for tension specimens. The measured parameters of Korean pine were compared with those obtained from theory of orthotropic elasticity, the empirical formula and the Norris failure criterion, good agreements were reached for all examinations in general which indicate it is admissible to treat Korean pine as ideal orthotropic material.

Acknowledgements

The study presented in this paper was supported by National Natural Science Foundation of China for Excellent Young Scholars (NSFC 51422801), Beijing Natural Science Foundation of China (Key Program 8151003), National Natural Science Foundation of China (Key Program NSFC 51338001), National Natural Science Foundation of China (General Program NSFC 51178028) and National Key Technology R&D Program (2015BAK01B02). The comments from Prof. S.S. Law and his help in polishing the English usage of this paper are also acknowledged.

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Copyright information
© The Japan Wood Research Society 2017

For further details log on website :
https://link.springer.com/article/10.1007/s10086-017-1671-y

Beetles of Kinabalu Park

Author
By Murphy

Kinabalu Park is the first World Natural Heritage Site of Malaysia due to its biodiversity. No doubt you could find many interesting (even the weird ones) insects everywhere. Like the beetle below, I found it rested on a shrub near the Botanical Garden.

This beautiful beetle has metallic-like case, and its shell also looks like body armour. Some beetles bite and some release unpleasant odour. This one played death when I put it on my palm.

Kinabalu Park is a paradise for specimen collectors and entomologists. However, you will be fined heavily for taking anything from the park. Recently a tourist was compounded RM1,000 (about USD330) for plucking plants.

The beetle below was also found near Kinabalu Park. It has a very soft wing cases that feel like leather cushion.

More beetle… In fact, there are less bugs at the foothill of Mt. Kinabalu today. Because of global warming, many bugs have migrated to higher altitude.

Last year I kept complaining about the non-stop rainy poor weather, but now the weather is too hot and dry after Chinese New Year. A minute under the burning sunlight and I already can feel smoke coming out of me. Dry season is supposed to be great for travelling, but the photogenic bugs are all gone hiding.. My blog has been quiet for a long time coz I am busy transferring my files from old laptop to my new PC, and I haven’t gotten a copy of Photoshop installed yet. I was using free graphic editor. It is less user-friendly and contains bugs, but can get the job done.

Photos taken in Kinabalu Park, Sabah Malaysia

For further information log on website :
http://www.mysabah.com/wordpress/beetles-of-kinabalu-park/