基于X射线CT技术快速检测不同含水率状态下的毛竹密度

密度是竹材材性的重要指标之一，与竹材诸多物理力学性质紧密相关，且测定结果因含水率状态不同而不同。基于X射线计算机断层扫描(X-CT)技术，比较了不同竹龄毛竹全干、气干、饱水状态下CT值的差异程度，除4年生和10年生毛竹CT值差异较大以外，其余竹龄CT值差异较小;分别在全干、气干、饱水状态下对所测定的CT值与相应状态下毛竹的密度进行拟合建模，同时还对不同含水率梯度状态下的CT值与密度进行拟合建模，进而系统分析了不同竹龄毛竹在单一含水率状态下和不同含水率梯度状态下CT值与密度之间的关系;对不同竹龄毛竹全干状态下相对竹青径向位置的CT值进行了拟合，依据CT值与密度之间的关系，解释说明了毛竹径向密度因竹龄不同所产生差异的原因。试验结果表明，毛竹全干、气干、饱水密度与相应的CT值之间均存在线性关系，且拟合斜率相近;在所选含水率梯度状态下毛竹密度与CT值之间存在线性关系，且密度与CT值关系受水分影响较小，回归方程为：D=0.001H+1.003 2，R2=0.968 3(D为密度，H为CT值)，验证模型决定系数R2=0.974 3;不同竹龄毛竹全干状态下竹青、竹黄处密度差异较小，而在竹肉处差异较大。这些结果为实现快速检测毛竹在不同含水率状态下的密度提供了技术支持和数据参考，同时X射线计算机断层扫描(X-CT)技术也为深入研究竹材材性和构造提供了一种切实可行的新途径。

Rapidly Detection for Moso Bamboo Density under Different Moisture ConditionBased on X-CT Technology

Density ,which is closely relate with many physical and mechanical properties of bamboo ,is one of the important indi‐cators of bamboo material properties .Moreover ,because of existing different moisture gradients in bamboo ,the measured re‐sults of the density are different .Based on X‐ray computed tomography (X‐CT) technology ,the divergent degree of the CT val‐ues of 7 different aged Moso bamboo was compared under oven‐dried ,air‐dried and water‐saturated conditions .Except for the 4‐year‐old and 10‐year‐old Moso bamboo ,the CT values of other aged bamboos have minor differences with each other ;the models for the measured CT values and the corresponding densities of Moso bamboo were respectively fitted under oven‐dried ,air‐dried and water‐saturated conditions .Meanwhile ,the model was also fitted under different moisture gradients ,which was composed by the measured CT values and the corresponding densities of Moso bamboo .Then the relations between the CT values andthe densitiesof 7 different aged Moso bamboo were systematically analyzed under single moisture content and three moisture gradi‐ents ;the CT values were fitted under oven‐dried condition ,of which the radial positions are relative to the outer of Moso bam‐boo .According to the relation between the CT value and the density ,the fitting curves explain the reasons for the radial density variations of 7 different aged Moso bamboo .Results show that the relations ,which are fitted by the measured densities and the corresponding CT values of 7 different aged Moso bamboo under oven‐dried ,air‐dried and water‐saturated conditions ,are good linear and the slopes of those models are approximate ;the relation of the densities with the CT values for Moso bamboo is linear under different moisture gradients ,moreover ,which is rarely affected by moisture .The regression equation is :D = 0.001 H +1.003 2 ,R2 = 0.968 3(D is the density , H is the CT value) and the determination coefficient of the validation model is :R2 =0.974 3 ;there is no obvious variation between the densities of the inner and the outer ,but not in middle part to 7 different aged Moso bamboo under oven‐dried condition .To realize rapid detection on the densities of Moso bamboo under different moisture content ,these results provide technical support and data reference .At the same time ,X‐ray computed tomography (X‐CT ) technology also puts forward a new feasible way for the further studies of bamboo material properties and structure .