Material properties of manatee rib bone
Material properties of manatee rib bone
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DOI：
10.1111/j.1469-7998.2007.00366.x
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发表时间：
2008-02-01
影响因子：
2
通讯作者：
Reep, R. L.
中科院分区：
文献类型：
--
作者：
Clifton, K. B.;Yan, J.;Reep, R. L.
从1974年到2006年，佛罗里达海牛（trichecchus manatus latirostris）与水路相关的死亡率占所有死亡人数的24%。其中，撞击造成的死亡占所有船舶死亡人数的66%。为了建立保护海牛的安全船速，需要对海牛骨骼的材料特性进行估计，以量化船只撞击对海牛的生物力学影响。海牛肋骨的独特之处在于它们是厚骨赘生物。对肋骨加工后的试件进行三点弯曲试验。按性别测定了三种尺寸等级的强度、模量、断裂功和断裂韧性。平均抗弯强度为62 ~ 160 MPa，弹性模量为4 ~ 18 GPa，断裂功为3 ~ 6 MJ m（-3）。断口分析计算韧性，平均为1.4-2.9 MPa m（1/2）。结果表明，海牛骨骼材料的强度和韧性不如其他哺乳动物骨骼。尽管随着动物的成长，骨骼的静态强度会增加，但它不能吸收更多的能量。事实上，在身长超过265厘米的动物中，吸收冲击能量的能力似乎随着体型的增加而下降。这种下降部分是由于骨骼的高密度和矿物质含量。矿物含量随大小变化不大，这表明材料特性可能与骨骼数量有关。在机械变量方面，男女之间没有差异。骨头的厚骨性使海牛能够很好地适应环境，但也使它极易受到船只的致命伤害。
Watercraft-related mortality of the Florida manatee Trichechus manatus latirostris accounts for 24% of all deaths from 1974 to 2006. Of these, the proportion of deaths due to impact accounts for 66% of all watercraft fatalities. To establish safe boat speeds for manatee protection, an estimate of the material properties of their bone is needed to quantify the biomechanical effects of boat strikes on manatees. Manatee ribs are unique in that they are pachyostotic. Machined specimens from ribs were tested in three point flexure. Strength, modulus, work of fracture and fracture toughness were determined for three size classes, by sex. The mean flexural strength ranged from 62 to 160 MPa, elastic modulus from 4 to 18 GPa and work of fracture from 3 to 6 MJ m(-3). Fractographic analysis was used to calculate toughness, which averaged 1.4-2.9 MPa m(1/2). The results show that manatee bone material is less strong and tough than other mammalian bone. Although the bone increases in static strength as the animals grow, it is not able to absorb more energy. In fact, the ability to absorb impact energy appears to decline with increasing size in animals over 265 cm body length. This decline is due in part to the bone's high density and mineral content. There was little change in mineral content with size, suggesting that material properties are likely correlated with bone quantity. There were no differences in mechanical variables between the sexes. The pachyostotic nature of the bone, which makes the manatee well adapted to its environment, also leaves it highly susceptible to fatal injuries from boats.