Zero or negative mass in element number怎么办

显示动态分析接触摩擦时，出现如下错误，一直无法解决，请大神帮助～～

***ERROR: Zero or negative mass in element number PART-SPECIMEN-1.1250

***ERROR: Excessive distortion of element number 1250 of instance

PART-SPECIMEN-1

***ERROR: There is only one excessively distorted element

The following checklist may be helpful in diagnosing the error:

1. Check for poor initial mesh definition.

2. Check the parameters used for ALE. Reducing the number of
increments between ALE or increasing the number of sweeps in each ALE
increment may yield a better mesh.

3. Check contact definitions for problems such as excessive initial
overclosure or unrealistic tied definition between contact pairs.
A vector plot of velocities or accelerations will usually help to
identify contact problems.

4. Check stiffness (elastic modulus) and mass (density) definitions for
consistent units and verify that the combination is reasonable.

5. Check the boundary conditions for an excessive loading rate. The

*DIAGNOSTICS, DEFORMATION SPEED=DETAIL option may be used to obtain

detailed diagnostics information.

6. Check the current status of the structure to see if it has
totally failed.

7. A dashpot or a very stiff spring may cause the analysis to go unstable.

The *DYNAMIC, DIRECT option may be used to control the time increment
directly.

***ERROR: The fatal error will generate a new field output in the last

increment. All variables applicable to the current procedure and

material type(s) will be written to the output database.

***ERROR: Excessive distortion of element number 978 of instance

PART-SPECIMEN-1