Describing how a material behaves when you pull it. Two related uses.

Describing how a material behaves用來形容一種材料的表現 when you pull it.當你去拉它的時候。Two related uses.有兩個相關的用法。

First, and much the commonest, in the fixed phrase tensile strength: how much pulling a material can take before it snaps. Steel has high tensile strength; a piece of paper has very little. Engineers and scientists use this constantly, and it is a measurable number, not a feeling.

First, and much the commonest,第一個，也是遠遠最常見的， in the fixed phrase tensile strength:是在固定片語 tensile strength（抗拉強度）裡： how much pulling a material can take before it snaps.指一種材料在斷裂之前能承受多少拉力。Steel has high tensile strength;鋼鐵的抗拉強度很高； a piece of paper has very little.一張紙的抗拉強度則很低。Engineers and scientists use this constantly,工程師和科學家經常用到這個詞， and it is a measurable number,而且它是一個可以測量出來的數字， not a feeling.不是一種感覺。

Second, on its own, tensile can describe something that can be stretched out without breaking — a tensile metal, a tensile fibre. The word is technical. You will find it in engineering, physics, materials science and product descriptions, almost never in conversation.

Second, on its own,第二個用法，是它單獨使用時， tensile can describe something that can be stretched out without breakingtensile 可以形容某樣東西能被拉長而不斷裂── — a tensile metal, a tensile fibre.像 a tensile metal（可延展的金屬）、a tensile fibre（可延展的纖維）。The word is technical.這是個專業用字。You will find it in engineering, physics, materials science and product descriptions,你會在工程學、物理學、材料科學和產品說明裡看到它， almost never in conversation.但幾乎不會出現在對話裡。

Here is the useful thing behind it: pulling and pushing are different, and materials handle them differently. Tensile force pulls apart; the opposite, compressive force, squeezes together. Concrete is famously strong in compression and weak in tension, which is exactly why builders put steel bars inside it — the steel takes the pulling, the concrete takes the pushing. Once you see that pair, a lot of engineering writing opens up.

Here is the useful thing behind it:這個字背後有個有用的概念： pulling and pushing are different,拉和推是不一樣的， and materials handle them differently.材料應付這兩者的方式也不一樣。Tensile force pulls apart;tensile force（張力）是往外拉開； the opposite, compressive force, squeezes together.相反的 compressive force（壓力）則是往內擠壓。Concrete is famously strong in compression and weak in tension,混凝土在抗壓方面出了名地強，但在抗張方面很弱， which is exactly why builders put steel bars inside it這正是為什麼建築工人會在裡面放鋼筋的原因── — the steel takes the pulling,鋼筋負責承受拉力， the concrete takes the pushing.混凝土負責承受壓力。Once you see that pair,一旦你看懂這一對概念， a lot of engineering writing opens up.很多工程學的文章就會豁然開朗。