balance retalionship of forces是什么意思

用法例句

The force distribution of a two-dimensional hexagonal packing granular system of rigid,frictionless,spherical grains is studied under a vertical downward point force on a single grain at the top layer.

研究了二维无摩擦的六角密排结构的球形颗粒系统在顶层单个外力作用下力的分布。