Which characteristic is vital for materials used in assembly?

Strength and durability are crucial characteristics for materials used in assembly because they directly impact the longevity and structural integrity of the assembled products. When designing anything from machinery to furniture, the materials selected must withstand various forces, loads, and environmental conditions. If the materials fail to exhibit sufficient strength and durability, the overall performance and safety of the finished product can be compromised. This is particularly important in applications where safety is paramount, such as in aerospace and construction, where material failure could lead to catastrophic consequences.

In contrast, while factors like cost, aesthetic value, and design complexity may contribute to the overall decision-making process in material selection, they do not fundamentally ensure that an assembly can function effectively or reliably over time. Hence, strength and durability stand out as the top priorities when selecting materials for assembly purposes.