[Image above] The diabolical ironclad beetle is tough—in addition to the ability to play dead and a rough exoskeleton that resembles a rock, this little beetle is hiding some interesting secrets within its exoskeleton that could help design more robust fasteners. Credit:耶稣里维拉;加州大学欧文
这是我们在我们星球上生活的事实，我发现令人惊讶的甲虫占已知动物生命的25％以上，距离地球漫游的所有昆虫的近40％的昆虫。
That’s a lot of beetles. Upwards of 350,000 known species, in fact, exist in nearly all habitats (save marine and polar regions), and they adapted to subsist off of a vast array of different diets.
除了在地球上的生活中适应时，甲虫成功的秘诀似乎是这些昆虫不要灭绝。
虽然所有甲虫在生存方面似乎有点顽固，但有一个特定的甲虫物种，脱颖而出，突出了对完全不同的水平的韧性 - 恶魔般的Ironclad甲虫，Phloeodes diabolicus.
The diabolical ironclad beetle not only plays dead and has a rough textured exoskeleton that blends in with surrounding rocks, but its survival mechanisms also include an exoskeleton that is legendary for being tough. Entomologists know that the beetle’s exoskeleton is so tough that it can bend the steel pins used to mount specimens of insects for display. And the insect can even get up and walk away unharmed after being run over by an automobile—see for yourself below.
但是是什么让这个小甲虫如此恶心？A new studyreveals some of the secrets the beetle stores in its tough exoskeleton, secrets that could develop biomimetic materials and structures to join dissimilar materials in more robust ways.
该团队 - 来自加州大学的国际科学家河畔，加州大学，普瑞丁大学，东京农业和技术大学德克萨斯大学，德克萨斯大学，劳伦斯伯克利国家实验室使用先进的显微镜和光谱，透露a mixture of macrostructure and microstructure elements combine to make the diabolical ironclad beetle’s exoskeleton incredibly strong.
物质说话，它们对甲虫的外骨骼的分析表明，它由富含蛋白质的基质中的对齐的几丁质纤维组成。该基质具有比其他可比较的甲虫更高的蛋白质含量，这是科学家推测的含有恶魔般的Ironclad甲壳物的令人难以置信的能力，以承受其体重39,000倍的势力抵抗粉碎。
The team specifically focused on a part of the insect’s exoskeleton called the elytra, which are two hard, protective blades that armor a beetle’s back to protect a set of more delicate wings used for flying. Elytra act like a protective outer door, opening to allow a beetle’s wings to extend in flight and then closing to protect the delicate structures when not in use. (To be clear, the diabolical ironclad beetle has lost the ability to fly, but it maintains a set of protective elytra.)
Beyond the material composition of the insect’s exoskeleton, the study also shows that macrostructural elements of the elytra also contribute to the beetle’s toughness—namely, a series of lateral support structures along the perimeter of the insect’s body, and a robust suture that holds the two elytra together.
首先，侧向支撑。位于昆虫的身体边缘周围，这些结构在压缩昆虫时，有助于Elytra，防止其体腔被压碎。压力集中在昆虫壳的周边周围，因此这些结构精确地提供了关键的支持，在那里需要大部分。
该团队使用计算机断层扫描对这些结构的分析表明，恶魔般的Ironclad甲虫在其外壳周围包含三种不同类型的支撑结构。
最强大的支持结构，位于昆虫身体的前部附近，具有架构，其在应变下互锁和变硬。这些结构最接近昆虫的内器官，因此互锁结构提供最大的支持，以帮助防止昆虫的胆量在压缩时被压出。
沿着壳体进一步支撑壳体不互锁，而是具有锁定设计，而仍然朝向昆虫壳的背面的支撑是完全独立的并且没有机械连接。
虽然团队表征了三种类型的支持结构，但重要的是要注意这些不同的结构不是不同的元素。相反，它们沿着甲虫外壳的长度无缝地过渡到下一个，创建变量刚度梯度。
This strategy of varying stiffness increases the exoskeleton’s toughness by not simply allowing it to withstand pressure—it also strategically deflects energy away from critical areas, like where the internal organs are located, to other areas of the exoskeleton that can better dissipate energy without catastrophic failure to the beetle.
除了这些差动横向支撑件之外，甲虫的两个ELYTRA也通过坚固的连接缝合在一起，类似于互锁拼图件。该体系结构将ELYTRA绑定在一起，在外骨骼中的关节较弱的位置提供支撑。该结构还包括独特的分层微结构，防止局部应力，另一种方式甲虫战略性地消散能量以抵抗压碎。
“当你打破一个拼图的时候，你希望它在脖子上分开，最薄的部分，”高级作者David Kisailus.在A中说UCI新闻稿。“但我们没有看到这种巨大的悲伤分裂了这种甲虫。相反，它分层，提供了更加优雅的结构失败。“
为了确认这些结构和架构的各种结构和架构占甲壳虫的韧性，kisailus和团队在3D印刷复合材料紧固件中模仿甲虫的Ironclad结构，并在实验室中测试了它们的机械强度。这些测试表明，与商业航空航天紧固件相比，甲虫基结构略微较强但表现出显着增加的能量位移，以避免灾难性失败。
The information from the mechanical tests extends beyond just expanding our knowledge of nature. It can help develop biomimetic strategies that translate into tougher materials design as well as engineering of robust structures. For instance, the scientists note that such information could be used to design more robust strategies to join different materials, which remains an engineering challenge in aerospace applications and beyond.
“These designs could be useful in joining other dissimilar engineering materials such as plastics and metals. Such materials are currently joined by mechanical fastening, which adds weight and introduces stress concentrators that degrade the strength and can lead to fatigue issues, corrosion and early failure,” the authors write in the paper.
They also note that tuning material parameters could further enhance these structures, providing exciting possibilities for robust new strategies to engineer structures as tough as diabolical beetles.
本文发表在Nature， 是 ”Toughening mechanisms of the elytra of the diabolical ironclad beetle“（DOI：10.1038 / S41586-020-2813-8）。