压缩率对杉木心材回复率及力学性质的影响OA北大核心

With a target compression ratio of 40%～65%,the compression deformation in the heartwood of Chinese fir was stabilized through heat treatment using a steam-air mixed medium with pressure.The effect of the compression ratio on wood density distribution,set recovery,and mechanical properties were studied.The results showed that both early wood and late wood were compressed at compression ratio of 40%.As the compression ratio increased,the wood's density also increased,while the internal density distribution became more consistent.With the heat treatment of steam-air at medium pressure,the hygroscopic/water absorption set recovery of Chinese fir at different compression ratios were reduced to 0%～0.63%.Under conditions including air-dried,high-humidity,and water absorption,there was almost no recovery occurred.With the increased compression ratio and density,the wood's hardness,bending strength(MOR,MOE),and compression strength perpendicular to grain continuously increased.There was a highly significant quadratic functional relationship between wood density and hardness.Meanwhile,there were extremely significant linear relationship between wood density and MOR,MOE,as well as compression strength perpendicular to grain,with the correlation coefficient being greater than 0.938.During radial loading under compression perpendicular to grain,typical stress-strain characteristics were not observed.At a compression ratio of 40%,the compressive strength perpendicular to grain under tangential loading increased by approximately 50%,however there was almost no increase under radial loading.When the compression ratio reached at least 45%,the compressive strength perpendicular to grain under both tangential and radial loading were almost the same.At a compression ratio of 65%,the compressive strength perpendicular to grain under both tangential and radial loading reached four times more than those of the control wood.