Hi i have adlx001 500g sensor, and I want to measure the acceleration in x direction, how can I mount it to  my mechanical design cuase I design a container and put it in it then mount it on my mechanical design but it doesn't work very well

Based on your picture, you want side-to-side acceleration measurement? Or do you want up-and-down acceleration measurement? The mounting screw holes imply the later. 

In any case, to get good data over, maybe, 5g, you will have to put the chip in direct contact with the case. At 500g, case strain can give you significant errors too. I'd suggest you mount the device's lid to a short (0.1") post that is machined into the case, in the direction of sensitivity. That means notching the post so that the chip's (opposite pin 8) side is resting on the post, and the labeled area of the lid is cemented to the post. This will be difficult with the Eval Board, but not impossible.

Based on your picture, you want side-to-side acceleration measurement? Or do you want up-and-down acceleration measurement? The mounting screw holes imply the later. 

In any case, to get good data over, maybe, 5g, you will have to put the chip in direct contact with the case. At 500g, case strain can give you significant errors too. I'd suggest you mount the device's lid to a short (0.1") post that is machined into the case, in the direction of sensitivity. That means notching the post so that the chip's (opposite pin 8) side is resting on the post, and the labeled area of the lid is cemented to the post. This will be difficult with the Eval Board, but not impossible.