diff --git a/SPHINXsys/src/shared/particle_dynamics/solid_dynamics/solid_dynamics.cpp b/SPHINXsys/src/shared/particle_dynamics/solid_dynamics/solid_dynamics.cpp
index 0450ced2dc..0d831c9dfa 100644
--- a/SPHINXsys/src/shared/particle_dynamics/solid_dynamics/solid_dynamics.cpp
+++ b/SPHINXsys/src/shared/particle_dynamics/solid_dynamics/solid_dynamics.cpp
@@ -374,43 +374,51 @@ namespace SPH
 					pos_n_(particles_->pos_n_),
 					pos_0_(particles_->pos_0_),
 					vel_n_(particles_->vel_n_),
-					dvel_dt_prior_(particles_->dvel_dt_prior_),
-					mass_(particles_->mass_)
+					dvel_dt_prior_(particles_->dvel_dt_prior_)
 		{
-			stiffness_ = stiffness;
-			damping_ratio_ = damping_ratio;
+			// calculate total mass
+			total_mass_ = 0.0;
+			for (int i = 0; i < particles_->mass_.size(); i++)
+			{
+				total_mass_ += particles_->mass_[i];
+			}
+			// scale stiffness and damping by mass here, so it's not necessary in each iteration
+			stiffness_ = stiffness / total_mass_;
+			damping_coeff_ = stiffness * damping_ratio / total_mass_;
 		}
 		//=================================================================================================//
+		SpringDamperConstraintParticleWise::~SpringDamperConstraintParticleWise()
+		{}
+		//=================================================================================================//
 		void SpringDamperConstraintParticleWise::setupDynamics(Real dt)
 		{
 			particles_->total_ghost_particles_ = 0;
 		}
 		//=================================================================================================//
-		Vecd SpringDamperConstraintParticleWise::getAcceleration(Vecd& disp, Real mass)
-		{
+		Vecd SpringDamperConstraintParticleWise::getSpringForce(size_t index_i, Vecd& disp)
+		{	
 			Vecd spring_force(0);
 			for(int i = 0; i < disp.size(); i++)
 			{
-				spring_force[i] = -stiffness_[i] * disp[i] / mass;
-			}
+				spring_force[i] = -stiffness_[i] * disp[i];
+			}			
 			return spring_force;
 		}
 		//=================================================================================================//
-		Vecd SpringDamperConstraintParticleWise::getDampingForce(size_t index_i, Real mass)
+		Vecd SpringDamperConstraintParticleWise::getDampingForce(size_t index_i)
 		{
 			Vecd damping_force(0);
 			for(int i = 0; i < vel_n_[index_i].size(); i++)
 			{
-				damping_force[i] = -stiffness_[i] * damping_ratio_ * vel_n_[index_i][i] / mass;
+				damping_force[i] = -damping_coeff_[i] * vel_n_[index_i][i];
 			}
 			return damping_force;
 		}
 		//=================================================================================================//
 		void SpringDamperConstraintParticleWise::Update(size_t index_i, Real dt)
 		{	
-			Vecd disp_from_0 = pos_n_[index_i] - pos_0_[index_i];
-			dvel_dt_prior_[index_i] += getAcceleration(disp_from_0, mass_[index_i]);
-			dvel_dt_prior_[index_i] += getDampingForce(index_i, mass_[index_i]);
+			dvel_dt_prior_[index_i] += getSpringForce(index_i, pos_n_[index_i] - pos_0_[index_i]);
+			dvel_dt_prior_[index_i] += getDampingForce(index_i);
 		}
 		//=================================================================================================//
 		AccelerationForBodyPartInBoundingBox::
diff --git a/SPHINXsys/src/shared/particle_dynamics/solid_dynamics/solid_dynamics.h b/SPHINXsys/src/shared/particle_dynamics/solid_dynamics/solid_dynamics.h
index 6eb6cbc999..c3fe257cc5 100644
--- a/SPHINXsys/src/shared/particle_dynamics/solid_dynamics/solid_dynamics.h
+++ b/SPHINXsys/src/shared/particle_dynamics/solid_dynamics/solid_dynamics.h
@@ -296,23 +296,23 @@ namespace SPH
 		* @brief Exerts spring force and damping force in the form of acceleration to each particle.
 		* The spring force is calculated based on the difference from the particle's initial position.
 		* The damping force is calculated based on the particle's current velocity.
+		* Only for 3D applications
 		*/
 		class SpringDamperConstraintParticleWise 
 			: public ParticleDynamicsSimple, public SolidDataSimple
 		{
 		public:
-			SpringDamperConstraintParticleWise(SolidBody* body, Vecd stiffness, Real damping_ratio = 0.01);
-			virtual ~SpringDamperConstraintParticleWise() {};
+			SpringDamperConstraintParticleWise(SolidBody* body, Vecd stiffness, Real damping_ratio = 0.05);
+			~SpringDamperConstraintParticleWise();
 		protected:
-			StdLargeVec<Real>& mass_;
+			Real total_mass_;
 			StdLargeVec<Vecd>& pos_n_,& pos_0_,& vel_n_,& dvel_dt_prior_;
 			Vecd stiffness_;
-			// damping component parallel to the spring force component
-			// damping coefficient = stiffness_ * damping_ratio_
-			Real damping_ratio_;
+			Vecd damping_coeff_; // damping component parallel to the spring force component
+
 			virtual void setupDynamics(Real dt = 0.0) override;
-			virtual Vecd getAcceleration(Vecd& disp, Real mass);
-			virtual Vecd getDampingForce(size_t index_i, Real mass);
+			virtual Vecd getSpringForce(size_t index_i, Vecd& disp);
+			virtual Vecd getDampingForce(size_t index_i);
 			virtual void Update(size_t index_i, Real dt = 0.0) override;
 		};
 		/**
@@ -389,12 +389,6 @@ namespace SPH
 			Real ReduceFunction(size_t index_i, Real dt = 0.0) override;
 		};
 
-		/**
-		* @function getSmallestTimeStepAmongSolidBodies
-		* @brief computing smallest time step to use in a simulation
-		*/
-		Real getSmallestTimeStepAmongSolidBodies(SPHBodyVector solid_bodies);
-
 		/**
 		* @class DeformationGradientTensorBySummation
 		* @brief computing deformation gradient tensor by summation