A simple and inexpensive device for assessing the impact damage of grains has been designed and fabricated. The materials for the device are readily available in developing countries, and the device can be fabricated in most workshops. The device has been used to assess the impact damage on bambara groundnuts. It was found that at all grain moisture contents studied, grain damage increased as the grain impact velocity increased. A semi-logarithmic relationship was found to exist between grain damage and grain impact velocity at 10%, 20% and 30% grain moisture contents, while a linear relationship was found at 40% grain moisture content. At all grain impact velocities studied, grain damage decreased linearly with increase in grain moisture content. A semi-logarithmic relationship was found to exist between the rate of decrease in grain damage and grain impact velocity.

Introduction

Mechanical and physical properties of grains are necessary in designing, handling and processing equip- ment for them. The resistance to impact, among other mechanical and physical properties, play a very impor- tant role in the design of threshers, dehaulers, equipment for loading and unloading, storage structures, harvest- ing machines, drying equipment, conveyors, spouting and free-fall dropping equipment. This is because during operations in these equipment, grains are subjected to impact between grains and other metallic, wooden and plastic surfaces which may result in mechanical damage.

Damaged grains perform poorly in storage, are sub- ject to heavy infestation with mould and insects and accumulate free fatty acids (White, Loewer, Ross, & Egli, 1976). As a result, grains are discoloured, germi- nation and seedling vigour are reduced and the grains produce mycotoxins, which lead to mustiness and total decay (Christensen & Kaufmann, 1974; Cooke & Dickens, 1971).