在采矿、水利、岩土等研究领域内，相似材料模拟是一种很重要的实验方法。而在采矿工程中，相似材料模拟的往往是层状模型，岩层的弯曲变形和断裂破坏是关键问题。为最大限度地保证岩层抗弯强度和断裂强度的相似性，相似材料抗拉强度的测定尤为必要。相似材料的抗压、抗剪强度的测量方法比较简单。但是，抗拉强度的测定一直是一个难点。对于以铁粉或磁铁粉为骨料的相似材料，其中的铁或磁铁粉颗粒在非均匀磁场中要受磁场力的作用。本文用亥姆霍兹线圈构建了一个均匀梯度磁场，将用含铁相似材料制成的圆柱形试件放入其中，并采用ANSYS有限元程序进行了数值模拟。通过对所构建的实验模型采用控制变量法，研究了不同结构的亥姆霍兹线圈、不同试件密度、不同线圈安匝数等条件下试件所受的电磁力的情况。得出了电磁力随线圈结构、安匝数和试件密度的变化规律。在此基础上，提出了一种新的拉应力加载方法，并对该方法的应用前景进行了展望。

Similar materials simulation is a very important experimental method in the mining, irrigation works, geotechnical studies and other fields. In mining engineering, strata models are often simulated by similar material simulation model, rock bending deformation and fracture damage is the serious problem. To ensure comparability of breaking strength and distortion strength. The tests for similar material tensile strength are quite necessary. The measurement methods for compressive strength, sheared intensity of similar material are relatively simple. However, the measurement for tensile strength is always a difficulty. For the similar materials which iron or magnetite powder is adopted as aggregate to increase bulk density, the magnetic field strength will be imposed on the iron or magnetite powder particles when they are in a non-homogeneous magnetic field. We have designed a uniform gradient magnetic field with Helmholtz coils. putting the cylindrical sample in the field, and numerical simulate with ansys FEM, we have studied the electromagnetic force which the sample beared in different Helmholtz coil for different densities samples, different Ampere-turns et al by controlling variable in the established experimental model. And obtained the law of the magnetic force changed with the structure of the Helmholtz coils, densities of the samples and Ampere-turns et al. Basis on our studies, we proposed a new method of pulling stress, and prospect the application of this new method.