中文摘要：

运用合成展开法和微分不等式理论研究了一类四阶方程的奇摄动边值问题.先运用合成展开法,构造了问题的形式渐近解,再运用微分不等式理论证明了原问题解的存在性及所得形式渐近解的一致有效性.最后用一个例子来说明所得结果的意义.

英文摘要：

Using the method of composite expansion and the theory of differential inequality, a class of singularly perturbed boundary value problems for fourth order equations are studied. The formal asymptotic solutions of the problems are constructed by the method of composite expansion. Then the existence of solutions for the original problems and the uniform validity of the formal asymptotic solutions are proved by the theory of differential inequality. At last, an example is given to illustrate the significance of the obtained result.