ACTA MECH SOLIDA SIN is a Latin term that translates to "solid mechanics without fail". Synonyms for this phrase encompass various terms that convey similar meanings. One alternative could be "impeccable solid mechanics", which emphasizes the flawless nature of the work. Another synonym could be "unfailing solid mechanics", highlighting the reliability and consistency in this field. Additionally, "faultless solid mechanics" can be used to describe work that is error-free and precise. Synonyms like "flawless solid mechanics" and "infallible solid mechanics" also capture the essence of perfection and accuracy. Overall, these synonyms depict the notion of impeccable and reliable workmanship in the realm of solid mechanics.