var formData = new FormData();
if(($("#rep-file")[0].files).length != 0){
$.each($("#rep-file")[0].files,function(i, file){
formData.append("file["+i+"]",file);
});
}
console.log(formData);
var data = {
pnd: $('#pnd-report').val(),
text: $('#report-body').html(),
formData: formData
};
<label>Файл:
<input type="file" id="rep-file" name="" multiple>
</label>