Question: what is the value of this maximum acceleration?
Answer: " In Simple Harmonic Motion, the maximum of acceleration magnitude occurs at x = +/-A (the extreme ends where force is maximum), and acceleration at the middle ( at x = 0 ) is zero. " a = (d2x /dt2) = -Aω2 cos ( ωt). We may disregard the ( - ) signs if only the magnitudes are to be calculated.